minerals Article Richard Pažout 1, *, Jiří Sejkora 2 and Vladimír Šrein 3

minerals Article Ag-Pb-Sb Sulfosalts and Se-rich Mineralization of Anthony of Padua Mine near Poličany Model Example of the Mineralization of Silver Lodes in the Historic Kutná Hora Ag-Pb Ore District, Czech Republic Richard Pažout 1, *, Jiří Sejkora 2 and Vladimír Šrein 3 1 Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic 2 Department of Mineralogy and Petrology, National Museum, Cirkusová 1740, 193 00 Prague 9 Horní Počernice, Czech Republic 3 Czech Geological Survey, Klárov 3, 118 21 Prague 1, Czech Republic * Correspondence: richard.pazout@vscht.cz; Tel.: +420-220444080 Received: 3 May 2019; Accepted: 6 July 2019; Published: 12 July 2019 Abstract: Significant selenium enrichment associated with selenides and previously unknown Ag-Pb-Sb, Ag-Sb and Pb-Sb sulfosalts has been discovered in hydrothermal ore veins in the Anthony of Padua mine near Poličany, Kutná Hora ore district, central Bohemia, Czech Republic. The ore mineralogy and crystal chemistry of more than twenty silver minerals are studied here. Selenium mineralization is evidenced by a) the occurrence of selenium minerals, and b) significantly increased selenium contents in sulfosalts. Identified selenium minerals include aguilarite and selenides naumannite and clausthalite. The previously unknown sulfosalts from Kutná Hora are identified: Ag-excess fizélyite, fizélyite, andorite IV, andorite VI, unnamed Ag-poor Ag-Pb-Sb sulfosalts, semseyite, stephanite, polybasite, unnamed Ag-Cu-S mineral phases and uytenbogaardtite. Among the newly identified sulfides is argyrodite; germanium is a new chemical element in geochemistry of Kutná Hora. Three types of ore were recognized in the vein assemblage: the Pb-rich black ore (i) in quartz; the Ag-rich red ore (ii) in kutnohorite-quartz gangue; and the Ag-rich ore (iii) in milky quartz without sulfides. The general succession scheme runs for the Pb-rich black ore (i) as follows: galena boulangerite ( jamesonite) owyheeite fizélyite Ag-exces fizélyite andorite IV andorite VI freieslebenite diaphorite miargyrite freibergite. For the Ag-rich red ore (ii) and ore (iii) the most prominent pattern is: galena diaphorite freibergite miargyrite pyragyrite stephanite polybasite acanthite. The parallel succession scheme progresses from Se-poor to Se-rich phases, i.e., galena members of galena clausthalite solid solution clausthalite; miargyrite Se-rich miargyrite; acanthite aguilarite naumannite. A likely source of selenium is in the serpentinized ultrabasic bodies, known in the area of silver lodes in the South of the ore district, which may enable to pre-concentrate selenium, released into hydrothermal fluids during tectonic events. The origin of the studied ore mineralization is primarily bound to the youngest stage of mineralization of the whole ore district, corresponding to the Ag-Sb sequence of the eb ore type of the Freiberg ore district in Saxony (Germany) and shows mineralogical and geochemical similarities to low-sulfidation epithermal-style Ag-Au mineralization. Keywords: Ag-Pb-Sb sulfosalts; selenium-rich mineralization; Kutná Hora; clausthalite; naumannite; andorite group; argyrodite; Ag-Sb(-Au) alloys; acanthite aguilarite; succession Minerals 2019, 9, 430; doi:10.3390/min9070430 www.mdpi.com/journal/minerals

Minerals 2019, 9, 430 2 of 47 1. Introduction Kutná Hora was one of the best-known mining centres in Europe in the Middle Ages. In the first stage of mining (in the 13th and 14th century), the ores of silver-rich lodes in the southern part of the Kutná Hora ore district (Figure 1a) were mined extensively. By means of the so-called fire-setting mining technique 500 m depth below the surface was reached as early as before the end of 14th century [1,2]. Before the end of the 15th century, mining activity moved from the silver-rich southern part of the Kutná Hora ore district (especially Oselské pásmo Lode) to the northern part of this district, which had silver-bearing sulfide pyrite-rich ores (especially Staročeské pásmo Lode at Kaňk, north of Kutná Hora) (Figure 1a). The ores of the northern lodes (ore zones) were poorer in silver (200 300 g/t silver), but the veins were more massive and ore-abundant. Continually increasing operating costs and the discovery of cheaper silver from American deposits caused a decline of mining in Kutná Hora at the turn of the 16th and 17th century [2]. The knowledge of mineralogy of ore veins in the southern silver-rich part of the Kutná Hora ore district has so far been incomplete. Mining in this historically important part of the ore district ended in the 16th century and later explorations were carried out only on a very limited scale [3 8]. Therefore, mineralogical research of this part of the ore district had to rely only on occasional finds of primary mineralization on medieval mine dumps, mostly localized in areas built up by medieval town [8], but still partly preserved south of the historic centre of the town. Known silver minerals from southern lodes of the ore district include acanthite [9,10], allargentum [9,11], diaphorite [12,13], freibergite [13], freieslebenite [14], miargyrite [13,15], owyheeite [16], proustite [13], pyragyrite [13], pyrostilpnite [17], stephanite [11], silver [9],Au-rich silver and Au-bearing dyscrasite [11].No selenium minerals have been known, no selenium contents above detection limit determined. In northern lodes, the following silver minerals not occurring in southern lodes were described: canfieldite [18], gustavite [19,20] and matildite [21]. The pyrite-rich assemblage has recently yielded a rich suite of Ag-Pb-Bi-Sb sulfosalts. Recently identified minerals from northern lodes include terrywallaceite, vikingite, treasurite, eskimoite, erzwiesite, izoklakeite, aramayoite [22,23] and new mineral staročeskéite [24]. Minerals 2019, 9, x FOR PEER REVIEW 3 of 45 Figure 1. (a) Map of the Kutná ore district with major ore lodes, adapted from Malec and Pauliš Figure 1. (a) Map of the Kutná Hora ore district with major ore lodes, adapted from Malec and [25]. Each lode ( pásmo in Czech, Zug in German) consists of several veins. (b) map of Anthony Pauliš [25]. Each lode ( pásmo in Czech, Zug in German) consists of several veins. (b) map of of Padua mine, Kutná Hora, adapted from Koutek and Kutina [26]. The blue-marked sections are Anthonyore-mineralized. of Padua mine, Kutná Hora, adapted from Koutek and Kutina [26]. The blue-marked sections are ore-mineralized. 2. Geological Setting 2.1. KutnáHora Ore District The Kutná Hora Ag-Pb-Zn ore district (60 km east of Prague, Central Bohemia, Czech Republic) represents a hydrothermal vein type mineralization of Variscan age [26]. The ore district covers the area of 10 5 km in N-S direction. Ore veins are clustered in so-called ore zones or lodes ( pásmo in

Minerals 2019, 9, 430 3 of 47 The small Anthony of Padua Mine, located near the village of Poličany in the southern part of the Kutná Hora ore district, has been preserved to this day owing to the renewed exploration mining during the World War II. Thus, the mine represents a unique opportunity to study in detail the mineralogy of Ag-rich ores both in dump material and also in situ, sampled in the ore veins uncovered inside the mine. Therefore, it is a very appropriate model example, providing a large abundance and variety of new information on the mineralogy of the southern part of the Kutná Hora ore district, including the newly discovered, previously unknown selenium mineralizations from Kutná Hora. 2. Geological Setting 2.1. Kutná Hora Ore District The Kutná Hora Ag-Pb-Zn ore district (60 km east of Prague, Central Bohemia, Czech Republic) represents a hydrothermal vein type mineralization of Variscan age [26]. The ore district covers the area of 10 5 km in N-S direction. Ore veins are clustered in so-called ore zones or lodes ( pásmo in Czech), each 1 to 3 km in length and 100 500 m in width (Figure 1a). A detailed description of the geological and mineralogical situation of the Kutná Hora ore district is given in [25 27]. The genetical, geological, mineralogical and chemical similarities of the ore districts of Kutná Hora and Freiberg (Germany) have been studied and pointed out by several authors, e.g. [28,29]. In general, two mineral assemblages are present in the ore district: one silver-rich, developed in gneisses of the Varied unit of the Kutná Hora Crystalline Complex in the south, and the other pyrite-rich in gneisses and migmatites of the Malín unit in the north [25,26]. The silver-rich assemblage consists mainly of miargyrite, pyrargyrite, freibergite, freieslebenite, diaphorite, allargentum, native silver, galena, pyrite, sphalerite, berthierite and Pb-Sb(-Ag) sulfosalts (boulangerite, jamesonite, owyheeite) in quartz kutnohorite gangue [25,27]. The pyrite-rich assemblage comprises pyrite, arsenopyrite, sphalerite, Ag-bearing galena, pyrrhotite, marcasite, chalcopyrite, stannite, freibergite and Pb-Sb-Bi-Ag) sulfosalts in quartz gangue without kutnohorite. The presence of Bi and Sn (each from a different mineralization sequence) is typical, while it is completely absent in the former, silver-rich assemblage. The pyrite-rich assemblage yields a rich suite of Ag-Pb-Bi-Sb sulfosalts, recently studied by Pažout [22,23]. 2.2. Anthony of Padua Mine Near Poličany Anthony of Padua mine is situated south of Kutná Hora near the village of Poličany in the valley of the Vrchlice stream, about 200 m SSW of Kruchta Mine, which is the southernmost historically documented mine of the Oselské pásmo Lode, the largest silver lode of the medieval Kutná Hora ore disctrict. Geologically and mineralogically, the mine belongs to the Oselské pásmo Lode. The adit of the Anthony of Padua mine (situated at GPS: 49 55.77858 N, 15 15.29307 E) accesses ore veins that belong to the southern silver-rich Oselské pásmo Lode (Figure 1a). The first mine workings in this area began probably already around 1300; written references about mining activity come from 1752 1755 [7,30,31] and 1769 1770 [32]. The last exploration works in the adit were undertaken in 1943 1945 [32]; at present, this abandoned mine is still partially accessible. Ore veins of the Anthony of Padua Mine are developed in gneisses of the Varied unit of the Kutná Hora Crystalline Complex, namely in proterozoic medium to strongly migmatized double-mica paragneisses with transition to migmatites with interbeds of muscovite-biotite othogneisss; the composition of wall rock has no or little influence on hydrothermal mineralization [32]. These rocks are classed as belonging to the Šternberk-Čáslav Group established by [26] and [33]. In the central part of the Kutná Hora ore district, the rocks of the Crystalline unit are covered by Cretaceous and later Quaternary sediments, while in the valley of the stream of Vrchlice near Poličany Cretaceous sediments are missing and Quaternary sediments are denudated. Anthony of Padua mine accesses five ore veins with strings in a zone or area 30 40 m wide (Figure 1b), with a typical thickness of 20 to 50 cm (occasionally bulging to 1 m) and N S to NNE SSW

Minerals 2019, 9, 430 4 of 47 direction. Therefore, some veins intersect, or are considered to be strings. Some dip 60 to 85 to the E, other to the W [32]. Vein gangue consists of quartz and kutnohorite with disseminated or massive sulfides. The mineralogy of ores found in Anthony of Padua mine was systematically studied for the first time by Koutek and Kutina [32], which was followed by another paper by Kutina [34], presenting the results of semi-quantitative chemical analyses. The results of shorter papers are summarized in [35] and newly in concise articles of [25,27,36]. Known silver minerals from the Anthony of Padua mine include: miargyrite, pyrargyrite, freibergite, diaphorite, freieslebenite and silver. Until now, only contents of Se up to 0.14 were found [35] in galena from Anthony of Padua mine. 3. Sampling and Analytical Methods The studiedore samples were collected in situin the adit of Anthony of Padua mine (Figure 1b), from spots described in Section 4.1. Samples for microscopy and following laboratory study were prepared as polished sections 2.54 cm in diameter, mounted in resin and polished with diamond suspensions. The ore minerals and textures were studied in reflected light using a Nikon Eclipse ME600 polarizing microscope in the National Museum, Prague. Seventy polished sections, prepared from a representative number of ore specimens collected during field work in 1999 2015, were investigated microscopically and subsequently analysed on two different electron microprobes (3000 point analyses altogether). Quantitative chemical analysis was performed with Cameca SX electron microprobe (EPMA, National Museum, Prague), WDS analysis, operated at 25 kv, 20 na, and a beam diameter of 2 µm. The following standards and X-ray lines were used: Ag (AgLα), CdTe (CdLα), CuFeS 2 (CuKα), FeS 2 (FeKα, SKα), NiAs (AsLβ), PbCl 2 (ClKα), PbS (PbMα), PbSe (SeLβ), Sb 2 S 3 (SbLα) a ZnS (ZnKα). Raw intensities were converted to the concentrations of elements using automatic PAP matrix-correction software. The second portion of polished sections (incl. Au-rich silver) was analysed with the electron probe microanalyser JEOL JXA-8530F at Institute of Petrology and Structural Geology, Faculty of Natural Sciences, Charles University, Prague. Accelerating voltage was 20 kv, beam current 20 na and electron-beam diameter 1 µm. The following standards and X-ray lines were used: Au (AuLα), Ge (GeLα), cuprite (CuKα), cinnabar (HgLα), Bi 2 Se 3 (SeLα), Ag (AgLα), Sb 2 Te 3 (TeLα), stibnite (SbLα) and marcasite (SKα). Measured data were corrected using ZAF method. Peak-counting times were 20 30 s and one-half of the peak time was used for each background. The contents of the above-listed elements, which are not included in the tables, were analysed quantitatively, but their contents were below the detection limit (ca. 0.01 0.04 for individual elements). 4. Mineralogy and Mineral Chemistry Results 4.1. Characterization of Ore Mineralization of Anthony of Padua Mine The majority of the studied material comes from Vein B (Figure 1b), with a thickness of 20 60 cm, NNE SSW direction and dipping 65 to the East. Two basic kinds of ore mineralization were found in this vein: (i) Pb-rich (so called black ore ) and (ii) silver-rich (so called red ore ), differing in associated minerals, prevailing and present elements and gangue minerals. Black ore (i) is formed by massive or disseminated grain aggregates (up to the size of 15 cm) consisting of galena, miargyrite, massive Pb-Sb sulfosalts (boulangerite, jamesonite) and pyrite in quartz gangue and fewer carbonates (kutnohorite). Accessory minerals include freibergite, sphalerite, Ag-Pb-Sb sulfosals (diaphorite, freieslebenite, minerals of the andorite series, owyheeite). Selenium is present in members of galena clausthalite solid solution.

Minerals 2019, 9, 430 5 of 47 On the other hand, the Ag-rich red ore (named after its marked colour) ore (ii) consists of grains of miargyrite up to 5 centimetres across, associated with pyrargyrite, freibergite, with crystals up to 5 mm in occasional cavities, small metallic outgrowths of native silver up to 3 mm, coarse-grained sphalerite and massive pyrite in kutnohorite and quartz. Ag-Pb-Sb sulfosalts are rare or non-present (no andorite group minerals). Accessory minerals include aguilarite, selenides naumannite and clausthalite, high-grade silver minerals (stephanite, acanthite), germanium is present in argyrodite and Au occurs as Au-rich silver (electrum) and Au-rich dyscrasite. Another portion of the studied material, representing ore (iii), comes from the intersection of the vein I and the vein A (Figure 1b); the main vein I, with a thickness of 20 80 cm, N S direction and dipping 65 80 to the E, cuts and shifts by several decimetres a diagonal vein A with the thickness of 20 40 cm, NE SW direction and with dips of 35 65 to the SE. The prevailing mineral is miargyrite in milky white quartz, the sparse associated base sulfide (if it occurs) is pyrite. Miargyrite forms massive grains, bands and veinlets up to several cm in size and well-developed crystals in quartz cavities, usually several mm in size. The maximum size of individual crystal exceeds 1 cm. Often, thin red fillings of miargyrite in fractures and fissures in quartz occur. Miargyrite is accompanied by less frequent pyrargyrite, freibergite, pyrostilpnite, diaforite and freieslebenite. 4.2. Pb-Sb-Ag Sulfosalts 4.2.1. Diaphorite Ag 3 Pb 2 Sb 3 S 8 Diaphorite is a frequently occurring mineral in studied material (200 point analyses). It was found as anhedral grains up to 150 200 µm in size, most often associated with galena, freieslebenite, boulangerite, freibergite, jamesonite and andorite group minerals in black ore (i) (Figure 2a e). In the general succession that follows the trend from Pb-rich phases to Ag-rich phases, it is usually a later mineral than freieslebenite and is replaced by freibergite or miargyrite. Macroscopically, visible to naked eye, diaphorite forms lead to steel grey striated crystals up to 3 mm in quartz cavities (occasionally tarnishing black or bronze) and grain aggregates several mm in size in quartz gangue of ore (iii) (Figure 2f) or kutnohorite quartz gangue of red ore (ii). The chemical composition of diaphorite from the Anthony of Padua mine (Table 1) shows a considerable variation in Ag/Pb ratio in the range 1.47 1.80. Mozgova et al. [37] describedthe compositional variation in diaphorite on the basis of microanalytical and crystal structure data from various diaphorite occurrences. They speculated on a continuous solid solution series between diaphorite and a phase with the formula Ag 2 PbSb 2 S 5 (old unvalid name brongniardite ) and considered that this phase with Ag/Pb ratios between 1.75 and 2.00 may be an Ag-rich diaphorite. This argument would be supported by the study of diaphorite from Herja (Ag/Pb 1.53 1.69), Rumania [38] or Apuan Alps (Ag/Pb 1.67), Italy [39]. On the other hand, the published data for diaphorite from Kutná Hora [12,35] or Příbram [40] show compositions close to ideal stoichiometry (Ag/Pb 1.44 1.54). The detected range of SSe 1 substitution is limited to 0.29 apfu Se (1.71 ). The maximum contents of Se were found in samples with Ag/Pb ratio about 1.6. Traces of As were also determined. 4.2.2. Freieslebenite AgPbSbS 3 Freieslebenite is fairly common in the studied assemblage (200 point analyses), it occurs as anhedral grains up to 60 100 µm in size in black ore (i) in association with boulangerite, owyheeite, galena, diaphorite and miargyrite. Freislebenite is a later mineral than galena and it is replaced by later diaphorite, miargyrite and minerals of the tetrahedrite groups (Figure 2a c). Macroscopically, freieslebenite was found as striated steel grey or black metallic crystals up to 2 mm in quartz cavities or grain aggregates in ore (iii).

Minerals 2019, 9, 430 6 of 47 Minerals 2019, 9, x FOR PEER REVIEW 6 of 45 (a) (b) Dia Bou Frs Prg Ow Bou Dia Frs Frs Dia 100 m 200 m (c) Mia (d) Frs Mia Dia Frg Jms Mia Ow Mia Dia 200 m Mia 100 m (e) (f) Prg Ste Mia Dia Frg Mia 100 m Frs Ste Dia Mia 1000 m Mia Dia Frg Figure 2. (a) Black ore (i) association (from the earliest to the latest mineral): galena (), boulangerite (Bou), Figure freieslebenite 2. (a) Black (Frs), ore (i) diaphorite association (Dia), (from pyrargyrite the earliest (Prg); to (b) the example latest of mineral): black ore galena (i) association (), with boulangerite the general (Bou), succession freieslebenite from the (Frs), Pb-richest diaphorite to Pb-poorer (Dia), pyrargyrite phases: (Prg); galena (b) () example boulangerite of black (Bou) ore freieslebenite (i) association (Frs) with the owyheeite general (Ow) succession fizélyite from (Fiz) the Pb-richest Ag-excessto fizélyite Pb-poorer () phases: diaphorite galena (Dia); () (c) a later-stage boulangerite replacement (Bou) freieslebenite of galena of(frs) black ore owyheeite (i) by Ag-richer (Ow) fizélyite minerals (Fiz) following Ag-excess the succession: fizélyite () galena (white) diaphorite freieslebenite (Dia); (c) (Frs) a later-stage diaphorite replacement (Dia) freibergite of galena (Frg) of black miargyrite ore (i) by (Mia) Ag-richer jamesonite minerals (Jms); (d) following needlesthe of owyheeite succession: (Ow) galena replaced (white) by freieslebenite diaphorite (Dia) (Frs) and diaphorite Ag-excess(Dia) fizélyite freibergite (); all(frg) minerals are miargyrite subsequently (Mia) being jamesonite replaced (Jms); by(d) miargyrite needles of (Mia); owyheeite (e) (Ow) five Ag-minerals replaced by diaphorite in one image: (Dia) and galena () Ag-excess replaced fizélyite by freislebenite (); all minerals (Frs), diaphorite are subsequently (Dia) and being Ag-excess replaced by fizélyite miargyrite (), (Mia); all replaced (e) five by miargyrite Ag-minerals (Mia). in one Stephanite image: galena (Ste) () is the replaced latest mineral. by freislebenite (f) typical (Frs), example diaphorite of ore (Dia) (iii) and with Ag-excess prevailing fizélyite (), all replaced by miargyrite (Mia). Stephanite (Ste) is the latest mineral. (f) typical miargyrite (Mia) in quartz gangue, remnants of galena (white) are replaced by diaphorite (Dia) which example of ore (iii) with prevailing miargyrite (Mia) in quartz gangue, remnants of galena (white) are is subsequently replaced by miargyrite, locally with pyraragyrite inclusions (Prg); freibergite (Frg) is also present. All back-scattered electron images.

Minerals 2019, 9, 430 7 of 47 Table 1. EPMA data for diaphorite. apfu Σ16 Atoms Ag Pb Sb As Se S Total Ag Pb Sb As Se S 477 24.21 29.15 26.95 0.05 0.27 18.86 99.48 3.04 1.91 3.00 0.01 0.05 7.97 1107 23.63 28.95 27.22 0.09 0.42 18.73 99.03 2.98 1.90 3.05 0.02 0.07 7.96 1106 23.96 28.74 27.60 0.03 0.45 18.55 99.33 3.03 1.89 3.09 0.01 0.08 7.89 1733 23.84 28.99 27.36 0.18 0.46 18.49 99.32 3.02 1.91 3.07 0.03 0.08 7.87 1850 23.43 29.41 27.34 0.15 0.53 18.75 99.60 2.95 1.93 3.05 0.03 0.09 7.93 727 24.01 28.87 27.02 0.10 0.56 18.82 99.38 3.01 1.89 3.01 0.02 0.10 7.95 1660 24.23 29.38 27.55 0.17 0.65 18.59 100.56 3.03 1.91 3.06 0.03 0.11 7.83 1223 24.31 28.52 27.23 0.09 0.99 18.47 99.61 3.05 1.86 3.03 0.02 0.17 7.80 2116 23.53 29.30 27.21 0.00 1.08 18.37 99.49 2.98 1.93 3.05 0.00 0.19 7.83 1886 24.24 29.53 27.49 0.00 1.29 18.71 101.25 3.01 1.91 3.02 0.01 0.22 7.82 799 24.08 29.20 27.61 0.06 1.64 18.37 100.97 3.01 1.90 3.06 0.01 0.28 7.72 800 24.42 29.31 27.83 0.05 1.71 18.44 101.76 3.03 1.89 3.06 0.01 0.29 7.69 are ordered according to increasing Se content. Chemical composition of freieslebenite is relatively uniform and close to ideal formula (Table 2); traces of As were identified. The anion part features contents of Se (up to 0.05 apfu, i.e., 0.71 ). The SeS 1 substitution in freieslebenite is the least pronounced of all Ag-Pb-Sb sulfosalts, the maximum determined contents of Se are only 0.71 compared to 1.71 in diaphorite and 4.69 in Ag-excess fizélyite. The empirical formula for studied freieslebenite on the basis of 6 apfu (mean of 138 analyses) can be expressed as Ag 0.99 (Pb 0.98 Fe 0.01 ) Σ0.99 Sb 1.02 (S 2.97 Se 0.02 ) Σ2.99. Table 2. EPMA data for freieslebenite. apfu Σ6 Atoms Ag Pb Sb As Se S Total Ag Pb Sb As Se S 569 20.50 37.96 23.61 0.08 0.28 18.39 100.82 0.99 0.96 1.01 0.01 0.02 3.00 1737 20.17 38.44 23.19 0.13 0.38 17.99 100.30 0.99 0.98 1.01 0.01 0.03 2.97 1861 20.14 38.57 23.33 0.15 0.40 18.21 100.80 0.98 0.98 1.01 0.01 0.03 2.99 1205 20.18 38.14 23.31 0.09 0.41 17.91 100.03 0.99 0.98 1.02 0.01 0.03 2.97 610 20.59 37.90 23.27 0.06 0.42 17.90 100.14 1.01 0.97 1.01 0.00 0.03 2.96 429 20.37 38.21 23.06 0.12 0.44 18.03 100.24 1.00 0.97 1.00 0.01 0.03 2.97 713 20.37 38.41 23.14 0.06 0.45 17.98 100.41 1.00 0.98 1.00 0.00 0.03 2.96 430 20.50 37.94 22.89 0.16 0.55 17.89 99.93 1.01 0.97 1.00 0.01 0.04 2.96 2149 20.13 37.90 23.15 0.00 0.66 17.83 99.67 0.99 0.97 1.01 0.00 0.04 2.96 2152 20.33 37.75 22.89 0.00 0.71 17.49 99.17 1.01 0.98 1.01 0.00 0.05 2.93 are ordered according to increasing Se content. 4.2.3. Ag-excess fizélyite Ag 6 Pb 14 Sb 21 S 48 Ag-excess fizélyite (AEF) is by far the most abundant of all andorite minerals (ca. 770 analytical points compared to ca. 100 points of all other andorite minerals put together Figure 3). It is fairly frequent among microprobe analyses in polished sections. It occurs as anhedral grains, occasionally as semi-euhedral or column-like aggregates, usually up to 100 µm, in exceptional casesup to 1500 µm (Figure 4), in black ore (i), most frequently associated with galena, boulangerite, jamesonite, owyheeite, other andorite group minerals and miargyrite (Figure 2b,d,e, Figure 5a d). AEF usually replaces andorite IV, itself being replaced by freibergite and miargyrite.

frequent among microprobe analyses in polished sections. It occurs as anhedral grains, occasionally as semi-euhedral or column-like aggregates, usually up to 100 μm, in exceptional casesup to 1500 μm (Figure 4), in black ore (i), most frequently associated with galena, boulangerite, jamesonite, owyheeite, other andorite group minerals and miargyrite (Figures 2b,d,e, 5a d). AEF usually replaces andorite IV, itself being replaced by freibergite and miargyrite. Minerals 2019, 9, 430 8 of 47 Minerals 2019, 9, x FOR PEER REVIEW 9 of 45 Ag-excess fizélyite was described for the first time on the basis of chemical analyses as minéral F from Les Farges (France) by Moëlo et al. [41] and later from the Lill mine in Příbram (Czech Republic) by Plášil et al. [42]. Structurally, it was defined by Yang et al. [43] in samples from Van Silver mine, Canada. It significantly differs from fizélyite in its higher Ag content. The excess silver is situated at the Ag2 site in the structure [43], which remains unoccupied in normal fizélyite. Higher Ag contents result in a shift of calculated Nchem (the width of the blocks of octahedra separated by Pb atoms in trigonal prismatic coordination) to higher values above 4. The mineral from Van Silver mine [43] shows calculated values of Nchem in the range of 4.31 4.59, mean 4.42. AEF from the Anthony of Padua Mine (Table 3) shows a wider range of Nchem values of 4.27 4.91, mean 4.54 (Figure 4). The determined range of the andorite substitution (Ag + Sb = 2Pb) varies between 57.6 and 67.4% (mean 63.7). Apart from sulphur, the anion contains significant selenium content up to 4.48 apfu (4.69 ) (Figure 6), which is considerably higher than in all other andorite group minerals. The empirical formula for studied Ag-excess fizélyite on the basis of 88 apfu (mean of 767 analyses) can be expressed as (Ag5.91Cu0.03)Σ5.94(Pb13.91Fe0.15Mn0.06)Σ14.12(Sb20.57As0.07)Σ20.64(S47.68Se0.53)Σ48.21. Figure Figure 3. Graph 3. Graph N chem Nchem value vs%and substitution (L%) for andorite group minerals. Frs 500 m Figure Figure 4. An 4. An exceptionally large large grain of Se-rich Ag-excess fizélyite (), (), 1500 1500 μm µmacross, across, with with a a variable variable Se Se content content (0.31 1.23 (0.31 1.23 of of Se). Se). Ag-excess fizélyite fizélyite replaces replaces earliest earliest galena galena () () and and is is replaced by freieslebenite (Frs). replaced by freieslebenite (Frs).

Minerals 2019, 9, 430 9 of 47 Minerals 2019, 9, x FOR PEER REVIEW 10 of 45 (a) (b) Ad4 Ad4 200 m 100 m Ad4 Ad6 Frs (c) (d) Ow Ow Bou Ow Dia 200 m Ow 100 m Figure 5. (a) Andorite IV (Ad4) replaces Ag-excess fizélyite (); (b) grain of Ag-excess fizélyite () in Figure kutnohorite 5. (a) Andorite of blackiv ore (Ad4) (i) isreplaces replacedag-excess by andorite fizélyite IV (Ad4), (); which (b) grain is subsequently of Ag-excess replaced fizélyite by andorite () in kutnohorite VI (Ad6; ragged of black edges). ore (i) Ag-excess is replaced fizélyite by andorite is further IV (Ad4), replaced which by freieslebenite is subsequently (Frs; replaced right side of by the andorite grain); VI (c) (Ad6; galena ragged () edges). replaced Ag-excess by boulangerite fizélyite is (Bou) further andreplaced owyheeite by freieslebenite (Ow), both minerals (Frs; subsequently right side of the replaced grain); by (c) Ag-excess galena () fizélyite replaced ();(d) by boulangerite earliest galena (Bou) () and replaced owyheeite by owyheeite (Ow), both (Ow), Ag-excess minerals subsequently fizélyite () replaced and diaphorite by Ag-excess (Dia). All fizélyite back-scattered ();(d) earliest electron galena images. () replaced by owyheeite (Ow), Ag-excess fizélyite () and diaphorite (Dia). All back-scattered electron images. Ag-excess fizélyite was described for the first time on the basis of chemical analyses as minéral F Table 3. EPMA data for of Ag-excess fizélyite. from Les Farges (France) by Moëlo et al. [41] and later from the Lill mine in Příbram (Czech Republic) by apfu Ʃ88 Atoms Plášil et al. [42]. Structurally, it was defined by Yang et al. [43] in samples from Van Silver mine, Ag Pb Fe Cd Mn Sb Se S Total Ag Pb Fe Cd Mn Sb Se S N L% Canada. It significantly differs from fizélyite in its higher Ag content. The excess silver is situated 1868 7.86 37.19 0.49 0.00 0.12 33.51 0.06 20.70 100.12 5.39 13.29 0.65 0.00 0.16 20.38 0.05 47.80 4.29 62.36 at 1496 the Ag2 8.63 site 37.28 in the 0.10 structure 0.00 0.05 33.12 [43], 0.28 which 20.22 remains 99.86 6.01 unoccupied 13.51 0.13 0.00 in normal 0.07 20.43 fizélyite. 0.27 47.35 4.50 Higher 65.88 Ag 767 8.37 37.46 0.14 0.21 0.05 32.74 0.35 20.24 99.67 5.82 13.56 0.19 0.14 0.06 20.16 0.33 47.34 4.58 62.68 contents result in a shift of calculated N 1392 7.84 38.31 0.13 0.00 0.20 32.23 0.46 chem (the width of the blocks of octahedra separated by Pb 20.07 99.36 5.50 13.99 0.17 0.27 20.03 0.44 47.35 4.54 60.74 atoms 1955 in8.20 trigonal 37.20 0.11 prismatic 0.00 0.05 coordination) 33.77 0.70 20.24 to 100.33 higher5.68 values 13.42 above 0.15 0.004. 0.07 The20.73 mineral 0.66 47.18 from4.31 Van65.29 Silver 594 8.51 35.97 0.46 0.02 0.14 34.03 0.75 20.13 100.10 5.86 12.89 0.62 0.01 0.19 20.76 0.71 46.60 4.45 64.55 mine [43] shows calculated values of N 647 8.79 38.52 0.08 0.00 0.04 32.45 0.85 chem in the range of 4.31 4.59, mean 4.42. AEF from the Anthony 20.07 100.86 6.10 13.93 0.11 0.00 0.05 19.97 0.80 46.88 4.83 63.19 of 1920 Padua7.99 Mine 37.65 (Table 0.71 0.00 3) shows 0.03 32.84 a wider 0.96 19.79 range 100.03 of N5.57 chem 13.67 values 0.95 of 0.004.27 4.91, 0.05 20.29 mean 0.91 46.43 4.544.50 (Figure 60.53 4). 781 8.52 36.31 0.21 0.00 0.06 33.38 1.26 20.01 99.84 5.91 13.11 0.29 0.00 0.09 20.52 1.19 46.71 4.49 65.84 The determined range of the andorite substitution (Ag + Sb = 2Pb) varies between 57.6 and 67.4% (mean 641 8.29 37.58 0.11 0.00 0.04 32.86 1.66 19.65 100.19 5.80 13.70 0.14 0.00 0.06 20.39 1.59 46.29 4.50 63.74 63.7). 783 Apart 8.86 from 36.07 sulphur, 0.19 0.00 the 0.05 anion 33.39 1.87 contains 19.70 significant 100.33 6.14 13.02 selenium 0.25 0.00 content 0.07 up 20.51 to1.77 4.4845.95 apfu 4.63 (4.6967.05 ) 784 8.76 36.52 0.11 0.00 0.05 33.03 2.05 19.57 100.31 6.09 13.23 0.15 0.00 0.07 20.37 1.95 45.82 4.70 66.34 (Figure 6), which is considerably higher than in all other andorite group minerals. The empirical 1148 8.71 36.68 0.05 0.00 0.02 31.99 2.86 19.14 99.47 6.14 13.47 0.06 0.00 0.03 19.99 2.75 45.42 4.73 64.83 formula 1144 for 8.72 studied 36.93 0.02 Ag-excess 0.00 0.00 fizélyite 32.71 3.50 on18.84 the basis 100.75 of 6.13 88 13.50 apfu (mean 0.03 0.00 of 0.00 767 analyses) 20.35 3.36 can 44.51 be4.64 expressed 65.70 1145 8.82 36.93 0.03 0.00 0.00 32.61 3.49 18.63 100.53 6.23 13.58 0.03 0.00 0.00 20.41 3.37 44.27 4.70 65.69 as (Ag 1143 5.91 Cu 9.07 0.03 ) 37.30 Σ5.94 (Pb 0.02 0.00 13.91 Fe 0.01 0.15 Mn 33.11 4.69 0.06 ) Σ14.12 (Sb 18.63 102.91 20.57 As 6.28 0.07 ) 13.43 Σ20.64 (S 0.03 0.00 47.68 Se 0.01 0.53 ) 20.29 Σ48.21. 4.43 43.34 4.73 65.98 are ordered according to increasing Se content.

Minerals 2019, 9, 430 10 of 47 4.2.4. Fizélyite Ag 5 Pb 14 Sb 21 S 48 Fizélyite occurs only rarely in polished section (determined in only seven samples) as euhedral grains of tabular shape with hypoparallel intergrowth. It occurs as inclusions of up to 50 µm in jamesonite enclosed in boulangerite which replaces galena. It also occurs as individual grains in quartz up to 100 µm associated with jamesonite and miargyrite. It is also associated with owyheeite, boulangerite, other andorite minerals and diaphorite (Figure 2a). It is found only in black ore (i), as with all andorite group minerals. The classification of fizélyite and Ag-excess fizélyite comes from the following assumptions. The formula of fizélyite is Ag 5 Pb 14 Sb 21 S 48, which gives N = 4.00 and L% = 62.49. The formula of Ag-excess fizélyite is Ag 6 Pb 14 Sb 21 S 48, which corresponds to N = 4.46 and L% = 64.85. Considering that AEF defines one more Ag atom compared to fizélyite [43], the borderline between fizélyite and Ag-excess fizélyite must be guided by the content of 0.5 Ag atom more against fizélyite, i.e., by the formula Ag 5.5 Pb 14 Sb 21 S 48, which yields the values of N = 4.22 and L% = 63.76. Chemical composition of fizélyite and corresponding chemical formulae are given in Table 4. In comparison with Ag-excess fizélyite (Figure 3), the determined range of N chem values is centred around an ideal N value equal to 4 and ranges from 3.90 to 4.19 (mean 4.09). Determined values of the Ag + Sb = 2Pb substitution between 57.7 and 62.2% are slightly lower than 62.5 published for ideal fizélyite [41,43]. Found contents of Se do not exceed 1.17 apfu (1.20 ) (Figure 6) and are significantly lower than those found in Ag-excess fizélyite. Another difference against AEF is the presence of minor elements, namely iron. All fizélyite analyses show increased Fe between Minerals 2019, 0.38 9, x and FOR 0.94 PEER, REVIEW mean 0.59, while the same value for AEF is 0.20. The empirical 11 of 45 formula for studied fizélyite on the basis of 88 apfu (mean of 9 analyses) can be expressed as (Ag 4.83 Cu 0.02 ) Σ4.85 (Pb 13.58 Fe 0.83 Mn 0.06 Cd 0.03 ) Σ14.50 (Sb 20.61 As 0.04 ) Σ20.65 (S 47.53 Se 0.40 ) Σ47.93. Figure 6. 6. Graph Se/(S + Se) vs Ag (at.%) for andorite group minerals. 4.2.4. Fizélyite Ag5Pb14Sb21S48 Fizélyite occurs only rarely in polished section (determined in only seven samples) as euhedral grains of tabular shape with hypoparallel intergrowth. It occurs as inclusions of up to 50 μm in jamesonite enclosed in boulangerite which replaces galena. It also occurs as individual grains in quartz up to 100 μm associated with jamesonite and miargyrite. It is also associated with owyheeite, boulangerite, other andorite minerals and diaphorite (Figure 2a). It is found only in black ore (i), as with all andorite group minerals. The classification of fizélyite and Ag-excess fizélyite comes from the following assumptions. The formula of fizélyite is Ag5Pb14Sb21S48, which gives N = 4.00 and L% = 62.49. The formula of

Minerals 2019, 9, 430 11 of 47 Table 3. EPMA data for of Ag-excess fizélyite. apfu Σ88 Atoms Ag Pb Fe Cd Mn Sb Se S Total Ag Pb Fe Cd Mn Sb Se S N L% 1868 7.86 37.19 0.49 0.00 0.12 33.51 0.06 20.70 100.12 5.39 13.29 0.65 0.00 0.16 20.38 0.05 47.80 4.29 62.36 1496 8.63 37.28 0.10 0.00 0.05 33.12 0.28 20.22 99.86 6.01 13.51 0.13 0.00 0.07 20.43 0.27 47.35 4.50 65.88 767 8.37 37.46 0.14 0.21 0.05 32.74 0.35 20.24 99.67 5.82 13.56 0.19 0.14 0.06 20.16 0.33 47.34 4.58 62.68 1392 7.84 38.31 0.13 0.00 0.20 32.23 0.46 20.07 99.36 5.50 13.99 0.17 0.00 0.27 20.03 0.44 47.35 4.54 60.74 1955 8.20 37.20 0.11 0.00 0.05 33.77 0.70 20.24 100.33 5.68 13.42 0.15 0.00 0.07 20.73 0.66 47.18 4.31 65.29 594 8.51 35.97 0.46 0.02 0.14 34.03 0.75 20.13 100.10 5.86 12.89 0.62 0.01 0.19 20.76 0.71 46.60 4.45 64.55 647 8.79 38.52 0.08 0.00 0.04 32.45 0.85 20.07 100.86 6.10 13.93 0.11 0.00 0.05 19.97 0.80 46.88 4.83 63.19 1920 7.99 37.65 0.71 0.00 0.03 32.84 0.96 19.79 100.03 5.57 13.67 0.95 0.00 0.05 20.29 0.91 46.43 4.50 60.53 781 8.52 36.31 0.21 0.00 0.06 33.38 1.26 20.01 99.84 5.91 13.11 0.29 0.00 0.09 20.52 1.19 46.71 4.49 65.84 641 8.29 37.58 0.11 0.00 0.04 32.86 1.66 19.65 100.19 5.80 13.70 0.14 0.00 0.06 20.39 1.59 46.29 4.50 63.74 783 8.86 36.07 0.19 0.00 0.05 33.39 1.87 19.70 100.33 6.14 13.02 0.25 0.00 0.07 20.51 1.77 45.95 4.63 67.05 784 8.76 36.52 0.11 0.00 0.05 33.03 2.05 19.57 100.31 6.09 13.23 0.15 0.00 0.07 20.37 1.95 45.82 4.70 66.34 1148 8.71 36.68 0.05 0.00 0.02 31.99 2.86 19.14 99.47 6.14 13.47 0.06 0.00 0.03 19.99 2.75 45.42 4.73 64.83 1144 8.72 36.93 0.02 0.00 0.00 32.71 3.50 18.84 100.75 6.13 13.50 0.03 0.00 0.00 20.35 3.36 44.51 4.64 65.70 1145 8.82 36.93 0.03 0.00 0.00 32.61 3.49 18.63 100.53 6.23 13.58 0.03 0.00 0.00 20.41 3.37 44.27 4.70 65.69 1143 9.07 37.30 0.02 0.00 0.01 33.11 4.69 18.63 102.91 6.28 13.43 0.03 0.00 0.01 20.29 4.43 43.34 4.73 65.98 are ordered according to increasing Se content. Table 4. EPMA data for fizélyite. apfu Σ88 Atoms Ag Pb Fe Cd Mn Sb Se S Total Ag Pb Fe Cd Mn Sb Se S N L% 556 6.90 37.65 0.65 0.36 0.07 33.84 0.21 20.84 100.57 4.72 13.39 0.86 0.24 0.09 20.49 0.20 47.91 4.05 58.51 479 6.98 37.56 0.53 0.04 0.07 33.30 0.23 19.93 98.62 4.93 13.80 0.72 0.02 0.10 20.83 0.23 47.32 4.08 59.54 1172 7.46 37.95 0.38 0.00 0.09 33.92 0.25 20.63 100.74 5.12 13.57 0.50 0.00 0.12 20.64 0.24 47.68 4.15 61.58 729 6.71 37.18 0.94 0.01 0.06 33.33 0.32 20.42 99.03 4.65 13.43 1.26 0.01 0.08 20.49 0.30 47.65 4.02 58.00 1903 7.43 37.71 0.45 0.00 0.01 34.19 0.72 20.44 101.05 5.10 13.48 0.60 0.00 0.02 20.79 0.68 47.19 4.10 62.23 2062 7.11 36.56 0.57 0.00 0.03 33.33 1.20 19.25 98.06 5.07 13.58 0.79 0.00 0.04 21.07 1.17 46.22 4.06 61.44 are ordered according to increasing Se content.

Minerals 2019, 9, 430 12 of 47 4.2.5. Andorite IV Ag 15 Pb 18 Sb 47 S 96 Andorite IV is the second most frequent andorite mineral (10 samples, 70 point analyses). It is most often found as grains and inclusions up to 300 µm in Ag-excess fizélyite which is replaced by andorite IV, and also as worm-like relict aggregates associated with andorite VI, occasionally mutually intergrowing, associated with boulangerite, owyheeite, jamesonite, freieslebenite and diaphorite in black ore (i) (Figure 5a,b). Andorite IV is sometimes as lamellae as much as 150 µm long and 30 µm wide. According to the degree of replacement, only amoebic relics, frayed or ragged at the edges, remain. The earliest mineral in the association is galena, followed by andorite IV, which is replaced by andorite VI, which are corroded by owyheeite and fizélyite. Thus, this is an opposite trend to the general succession. Chemical analyses of andorite IV (Table 5, Figure 3) revealed N chem values between 3.88 and 4.09 Minerals (mean2019, 3.96) 9, and x FOR L% PEER (percentage REVIEW of the andorite 2Pb = Ag + Sb substitution) between 90.21 and 13 97.21 of 45 (mean 94.18), which is in a good agreement with published data of this mineral phase [41]. The SeS 1 substitution does not exceed 3.24Table apfu (1.76 6. EPMA data Se) for (Figure andorite 6). VI. apfu Ʃ11 Atoms 4.2.6. Andorite VI, AgPbSb 3 S Ag Pb Fe Sb 6 As Se S Total Ag Pb Fe Sb As Se S N L% 1273 Andorite 11.75 VI 24.02 is much 0.07 41.89 less frequent 0.08 0.14 than 22.08 andorite 100.02 IV 0.95 (171.01 point 0.01 analyses 3.00 0.01 of four 0.02 samples). 6.00 3.86 It 100.07 was 1300 11.84 23.07 0.09 41.32 0.05 0.21 22.12 98.70 0.96 0.98 0.01 2.97 0.01 0.02 6.04 3.90 100.67 found in black ore (i) as anhedral grains up to 80 µm in earlier Ag-excess fizélyite, which is replaced by 2075 11.99 23.36 0.07 41.56 0.00 0.22 21.27 98.47 0.99 1.01 0.01 3.04 0.00 0.02 5.91 3.92 100.50 andorite 1299 IV, 12.11 which 23.64 is then 0.06 replaced 42.03 0.07 by0.23 andorite 22.10 VI, 100.22 and, 0.97 occassionally, 0.99 0.01 as 3.00 anhedral 0.01 0.02 grains 5.98 up3.93 to 250 100.36 µm in2076 earlier11.88 Ag-excess 23.15 fizélyite 0.06 41.68 with0.00 all or 0.24 most 21.42 of andorite 98.43 0.98 IV being 0.99 0.01 replaced 3.04 by 0.00 andorite 0.03 5.94 VI (Figure 3.87 101.52 5b). It1291 is the mineral 11.89 23.48 with0.10 the highest 41.88 0.02 andorite 0.26 substitution 22.12 99.75 (2Pb 0.96 = 0.99 Ag 0.02 + Sb), 2.99 i.e. 0.00 the lowest 0.03 6.00 Pb and 3.89 highest 100.69 1769 11.95 24.51 0.08 41.89 0.15 0.32 21.93 100.83 0.96 1.03 0.01 2.99 0.02 0.03 5.94 3.91 98.87 Ag and Sb contents, and it appears as the latest mineral in the association of andorite group minerals. 1745 12.08 23.78 0.07 41.83 0.17 0.34 21.83 100.09 0.98 1.00 0.01 3.00 0.02 0.04 5.94 3.92 100.30 2065 Chemical 12.03 composition 23.45 0.07 41.67 of andorite 0.00 0.88 VI20.97 and corresponding 99.07 0.99 1.01 chemical 0.01 3.05 formulae 0.00 0.10 are given 5.83 3.93 in Table 100.426. N2164 chem values 11.913.80 4.02 23.25 0.05 (mean 41.533.91) 0.00 and 0.94 the21.02 andorite 98.70 substitution 0.98 1.00 percentage 0.01 3.04 0.00 (L%) 0.11 97.4 102.2 5.84 3.90 (Figure 100.863) correspond 2166 11.80 to the 23.69 published 0.07 40.92 data0.00 of this 1.31 mineral 20.47 [41]. 98.26 The 0.99 Se 1.03 for S0.01 substitution 3.04 0.00 is similar 0.15 5.77 to andorite 3.95 98.91 IV and does not exceed 0.15 apfu (1.31 are ) ordered (Figure according 6). to increasing Se content. 4.2.7. Owyheeite, Ag3Pb10Sb11S28 3 11 S 28 Owyheeite occurs as massive needle-like steel to to lead grey aggregates up up to to 2 cm 2 cm long long in quartz in quartz and and kutnohorite associated associated or intergrowing or intergrowing with massive with massive boulangerite, boulangerite, miargyrite miargyrite and pyrite. and Itpyrite. occurs It in occurs black ore in (i) black associated ore (i) with associated galena, Pb-Sb with sulfosalts galena, Pb-Sb (boulangerite, sulfosalts jamesonite) (boulangerite, and Ag-Pb-Sb jamesonite) sulfosalts and Ag-Pb-Sb (andorite group sulfosalts minerals, (andorite freieslebenite group minerals, and diaphorite) freieslebenite (Figure 5c,d). and diaphorite) It is frequent(figure in polished 5c,d). sections It is frequent (160 point analyses). polished sections It was found (160 point as elongated analyses). lamellae It was found up to 100 as elongated µm in length lamellae and 20 up µmto in 100 width μm in forming length massive and 20 μm grains width several forming hundred massive microns grains across. several hundred microns across. The chemical composition of owyheeite (Table 7) is close to ideal formula Ag Ag3Pb10Sb11S28 3 11 S 28 proposed by Moëlo et etal. [44], with a slight deficit of Pb and an excess of Sb. Figure 7 shows that contents of ofmain elements Ag, Pb and Sb do not correlate significantly and the 2Pb Ag Ag + Sb Sb substitution presentedby by Moëloet etal. al. [45] is isnot notthe the dominant factorin inthe chemical compositionof of owyheeite. The The determined contentsof of seleniumin inthe the studied mineralare are relativelylow low (0.12 1.17 apfu; 0.21 1.97 ). Its Its average average composition (113 (113 analyses) analyses) is possible is possible to express to express by empirical by empirical formula formula (Ag (Ag2.96Cu0.03)Σ2.99(Pb9.63Fe0.02)Σ9.65(Sb11.18As0.03)Σ11.21(S27.73Se0.36Cl0.04)Σ28.13 2.96 Cu 0.03 ) Σ2.99 (Pb 9.63 0.02 ) Σ9.65 (Sb 11.18 As 0.03 ) Σ11.21( S 27.73 Se 0.36 Cl 0.04 ) Σ28.13 on the on the basis basis of 52 ofapfu. 52 apfu. 11.8 11.6 (a) 10.2 10.0 (b) Sb+As (apfu) 11.4 11.2 11.0 Pb+Fe (apfu) 9.8 9.6 10.8 9.4 10.6 9.2 9.4 9.6 9.8 10.0 10.2 9.2 2.7 2.8 2.9 3.0 3.1 3.2 3.3 Pb+Fe (apfu) Ag+Cu (apfu)

Minerals 2019, 9, 430 13 of 47 Table 5. EPMA data for andorite IV. apfu Σ88 Atoms Ag Pb Fe Sb As Se S Total Ag Pb Fe Sb As Se S N L% 947 11.28 25.41 0.13 40.50 0.00 0.22 21.77 99.31 3.69 4.33 0.08 11.75 0.01 0.10 23.97 3.95 94.65 1160 11.54 25.95 0.19 40.72 0.07 0.30 22.03 100.79 3.72 4.36 0.12 11.64 0.03 0.13 23.92 4.02 93.28 1899 11.29 26.58 0.16 40.80 0.08 0.36 21.62 100.87 3.68 4.51 0.10 11.77 0.04 0.16 23.69 3.96 92.96 953 10.99 25.94 0.06 40.02 0.00 0.37 21.34 98.71 3.65 4.48 0.04 11.76 0.02 0.17 23.81 3.93 93.79 1742 11.28 26.02 0.11 40.57 0.14 0.45 21.60 100.18 3.69 4.43 0.07 11.75 0.07 0.20 23.75 3.95 94.22 1743 11.21 26.06 0.12 40.06 0.17 0.45 21.45 99.52 3.69 4.47 0.08 11.68 0.08 0.20 23.75 3.97 93.31 950 11.16 25.48 0.12 40.40 0.06 0.46 21.47 99.14 3.68 4.37 0.07 11.79 0.03 0.21 23.79 3.92 94.78 1722 11.05 26.62 0.07 40.34 0.12 0.52 21.29 100.00 3.64 4.57 0.05 11.78 0.05 0.23 23.61 3.92 93.13 1586 11.07 27.03 0.14 39.41 0.17 0.61 20.99 99.42 3.69 4.69 0.09 11.62 0.08 0.28 23.51 4.01 91.59 1587 11.18 26.91 0.06 40.35 0.13 0.62 21.25 100.49 3.68 4.61 0.04 11.76 0.06 0.28 23.51 3.94 93.21 2146 11.44 25.55 0.12 39.72 0.00 0.90 20.92 98.65 3.81 4.44 0.08 11.73 0.00 0.41 23.47 4.07 92.95 2156 11.37 25.36 0.13 39.71 0.00 1.20 20.64 98.41 3.81 4.43 0.08 11.80 0.00 0.55 23.29 4.04 93.40 2155 11.46 25.34 0.10 39.71 0.00 1.76 20.26 98.63 3.86 4.44 0.07 11.84 0.00 0.81 22.95 4.07 93.54 are ordered according to increasing Se content. Table 6. EPMA data for andorite VI. apfu Σ11 Atoms Ag Pb Fe Sb As Se S Total Ag Pb Fe Sb As Se S N L% 1273 11.75 24.02 0.07 41.89 0.08 0.14 22.08 100.02 0.95 1.01 0.01 3.00 0.01 0.02 6.00 3.86 100.07 1300 11.84 23.07 0.09 41.32 0.05 0.21 22.12 98.70 0.96 0.98 0.01 2.97 0.01 0.02 6.04 3.90 100.67 2075 11.99 23.36 0.07 41.56 0.00 0.22 21.27 98.47 0.99 1.01 0.01 3.04 0.00 0.02 5.91 3.92 100.50 1299 12.11 23.64 0.06 42.03 0.07 0.23 22.10 100.22 0.97 0.99 0.01 3.00 0.01 0.02 5.98 3.93 100.36 2076 11.88 23.15 0.06 41.68 0.00 0.24 21.42 98.43 0.98 0.99 0.01 3.04 0.00 0.03 5.94 3.87 101.52 1291 11.89 23.48 0.10 41.88 0.02 0.26 22.12 99.75 0.96 0.99 0.02 2.99 0.00 0.03 6.00 3.89 100.69 1769 11.95 24.51 0.08 41.89 0.15 0.32 21.93 100.83 0.96 1.03 0.01 2.99 0.02 0.03 5.94 3.91 98.87 1745 12.08 23.78 0.07 41.83 0.17 0.34 21.83 100.09 0.98 1.00 0.01 3.00 0.02 0.04 5.94 3.92 100.30 2065 12.03 23.45 0.07 41.67 0.00 0.88 20.97 99.07 0.99 1.01 0.01 3.05 0.00 0.10 5.83 3.93 100.42 2164 11.91 23.25 0.05 41.53 0.00 0.94 21.02 98.70 0.98 1.00 0.01 3.04 0.00 0.11 5.84 3.90 100.86 2166 11.80 23.69 0.07 40.92 0.00 1.31 20.47 98.26 0.99 1.03 0.01 3.04 0.00 0.15 5.77 3.95 98.91 are ordered according to increasing Se content.

Minerals 2019, 9, 430 14 of 47 Table 7. EPMA data for owyeeite. apfu Σ52 Atoms Ag Pb Fe Sb As Se S Total Ag Cu Pb Fe Sb As Se S 822 6.70 44.08 0.09 28.90 0.00 0.21 19.34 99.32 2.88 0.03 9.86 0.08 11.00 0.03 0.12 27.95 1004 6.81 43.21 0.00 29.59 0.07 0.54 19.50 99.72 2.90 0.01 9.56 0.03 11.15 0.04 0.31 27.89 1193 6.87 43.79 0.05 29.42 0.00 1.14 19.45 100.72 2.90 0.02 9.63 0.04 11.01 0.02 0.66 27.65 1190 6.92 43.69 0.11 29.51 0.00 0.93 19.36 100.51 2.93 0.03 9.64 0.09 11.09 0.01 0.54 27.61 1195 6.98 44.06 0.00 29.80 0.07 0.96 19.45 101.32 2.94 0.02 9.67 0.02 11.13 0.04 0.55 27.58 1192 6.97 43.36 0.05 29.55 0.08 1.09 19.26 100.35 2.96 0.01 9.59 0.04 11.12 0.05 0.63 27.53 1191 6.98 43.51 0.00 29.50 0.06 1.04 19.30 100.38 2.96 0.01 9.62 0.03 11.10 0.04 0.60 27.58 1194 7.06 43.39 0.00 29.51 0.07 1.11 19.26 100.41 3.00 0.02 9.59 0.03 11.10 0.04 0.64 27.51 1188 7.10 43.64 0.08 29.76 0.00 0.97 19.31 100.87 3.01 0.02 9.62 0.07 11.16 0.02 0.56 27.50 712 7.19 43.18 0.26 29.58 0.07 0.93 19.29 100.51 3.04 0.03 9.52 0.21 11.09 0.04 0.54 27.47 1511 7.14 43.05 0.00 29.52 0.12 1.09 18.95 99.86 3.06 0.03 9.60 0.02 11.20 0.07 0.64 27.31 1698 7.23 44.14 0.00 28.86 0.16 0.42 19.40 100.20 3.08 0.06 9.78 0.01 10.89 0.10 0.24 27.79 1503 7.24 42.30 0.07 29.70 0.09 0.93 19.10 99.43 3.09 0.03 9.41 0.06 11.24 0.06 0.55 27.45 1512 7.24 42.51 0.00 29.69 0.19 1.63 18.79 100.03 3.10 0.01 9.47 0.00 11.26 0.12 0.95 27.05 2095 7.47 42.21 0.00 30.38 0.00 0.44 19.35 99.85 3.18 0.02 9.35 0.03 11.45 0.00 0.26 27.69 are ordered according to increasing Ag content.

Pb+Fe (at. %) Sb+As (at. %) contents of main elements Ag, Pb and Sb do not correlate significantly and the 2Pb Ag + Sb substitution presented by Moëlo et al. [45] is not the dominant factor in the chemical composition of owyheeite. The determined contents of selenium in the studied mineral are relatively low (0.12 1.17 apfu; 0.21 1.97 ). Its average composition (113 analyses) is possible to express by empirical formula (Ag2.96Cu0.03)Σ2.99(Pb9.63Fe0.02)Σ9.65(Sb11.18As0.03)Σ11.21(S27.73Se0.36Cl0.04)Σ28.13 on the basis of 52 apfu. Minerals 2019, 9, 430 15 of 47 11.8 11.6 (a) 10.2 10.0 (b) Sb+As (apfu) 11.4 11.2 11.0 Pb+Fe (apfu) 9.8 9.6 10.8 9.4 10.6 9.2 9.4 9.6 9.8 10.0 10.2 9.2 2.7 2.8 2.9 3.0 3.1 3.2 3.3 Pb+Fe (apfu) Ag+Cu (apfu) Figure 7. Graph Ag + Cu vs Sb + As (apfu) (a) and Ag + Cu vs Pb + Fe (apfu) (b) for owyheeite. Figure 7. Graph Ag + Cu vs Sb + As (apfu) (a) and Ag + Cu vs Pb + Fe (apfu) (b) for owyheeite. 4.2.8. Ag-Poor Ag-Pb-Sb Sulfosalts Ag-poor Ag-Pb-Sb sulfosalts are chemically similar to owyheeite, but show lower contents of Ag and higher contents of Pb. Most often it forms lamellae several tens of microns across enclosed in owyheeite or boulangerite, which it replaces (in agreement with the general succession) (Figure 8). It is closely associated with owyheeite, boulangerite, galena, jamesonite and Ag-excess fizélyite. It is much rarer than owyheeite (21 point analyses, compared to 160 analyses of owyheeite). Minerals 2019, 9, x FOR PEER REVIEW 15 of 45 Bou Jms Aps Jms Bou 30 m Figure 8. Grain of Ag-poor Ag-Pb-Sb sulfosalt (Aps, 3.3 Ag) in boulangerite (Bou) in association with jamesonite (Jms), Ag-excess fizélyite () and galena (). The succession runs as: galena boulangerite jamesonite Ag-poor Ag-Pb-Sb sulfosalt Ag-excess fizélyite. The Ag-poor part (with Ag contents lower than in the case of owyheeite) is an interestingand so far not a well-known part of theag-pb-sb-s system,with only two approved minerals questionable 32 24 zoubekite (a) [45,46] and tubulite with unusual tubular (b) morphology and crystal structure [47]. Ag-poor Ag-Pb-Sb sulfosalts, this paper 30 owyheeite, this paper We identified mineral 22 M3 28 Ag-poor phases Ag-Pb-Sb sulfosalts, with published 0.7 4.3 dataat.% Ag (0.87 5.12 Ag), which can be divided into four groups of compositions (Table 8) differing by Ag content: a) four analyses with 0.87 1.16 boulangerite zoubekite 26 boulangerite UM1979-14 20 T of Ag; b) nine analyses with 2.02 2.87 Ag; c) four analyses with 3.31 4.29 ; M2 and d) four 24 T analyses with 5.08 5.20. The determined UM1990-32 Ag and 18 Pb contents show negative correlation with 22 M2 UM1979-14 UM1990-32 M3 zoubekite 20 16 Ag-poor Ag-Pb-Sb sulfosalts, this paper owyheeite, this paper 18 Ag-poor Ag-Pb-Sb sulfosalts, published data 16 0 1 2 3 4 5 6 7 Ag+Cu (at. %) 14 0 1 2 3 4 5 6 7 Ag+Cu (at. %)

Pb+Fe (at. %) Sb+As (at. %) as massive needle-like steel to lead grey aggregates up to 2 cm long in quartz iated or intergrowing with massive boulangerite, miargyrite and pyrite. It ) associated with galena, Pb-Sb sulfosalts (boulangerite, jamesonite) and ndorite group minerals, freieslebenite and diaphorite) (Figure 5c,d). It is Minerals 2019, 9, 430 16 of 47 ctions (160 point analyses). It was found as elongated lamellae up to 100 μm width forming massive grains several hundred microns across. position of owyheeite ratio ca. (Table 1:1 (Figure 7) is 9a); close a less to pronounced ideal formula positive Ag3Pb10Sb11S28 correlation was found between Ag and Sb with al. [44], with a slight ratio ca. deficit 2:1 (Figure of Pb and 9b). an Both excess correlations of Sb. Figure in principle 7 shows fit the that line between zoubekite and boulangerite. ents Ag, Pb and The Sb substitution do not correlate scheme significantly be expressed and the as2pb Ag + 0.5Sb. The chemical composition of found by Moëlo et al. [45] Ag-poor is not the Ag-Pb-Sb dominant sulfosalts factor in is close the chemical to two mineral composition phases: of the recently described mineral tubulite ined contents of selenium Ag 2 Pb 22 Sb in 20 the S 53 studied, which, mineral however, are differs relatively in itslow very(0.12 1.17 unusual and specific tube-like morphology [47]; Its average composition and an unnamed (113 analyses) phaseis M3 possible with the to express ideal formula by empirical AgPb 11 Sb 11 S 26 described by Megerskaja and 99(Pb9.63Fe0.02)Σ9.65(Sb11.18As0.03)Σ11.21(S27.73Se0.36Cl0.04)Σ28.13 Rykl Minerals [48] 2019, from9, x Příbram, FOR PEER Czech REVIEW Republic. on the basis Other of unnamed 52 apfu. phases in this system differ first of 15 allof by45 having higher Pb contents and lower Sb (Figure 9a,b). The Se contents found in Ag-poor Ag-Pb-Sb sulfosalts are relatively low, within 0.22 1.54 at.% (0.18 1.35 Se). The chemical compositions and 10.2 corresponding formula coefficients calculated for 52 apfu (as in owyheeite) are given in Table 8. Pb+Fe (apfu) 10.0 (b) Jms Table 8. EPMA data for Ag-poor Ag-Pb-Sb sulfosalts. Bou 9.8 wt% apfu Σ52 Atoms Aps Ag Pb Fe Sb As Se S Total Ag Cu Pb Fe Sb As Se S 9.6 495 0.87 49.27 1.95 27.19 0.00 0.32 19.84 Jms 99.43 0.37 0.01 10.93 1.60 10.27 0.02 0.19 28.44 1513 1.05 52.45 0.09 27.14 0.10 0.95 18.81 100.59 0.46 0.01 12.01 0.08 10.58 0.06 0.57 27.83 9.4 1325 1.17 52.47 0.46 26.70 0.00 0.55 18.94 100.29 0.52 0.02 12.06 0.39 10.45 0.02 0.33 28.14 904 1.18 51.61 0.00 28.04 0.00 0.44 18.37 99.63 0.53 0.01 12.10 0.03 11.18 0.00 0.27 27.82 9.2 1559 2.02 51.78 0.00 27.01 0.09 0.37 18.33 99.60 0.91 Bou 0.02 12.15 0.02 10.78 0.06 0.23 27.78 9.6 9.8 10.0 10.2 2.7 2.8 2.9 3.0 3.1 3.2 3.3 323 2.03 50.64 0.00 27.45 0.05 0.25 18.53 98.95 0.91 0.01 11.84 0.03 10.92 0.03 0.16 28.00 Pb+Fe (apfu) 991 2.21 50.36 0.00 27.19 0.00 Ag+Cu 0.91 (apfu) 18.82 99.49 0.98 0.00 11.62 0.02 10.68 0.03 0.55 28.07 490 2.36 47.86 0.94 28.64 0.05 0.36 19.53 99.73 1.01 0.01 10.69 0.78 10.89 0.03 0.21 28.19 321 2.26 48.55 0.07 27.80 0.10 0.18 18.68 97.64 1.01 0.00 11.36 0.06 11.07 0.06 0.11 28.24 1502 2.48 50.13 0.12 28.26 0.10 1.35 18.87 101.30 1.08 0.00 11.32 0.10 10.86 0.06 0.80 27.53 Ag + Cu vs Sb + As (apfu) (a) and Ag + Cu vs Pb + Fe (apfu) (b) for owyheeite. 580 2.71 48.99 0.06 28.36 0.00 0.70 19.12 99.95 1.19 0.00 11.15 0.05 10.98 0.02 0.42 28.11 2227 2.69 50.88 0.06 26.61 0.00 0.20 18.81 99.25 1.20 0.02 11.81 0.05 10.51 0.00 0.12 28.22 891 2.87 47.51 0.12 29.17 0.00 0.48 19.37 99.52 1.25 0.01 10.75 0.10 11.23 0.00 0.29 28.32 2774 3.31 47.97 0.00 27.86 0.00 0.27 18.82 98.23 1.47 0.06 11.11 0.01 10.98 0.02 0.17 28.17 2775 3.53 47.84 0.00 28.02 0.07 0.29 18.66 98.41 1.57 0.08 11.09 300.00 m 11.05 0.05 0.18 27.95 578 3.92 46.80 0.00 29.39 0.05 0.42 18.77 99.34 1.72 0.01 10.71 0.04 11.44 0.03 0.25 27.75 895 4.29 45.97 0.00 28.46 0.00 0.51 18.90 98.12 1.89 0.02 10.55 0.02 11.12 0.01 0.31 28.04 1003 5.08 44.78 0.00 28.62 0.06 0.52 19.22 98.27 2.21 0.03 10.14 0.03 11.03 0.03 0.31 28.13 992Figure 5.12 8. Grain 43.91 of 0.06 Ag-poor 30.87Ag-Pb-Sb 0.06 0.89 sulfosalt 19.28 (Aps, 100.18 3.3 2.18 Ag) 0.05in boulangerite 9.76 0.05 11.67 (Bou) in 0.04 association 0.52 27.69 1389 5.16 43.81 0.09 30.32 0.00 0.39 20.05 99.82 2.18 0.00 9.63 0.07 11.34 0.02 0.22 28.47 with jamesonite (Jms), Ag-excess fizélyite () and galena (). The succession runs as: galena 909 5.20 44.51 0.00 28.46 0.00 0.55 18.90 97.62 2.29 0.01 10.20 0.01 11.09 0.02 0.33 27.98 boulangerite jamesonite Ag-poor Ag-Pb-Sb sulfosalt Ag-excess fizélyite. are ordered according to increasing Ag content. 32 30 28 (a) Ag-poor Ag-Pb-Sb sulfosalts, this paper owyheeite, this paper Ag-poor Ag-Pb-Sb sulfosalts, published data 24 22 (b) M3 26 24 22 20 18 16 boulangerite M3 T UM1979-14 0 1 2 3 4 5 6 7 Ag+Cu (at. %) M2 UM1990-32 zoubekite 20 18 16 14 boulangerite T UM1979-14 zoubekite Ag-poor Ag-Pb-Sb sulfosalts, this paper owyheeite, this paper Ag-poor Ag-Pb-Sb sulfosalts, published data UM1990-32 0 1 2 3 4 5 6 7 Ag+Cu (at. %) M2 Figure 9. 9.(a) Graph Ag + Cu vs Pb + Fe (at.%) for for Ag-poor Ag-Pb-Sb sulfosalts and and owyheeite; boulangerite ideal compositionpb5sb4s11; 5 4 S 11 T-tubulite ; T-tubulite ideal ideal composition composition Ag2Pb22Sb20S53[47]; 2 22 20 Sunnamed 53 [47]; unnamed M3 Příbram M3 Příbram [48]; unnamed [48]; unnamed M2 Příbram M2 Příbram [48]; [48]; UM1979-14 Primorye [49,50]; UM1990-32; zoubekite ideal composition AgPb4Sb4S10 AgPb 4 Sb 4 S 10 [46].(b) [46].(b) graph graphag Ag + Cu + Cu vs. Sb vs. + As Sb (at.%) + As for (at.%) Ag-poor for Ag-poor Ag-Pb-Sb Ag-Pb-Sb sulfosalts sulfosalts and owyheeite; and owyheeite; boulangerite boulangerite ideal ideal composition composition Pb5Sb4S11; 5 Sb 4 T-tubulite S 11 ; T-tubulite ideal ideal composition composition Ag Ag2Pb22Sb20S53 2 Pb 22 Sb 20 [47]; S 53 [47]; unnamed unnamed M3 Příbram M3 Příbram [48]; [48]; unnamed M2 Příbram [48]; [48]; UM1979-14 Primorye [49]; [49]; UM1990-32 UM1990-32 [50]; [50]; zoubekite zoubekite ideal ideal composition composition AgPb AgPb4Sb4S10 4 Sb 4 S 10 [46]. [46].

Minerals 2019, 9, 430 17 of 47 4.3. Pb-Sb Sulfosalts 4.3.1. Boulangerite, Pb 5 Sb 4 S 11 Boulangerite occurs as abundant lead grey felt-like aggregates and needle crystals in quartz cavities up to 1 cm or as massive grain needle-like aggregates several cm in size associated with galena and miargyrite in black ore type (i). In polished sections (170 point analyses), it occurs as needle-like and column-like crystals up to 80 µm in length and 10 µm in width associated with galena, freislebenite, jamesonite, andorite group minerals and pyrite (Figure 2a,b, Figure 5c, Figure 8, Figure 10a,b) of black ore (i). Also occurs as lenses in white quartz of ore (iii) consisting of massive fibrous and needle-like grains associated with jamesonite and galena. It belongs to the earliest minerals in the observed mineral associations, next to galena. Minerals 2019, 9, x FOR PEER REVIEW 17 of 45 (a) (b) Bou Bou Bou Bou Bou Dia Sms Frs Dia Bou 20 m 50 m Figure 10. (a) Ag-excess fizélyite () replaces boulangerite (Bou) of black ore (i). (b) earliest galena () Figure replaced 10. (a) Ag-excess by boulangerite fizélyite (Bou) () and replaces semseyite boulangerite (Sms); (Bou) semseyite of black wasore subsequently (i). (b) earliest replaced galena by freieslebenite () replaced (Frs) by boulangerite and diaphorite (Bou) (Dia). and Both semseyite back-scattered (Sms); semseyite electron was (BSE) subsequently images. replaced by freieslebenite (Frs) and diaphorite (Dia). Both back-scattered electron (BSE) images. The chemical composition of boulangerite (Table 9) is close to ideal stoichiometry; only traces of Fe, Mn and Ag were identified. In anion, contents of Se up to 0.63 apfu (2.69) (Figure 11) were observed, which is significantly more than in other Pb-Sb sulfosalts (jamesonite, semseyite). Its 0.26 average composition (167 analyses) is possible to express by the empirical formula (Pb 4.89 Fe 0.01 Mn 0.01 ) Σ4.92 Sb 4.03( S 10.89 Se 0.12 ) Σ11.01 on the basis of 20 apfu. 0.24 Pb/total 0.22 Table 9. EPMA data for boulangerite. Ag 0.20 Pb Fe Mn Sb As Se S Total Ag Pb Fe Mn Sb As Se S 2468 0.00 55.00 0.16 0.15 25.47 0.00 0.00 18.50 99.28 0.00 5.02 0.05 0.05 3.96 0.00 0.00 10.91 2475 0.00 54.56 0.00 0.06 26.35 0.00 0.04 18.89 99.90 0.00 4.92 0.01 0.02 4.04 0.00 0.01 11.00 0.18 2226 0.25 54.29 0.11 0.06 26.35 0.00 0.09 18.71 99.86 0.04 boulangerite 4.90 0.04 0.02 4.05 0.00 0.02 10.92 368 0.00 54.52 0.00 0.00 26.17 0.09 0.24 18.74 99.76 0.01 semseyite 4.92 0.00 0.01 4.02 0.02 0.06 10.93 1644 0.12 55.08 0.16 0.00 0.00 25.10 0.10 0.31 18.54 99.24 0.02 5.03 0.00 0.01 3.90 0.02 0.07 10.94 jamesonite 1855 0.00 54.74 0.00 0.00 26.35 0.08 0.59 18.64 100.39 0.00 4.93 0.00 0.00 4.04 0.02 0.14 10.85 1940 0.00 54.80 0.00 0.05 26.81 0.05 0.61 18.90 101.21 0.00 4.88 0.01 0.02 4.06 0.01 0.14 10.87 718 0.05 53.97 0.14 0.00 0.00 26.04 0.00 0.85 18.73 99.64 0.01 4.86 0.01 0.01 3.99 0.01 0.20 10.90 581 0.00 55.21 0.00 0.00 0.0026.12 0.00 0.02 1.07 18.59 0.04 101.000.06 0.00 4.950.08 0.00 0.01 0.10 3.99 0.01 0.25 10.78 757 0.00 54.13 0.17 0.00 25.62 0.00 1.93 18.25 100.09 0.00 4.89 0.06 0.01 3.93 0.00 0.46 10.64 1515 0.00 54.01 0.10 0.09 26.29 0.06 2.21Se/(Se+S) 18.07 100.84 0.00 4.85 0.03 0.03 4.01 0.02 0.52 10.48 748 0.00 54.27 0.06 0.00 26.17 0.00 2.69 18.12 101.30 0.01 4.86 0.02 0.01 3.99 0.00 0.63 10.48 Figure 11. Graph Se/(Se + S) (apfu) vs Pb/total apfu for Pb-Sb sulfosalts. are ordered according to increasing Se content. Table 9. EPMA data for boulangerite. apfu Σ20 Atoms apfu Ʃ20 Atoms Ag Pb Fe Mn Sb As Se S Total Ag Pb Fe Mn Sb As Se S 2468 0.00 55.00 0.16 0.15 25.47 0.00 0.00 18.50 99.28 0.00 5.02 0.05 0.05 3.96 0.00 0.00 10.91 2475 0.00 54.56 0.00 0.06 26.35 0.00 0.04 18.89 99.90 0.00 4.92 0.01 0.02 4.04 0.00 0.01 11.00 2226 0.25 54.29 0.11 0.06 26.35 0.00 0.09 18.71 99.86 0.04 4.90 0.04 0.02 4.05 0.00 0.02 10.92 368 0.00 54.52 0.00 0.00 26.17 0.09 0.24 18.74 99.76 0.01 4.92 0.00 0.01 4.02 0.02 0.06 10.93 1644 0.12 55.08 0.00 0.00 25.10 0.10 0.31 18.54 99.24 0.02 5.03 0.00 0.01 3.90 0.02 0.07 10.94

Figure 10. (a) Ag-excess fizélyite () replaces boulangerite (Bou) of black ore (i). (b) earliest galena () replaced by boulangerite (Bou) and semseyite (Sms); semseyite was subsequently replaced by freieslebenite (Frs) and diaphorite (Dia). Both back-scattered electron (BSE) images. Minerals 2019, 9, 430 18 of 47 0.26 0.24 0.22 Pb/total 0.20 0.18 0.16 boulangerite semseyite jamesonite 0.14 0.00 0.02 0.04 0.06 0.08 0.10 Se/(Se+S) 4.3.2. Semseyite, Pb 9 Sb 8 S 21 Figure 11. 11. Graph Se/(Se + S) + S) (apfu) vs vs Pb/total apfu apfu for for Pb-Sb sulfosalts. Table 9. EPMA data for boulangerite. Semseyite was found in a similar association as boulangerite, but is much apfu Ʃ20 rarer, Atoms it usually occurs as needle-like Ag or tabular Pb Fe grain Mn up to Sb 20 µm As inse length S andtotal 15 µmag in width Pb Fe (Figure Mn 10b). Sb The As chemical Se S composition 2468 0.00 of semseyite 55.00 0.16 (Table 0.1510) 25.47 corresponds 0.00 0.00 to ideal 18.50 stoichiometry 99.28 0.00 5.02 of this 0.05 mineral 0.05 3.96 phase; 0.00 Ag 0.00 content 10.91 2475 0.00 54.56 0.00 0.06 26.35 0.00 0.04 18.89 99.90 0.00 4.92 0.01 0.02 4.04 0.00 0.01 11.00 in one point analysis (0.19 apfu) can be influenced by the surrounding phases. Unlike other Pb-Sb 2226 0.25 54.29 0.11 0.06 26.35 0.00 0.09 18.71 99.86 0.04 4.90 0.04 0.02 4.05 0.00 0.02 10.92 sulfosalts, semseyite is virtually Se-free (Figure 11). Its empirical formula (mean of 4 analyses) is 368 0.00 54.52 0.00 0.00 26.17 0.09 0.24 18.74 99.76 0.01 4.92 0.00 0.01 4.02 0.02 0.06 10.93 (Pb 8.91 1644 Ag 0.05 0.12 ) Σ8.96 55.08 Sb 7.95 0.00 S 21.08 0.00 on the 25.10 basis 0.10 of 38 0.31 apfu. 18.54 99.24 0.02 5.03 0.00 0.01 3.90 0.02 0.07 10.94 1855 0.00 54.74 0.00 0.00 26.35 0.08 0.59 18.64 100.39 0.00 4.93 0.00 0.00 4.04 0.02 0.14 10.85 1940 0.00 54.80 0.00 0.05 26.81 Table0.05 10. EPMA 0.61 data 18.90 for 101.21 semseyite. 0.00 4.88 0.01 0.02 4.06 0.01 0.14 10.87 718 0.05 53.97 0.00 0.00 26.04 0.00 0.85 18.73 99.64 0.01 4.86 0.01 0.01 3.99 0.01 0.20 10.90 581 0.00 55.21 0.00 0.00 26.12 0.00 1.07 18.59 101.00 apfu 0.00 Σ38 4.95 Atoms 0.00 0.01 3.99 0.01 0.25 10.78 757 0.00 54.13 0.17 0.00 25.62 0.00 1.93 18.25 100.09 0.00 4.89 0.06 0.01 3.93 0.00 0.46 10.64 Ag Pb Sb S Total Ag Pb Sb S 1515 0.00 54.01 0.10 0.09 26.29 0.06 2.21 18.07 100.84 0.00 4.85 0.03 0.03 4.01 0.02 0.52 10.48 748 0.00 54.27 2462 0.06 0.00 26.17 52.82 0.00 27.462.69 19.53 18.12 99.92 101.30 0.00 0.01 4.86 8.89 0.02 7.870.01 21.24 3.99 0.00 0.63 10.48 2482 0.57 50.70 are ordered 27.18 according 19.18 97.63 to increasing 0.19 8.68 Se content. 7.92 21.22 2483 0.00 52.41 27.04 18.81 98.42 0.00 9.05 7.95 21.00 2463 0.00 52.71 27.72 18.85 99.46 0.00 9.02 8.07 20.84 4.3.3. Jamesonite, Pb 4 FeSb 6 S 14 Jamesonite occurs as needle crystals in quartz gangue or as massive grain needle-like aggregates up to 2 cm in black ore (i) and ore (iii). In the polished section, it was found as long needles up to 150 µm in length and 20 µm in width. It usually replaces galena and grows together with boulangerite, freibergite and pyrite (Figure 2c, Figure 8). It belongs to the earliest minerals in the association. The chemical composition of jamesonite (100 point analyses) is relatively uniform (Table 11) and close to ideal formula; only minor contents of Mn (up to 0.11 apfu) and Se (up to 0.27 apfu) were identified (Figure 11). The observed range of SeS 1 substitution is distinctly lower than in boulangerite (Figure 11). The empirical formula for studied jamesonite on the basis of 25 apfu (mean of 84 analyses) can be expressed as Fe 0.95 Mn 0.02 ) Σ0.97 Pb 3.94 Sb 6.05 (S 13.94 Se 0.07 ) Σ14.01.

Minerals 2019, 9, 430 19 of 47 Table 11. EPMA data for jamesonite. apfu Σ20 Atoms Pb Fe Mn Sb Se S Total Pb Fe Mn Sb Se S 2450 39.14 2.55 0.09 34.95 0.00 21.77 98.50 3.92 0.95 0.03 5.96 0.00 14.10 379 40.51 2.56 0.00 35.12 0.09 21.90 100.17 4.02 0.94 0.02 5.93 0.02 14.03 213 39.67 2.61 0.00 35.80 0.30 21.22 99.60 3.99 0.98 0.01 6.13 0.08 13.80 864 39.45 2.47 0.06 35.44 0.41 21.70 99.53 3.93 0.91 0.02 6.01 0.11 13.98 1304 39.29 2.62 0.10 35.76 0.43 21.91 100.09 3.88 0.96 0.04 6.01 0.11 13.99 863 39.69 2.41 0.10 36.12 0.44 21.74 100.49 3.93 0.89 0.04 6.08 0.11 13.90 1906 39.24 2.51 0.05 36.05 0.61 21.88 100.34 3.87 0.92 0.02 6.06 0.16 13.96 2069 38.48 2.45 0.14 35.56 0.83 20.81 98.27 3.92 0.93 0.05 6.16 0.22 13.70 are ordered according to increasing Se content. 4.4. Ag-Sb Sulfosalts 4.4.1. Miargyrite, AgSbS 2 Miargyrite is by far the most abundant silver mineral in the Kutná Hora ore district, together with freibergite. Short column-like grey-black crystals of miargyrite up to 10 mm in size in cavities of milky quartz gangue (ore (iii)), or quartz kutnohorite gangue (ore (ii)) are famous from this locality [36]. Frequently, miargyrite forms massive grain aggregates and lenses in all three types of Minerals 2019, 9, x FOR PEER REVIEW 19 of 45 ore of several centimetres in size, often intergrowing with other Ag minerals such as pyrargyrite, diaphorite, freibergite and freieslebenite. In polished sections, it was found as groups of anhedral grains several hundred μm in size and occasional euhedral crystals into cavities. It appears in two grains several hundred µm in size and occasional euhedral crystals into cavities. It appears in two generations at least, the latter being characteristic of a considerably smaller size of grains (up to 20 generations at least, the latter being characteristic of a considerably smaller size of grains (up to 20 µm), μm), higher selenium content (Figure 12a) and the association of members of galena clausthalite higher solid solution. selenium The content two generations (Figure 12a) appear and the in all association three of the of members above-mentioned of galena ores clausthalite (i, ii and iii), solid solution. examples The of miargyrite two generations in black appear ore (i) inare all in three Figures of the 2c e above-mentioned and 12a; red ore ores (ii) in (i, Figures ii and iii), 12b examples and ore of miargyrite (iii) in Figure in black 2f. ore (i) are in Figures 2c e and 12a; red ore (ii) in Figure 12b and ore (iii) in Figure 2f. (a) (b) Sp Dia Mia Dia Mia Sp Agd Py 200 m Py 40 m Figure 12. (a) Galena () the earliest mineral in the association is replaced by diaphorite (Dia), which Figure is12. subsequently (a) Galena () the replaced by earliest Ag-excess mineral fizélyite in the (). association is Both minerals replaced are by replaced diaphorite by miargyrite (Dia), (Mia), which whereas is subsequently miargyrite replaced with1 by Ag-excess Se (darker) fizélyite is replaced (). byboth the the minerals second-generation are replaced Se-rich by miargyrite (lighter, (Mia), 5% whereas Se). (b) miargyrite miargyrite with1 (Mia) embedded Se in (darker) sphalerite is (Sp). replaced An argyrodite by the the (Agd) inclusion second-generation is on the Se-rich boundary miargyrite between (lighter, sphalerite 5% Se). and (b) pyrite miargyrite (Py), (Mia) both embedded minerals (miargyrite in sphalerite and argyrodite) (Sp). An argyrodite replace sphalerite. (Agd) inclusion Both back-scattered is on the boundary electron between (BSE) images. sphalerite and pyrite (Py), both minerals (miargyrite and argyrodite) replace sphalerite. Both back-scattered electron (BSE) images. Chemical analyses of miargyrite (175 points) revealed interesting Se contents (Figure 13a,b), otherwise Chemical it is close analyses to the of miargyrite ideal formula. (175 points) Determined revealed traces interesting of Pb, Cu Se and contents Fe in (Figure some of 13 analyses a,b), otherwise it is close to the ideal formula. Determined traces of Pb, Cu and Fe in some of analyses are probably caused by microscopic intergrowths with other phases; irregular contents of As do not exceed 0.01 apfu (0.19 ). The prevailing earlier generation of miargyrite contains up to 0.08 apfu (2.29 ) of Se; the later generation of miargyrite shows a considerably larger extent of the SeS-1 substitution, usually between 0.11 and 0.35 apfu, corresponding to the maximum Se content of 8.79. Two exceptionally high Se contents were measured in small anhedral grains of miargyrite in

second-generation Se-rich miargyrite (lighter, 5% Se). (b) miargyrite (Mia) embedded in sphalerite (Sp). An argyrodite (Agd) inclusion is on the boundary between sphalerite and pyrite (Py), both minerals (miargyrite and argyrodite) replace sphalerite. Both back-scattered electron (BSE) images. Ag (at. %) Chemical analyses of miargyrite (175 points) revealed interesting Se contents (Figure 13 a,b), Minerals 2019, 9, 430 20 of 47 otherwise it is close to the ideal formula. Determined traces of Pb, Cu and Fe in some of analyses are probably caused by microscopic intergrowths with other phases; irregular contents of As do not are exceed probably 0.01 apfu caused (0.19 by). microscopic The prevailing intergrowths earlier with generation other phases; of miargyrite irregular contains contents up ofto As 0.08 do apfu not exceed (2.29 ) 0.01 apfu of Se; (0.19 the ). later generation The prevailing of miargyrite earlier generation shows a considerably of miargyritelarger contains extent up to of 0.08 the SeS-1 apfu (2.29 substitution, ) ofusually Se; the later between generation 0.11 and of0.35 miargyrite apfu, corresponding shows a considerably to the maximum larger extent Se content of theof SeS 8.79 1 substitution,. Two exceptionally usually between high 0.11 Se and contents 0.35 apfu, were corresponding measured in to small the maximum anhedral grains Se content of miargyrite of 8.79. in Two sphalerite exceptionally of red ore high(ii), Sebelonging contents were to the measured later generation. in small anhedral These show grains 0.57 of and miargyrite 0.62 apfu in sphalerite Se (14.54 of 15.34 red ore (ii), of belonging Se) not toincluded the later generation. in Table 12 These due show to increased 0.57 and Zn 0.62content apfu Se (14.54 15.34 from neighbouring of Se) not sphalerite. included The more in Table significant 12 due contents to increased of Se in Znmiargyrite content from were neighbouring so far described sphalerite. only by Nekrasov, The more significant Lunin [51] contents and Yunfen of Seet inal. miargyrite [52]. The representative were so far described chemical only analyses by Nekrasov, of both Lunin miargyrite [51] and generation Yunfen et and al. corresponding [52]. The representative empirical formulae chemicalare analyses given in of Table both miargyrite 12. generation and corresponding empirical formulae are given in Table 12. Se ( apfu) 0.5 0.4 0.3 0.2 0.1 (a) miargyrite I miargyrite II 60 55 50 45 40 35 30 (b) miargyrite pyrargyrite stephanite polybasite 0.0 25 1.5 1.6 1.7 1.8 1.9 2.0 2.1 S (apfu) 20 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Se/(S+Se) Figure 13. (a) Graph S vs Se (apfu) for two types of miargyrite. (b) graph Se/(S + Se) vs Ag (at.%) for Ag-Sb-S mineral phases. Table 12. EPMA data for miargyrite. apfu Σ4 Atoms Ag Pb Fe Sb As Se S Total Ag Cu Pb Fe Cd Sb As Se S 514 37.18 0.00 0.00 41.06 0.17 0.00 21.83 100.23 1.01 0.00 0.00 0.00 0.00 0.99 0.01 0.00 1.99 52 36.32 0.10 0.06 41.47 0.08 0.33 21.47 99.83 0.99 0.00 0.00 0.00 0.00 1.01 0.00 0.01 1.98 57 35.95 0.23 0.07 40.80 0.13 0.51 21.65 99.34 0.98 0.00 0.00 0.00 0.00 0.99 0.01 0.02 1.99 58 35.99 0.34 0.08 41.10 0.10 0.69 21.32 99.62 0.99 0.00 0.00 0.00 0.00 1.00 0.00 0.03 1.97 8 36.35 0.10 0.00 41.74 0.08 0.88 21.36 100.51 0.99 0.00 0.00 0.00 0.00 1.01 0.00 0.03 1.96 1963 36.13 0.06 0.00 41.81 0.07 1.08 21.05 100.18 0.99 0.00 0.00 0.00 0.00 1.02 0.00 0.04 1.94 791 35.67 0.20 0.06 40.68 0.10 1.76 20.70 99.16 0.99 0.00 0.00 0.00 0.00 1.00 0.00 0.07 1.93 539 36.42 0.08 0.00 41.05 0.07 3.46 20.09 101.18 1.00 0.00 0.00 0.00 0.00 1.00 0.00 0.13 1.86 1137 35.57 0.09 0.00 40.44 0.00 4.26 19.13 99.50 1.00 0.00 0.00 0.00 0.00 1.01 0.00 0.16 1.82 1362 35.16 0.06 0.16 40.10 0.05 4.92 19.53 99.99 0.98 0.00 0.00 0.01 0.00 0.99 0.00 0.19 1.83 1138 34.97 0.40 0.00 40.01 0.00 5.63 18.40 99.40 1.00 0.00 0.01 0.00 0.00 1.01 0.00 0.22 1.76 1265 35.18 0.21 0.08 40.05 0.06 6.35 18.19 100.12 1.00 0.00 0.00 0.00 0.00 1.01 0.00 0.25 1.74 2699 35.18 0.08 0.46 39.06 0.00 8.65 16.85 100.27 1.01 0.00 0.00 0.03 0.00 0.99 0.00 0.34 1.63 2700 34.83 0.06 0.40 38.93 0.00 8.79 16.34 99.34 1.01 0.00 0.00 0.02 0.00 1.00 0.00 0.35 1.60 are ordered according to increasing Se content. 4.4.2. Pyrargyrite, Ag 3 SbS 3 Pyrargyrite crystals up to 5 mm in size and massive grain aggregates several cm in size, occurring (less abundantly than miargyrite) in milky quartz gangue associated with miargyrite and freibergite of ore (iii) or in cavities of the kutnohorite quartz gangue of red ore (ii), associated with other Ag-Sb sulfides and pyrite. Only three samples of pyrargyrite were found in black ore (i) (Figure 2a). In polished sections pyrargyrite was found in nine samples (40 point analyses) as anhedral grains up to 30 µm. It often forms thin veinlets as much as 200 µm in length and 20 µm in width. It occurs as a filling of thin fissures in miargyrite in a close vicinity of Au-rich silver. It also occurs in drop-shaped inclusions of galena in pyrite of red ore (ii) where it replaces galena (Figure 14a). The chemical composition

occurring (less abundantly than miargyrite) in milky quartz gangue associated with miargyrite and freibergite of ore (iii) or in cavities of the kutnohorite quartz gangue of red ore (ii), associated with other Ag-Sb sulfides and pyrite. Only three samples of pyrargyrite were found in black ore (i) (Figure 2a). In polished sections pyrargyrite was found in nine samples (40 point analyses) as Minerals anhedral 2019, grains 9, 430up to 30 μm. It often forms thin veinlets as much as 200 μm in length and 20 μm 21in of 47 width. It occurs as a filling of thin fissures in miargyrite in a close vicinity of Au-rich silver. It also occurs in drop-shaped inclusions of galena in pyrite of red ore (ii) where it replaces galena (Figure of 14a). pyrargyrite The chemical andcomposition the corresponding of pyrargyrite chemical and formulae the corresponding are givenchemical in Tableformulae 13. In comparison are given in to miargyrite Table 13. In and comparison stephanite to (Figure miargyrite 13b), and the stephanite determined(figure range of 13b), SeSthe 1 substitution determined in range pyrargyrite of SeS-1 is limited, substitution maximum in pyrargyrite is 0.13 apfu is limited, (1.82 ) maximum in one analysis, 0.13 apfu but(1.82 in all) othersin does one not analysis, exceedbut 0.70in ). all The others found does Asnot contents exceed in0.70 pyrargyrite ). The (solid found solution As contents with proustite) in pyrargyrite are very (solid low (up solution to 0.02 with apfu, i.e., proustite) 0.21 ), are very similar low to(up Asto contents 0.02 apfu, in all i.e., primary 0.21 ), sulfosalts similar of to theas hypogene contents mineralization all primary in Kutná sulfosalts Hora. of the hypogene mineralization in Kutná Hora. (a) (b) Py Prg Nau Ste Py Ste Py 20 m 10 m Figure 14. (a) An inclusion in pyrite (Py) of red ore (ii): stephanite (Ste), which is a prevailing mineral in Figure the inclusion 14. (a) An replaces inclusion pyrargyrite in pyrite (Py) (Prg). of red Remnants ore (ii): of stephanite original galena (Ste), which (white is spots) a prevailing whichmineral was later replaced in the inclusion by pyrargyrite replaces are pyrargyrite visible at(prg). the bottom Remnants part oforiginal the grain. galena (b) euhedral (white spots) crystal which in pyrite was later (Py) of red replaced ore (ii) by formed pyrargyrite by two are Ag-rich visible at mineral the bottom phases: part naumannite of the grain. (Nau) (b) euhedral is replaced crystal by stephanite in pyrite (Py) (Ste). Both back-scattered electron (BSE) images. Table 13. EPMA data for pyrargyrite. apfu Σ7 Atoms Ag Pb Cd Sb As Se S Total Ag Pb Cd Sb As Se S 2329 59.10 0.00 0.00 22.77 0.00 0.00 17.51 99.38 2.99 0.00 0.00 1.02 0.00 0.00 2.98 2471 59.38 0.07 0.08 22.95 0.00 0.00 18.13 100.60 2.95 0.00 0.00 1.01 0.00 0.00 3.03 2522 60.14 0.16 0.12 22.23 0.00 0.11 17.90 100.66 3.00 0.00 0.01 0.98 0.00 0.01 3.00 2528 61.11 0.00 0.00 21.94 0.00 0.15 17.63 100.83 3.02 0.00 0.00 0.96 0.00 0.01 2.93 2622 59.22 0.06 0.10 22.67 0.21 0.64 16.70 99.60 3.02 0.00 0.00 1.03 0.02 0.04 2.87 2729 61.69 0.00 0.00 21.74 0.00 0.69 17.53 101.65 3.06 0.00 0.00 0.96 0.00 0.05 2.93 are ordered according to increasing Se content. 4.4.3. Pyrostilpnite, Ag 3 SbS 3 Orange to bright red leaflets and coatings of pyrostilpnite on fractures of quartz gangue were described by Vepřek [53]. Later, Mrázek and Zeman [17] found orange-red elongated transparent crystalas up to 4 mm in length with intensive lustre in cavities of quartz gangue from the Vein I and Vein A (ore (iii)), determined by X-ray diffraction. In backscatter electron images, pyrostilpnite was not distinguished from its isochemical dimorph, pyrargyrite. However, orange crystals of pyrostilpnite under veinlets of pyragyrite were observed in optical microscope. 4.4.4. Stephanite, Ag 5 SbS 4 Stephanite occurs in red ore (ii) from the Vein B as rare anhedral grains up to 20 µm in size in fractures of miargyrite or as inclusions in miargyrite (Figure 2e), accompanied by exsolutions of pyrargyrite, itself being replaced by acanthite. It belongs to later minerals in the studied association.

Minerals 2019, 9, 430 22 of 47 It also occurs among drop-shaped inclusions in pyrite of red ore (ii), often rich in selenium (as much as 9.8 of Se) (Figure 14a,b and Figure 20b) or veinlets in miargyrite of red ore (ii) (Figure 24a). The chemical composition of stephanite and the corresponding chemical formulae are given in Table 14. One grain of stephanite is characteristic of a very high Se content of as much as 1.11 apfu (9.84, not included in Table 14 due to a lower total). Thus, stephanite together with miargyrite is the mineral with the highest determined range of the SeS 1 substitution among Ag-Sb-S mineral phases (Figure 13b). The selenium analogue of stephanite the mineral selenostephanite was described from two Russian deposits Rudnaya Sopka, Chukotka [54] and Julietta, Magadan region [55] and requires 17.3 or more of Se. Table 14. EPMA data for stephanite. apfu Σ10 Atoms Ag Cd Sb As Se S Total Ag Cd Sb As Se S 2343 68.62 0.15 16.64 0.13 0.00 16.03 101.57 4.98 0.01 1.07 0.01 0.00 3.91 2524 67.43 0.22 14.31 0.00 0.00 15.66 97.63 5.06 0.02 0.95 0.00 0.00 3.95 2525 67.76 0.13 15.00 0.02 0.00 16.18 99.10 4.99 0.01 0.98 0.00 0.00 4.01 Minerals 2019, 27559, x FOR 68.74 PEER REVIEW 0.00 14.07 0.00 0.00 15.64 98.45 5.13 0.00 0.93 0.00 0.00 223.92 of 45 2732 69.39 0.00 13.88 0.00 1.18 15.37 99.81 5.13 0.00 0.91 0.00 0.12 3.82 red ore 2747 (ii) (Figure 66.97 15a,b). 0.00 Polybasite 14.43 0.03 is in a 1.70 close 14.31 contact 97.44 with Se-rich 5.14 acanthite 0.00 0.98and 0.00both 0.18 minerals 3.69 replace galena. Associated minerals areforming ordered according inclusions to increasing pyrite Sebut content. not in a direct contact with polybasite include argyrodite, pyrargyrite, aguilarite, clausthalite and naumannite. Polybasite differs in minor but essential Cu content from chemically similar stephanite and also 4.4.5. by a different Polybasite, (Ag[Ag + Cu)/(Sb 9 CuS 4 ] [(Ag,Cu) + As) ratio. 6 (Sb,As) Copper 2 S 7 ] contents of only 0.22 0.44 apfu are lower than for minerals of polybasite group in the literature [56]; low contents of copper are characteristic Polybasite was found in four grains of two samples (8 point analyses) as very rare euhedral especially of selenium-containing members of this group [57]. Determined contents of Se in the table-like crystals 40 µm in length and 10 µm in width, cutting across galena inclusions in pyrite of red range 0.07 0.76 apfu (Figure 13b) in samples from Padua mine are lower than the minimal limit (>1 ore (ii) (Figure 15a,b). Polybasite is in a close contact with Se-rich acanthite and both minerals replace Se apfu) for selenopolybasite [57]. The content of the pearceite component in studied sample is low galena. and does Associated not exceed minerals 0.17 apfu forming As (0.55 ). inclusions The chemical in pyrite analyses but not of in polybasite a direct contact and corresponding with polybasite include empirical argyrodite, formulae pyrargyrite, are given in Table aguilarite, 15. clausthalite and naumannite. (a) (b) Aca Py Py Plb Plb Aca Py 30 m 20 m Figure 15. (a) Euhedral tabular crystal of polybasite (Plb) associated with Se-rich acanthite (Aca). Both Figure minerals 15. (a) Euhedral replace galena tabular (). crystal (b) of euhedral polybasite tabular (Plb) crystal associated of polybasite with Se-rich (Plb) acanthite growing (Aca). across galena, Both minerals which occurs replace as galena anhedral (). inclusions (b) euhedral uptabular to several crystal tensof of polybasite µm in pyrite (Plb)(Py) growing of red across ore (ii). Both galena, back-scattered which occurs electron as anhedral (BSE) inclusions images. up to several tens of μm in pyrite (Py) of red ore (ii). Both back-scattered electron (BSE) images. Polybasite differs in minor but essential Cu content from chemically similar stephanite and also by a different (Ag + Cu)/(Sb Table + As) 15. EPMA ratio. data Copper for polybasite. contents of only 0.22 0.44 apfu are lower than for minerals of polybasite group in the literature [56]; low contents apfu Ʃ29 ofatoms copper are characteristic especiallyag of selenium-containing Cu Pb Fe Cd Sb members As Se of this S group Total [57]. Ag Determined Cu Pb Fe contents Cd Sb ofas Se inse the range S 2589 71.20 0.61 0.51 0.30 0.13 10.72 0.04 0.95 14.97 99.43 15.36 0.22 0.06 0.13 0.03 2.05 0.01 0.28 10.87 2587 71.45 0.69 0.74 0.54 0.17 11.85 0.03 1.01 15.96 102.43 14.82 0.24 0.08 0.22 0.03 2.18 0.01 0.29 11.14 2595 70.62 1.11 0.08 0.72 0.14 9.67 0.55 2.61 14.81 100.31 14.97 0.40 0.01 0.30 0.03 1.82 0.17 0.76 10.56 4.5. Minerals of the Tetrahedrite Series are ordered according to increasing Se content.

Minerals 2019, 9, 430 23 of 47 0.07 0.76 apfu (Figure 13b) in samples from Padua mine are lower than the minimal limit (>1 Se apfu) for selenopolybasite [57]. The content of the pearceite component in studied sample is low and does not exceed 0.17 apfu As (0.55 ). The chemical analyses of polybasite and corresponding empirical formulae are given in Table 15. 4.5. Minerals of the Tetrahedrite Series Freibergite, Ag 6 [Cu 4 Fe 2 ]Sb 4 S 13 x Freibergite, together with miargyrite, is the most abundant silver mineral observed in the studied material (193 analyses). Freibergite occurs as crystals several mm in size in cavities of quartz kutnohorite gangue (red ore (ii)) or in cavities of milky white quartz (ore (iii)) or grain aggregates several cm in size associated with miargyrite and pyrargyrite (ores (ii) and (iii)). In polished sections, it was frequently found also in black ore (i), and it forms anhedral grains up to 300 µm in size. The grains are often zonal, growth zones differ by silver content, negatively correlated with the copper content. Freibergite grows together intimately with diaphorite and freieslebenite, usually being replaced by miargyrite. An example of freibergite in black ore (i) is shown in Figure 2c; freibergite in red ore (ii) is shown in Figure 16a,b; and ore (iii) is shown in Figure 2f. The status of Ag-rich members of tetrahedrite group (freibergite, argentotennantite) and especially their boundaries with tetrahedrite and tennantite, is still being investigated [44]. Some authors have proposed a minimum content for freibergite of 4 apfu Ag [44,58], and a condition of Ag > Cu for argentotennantite (about 5 apfu Ag) [59]. On the basis of the results of crystal structure studies [58,60] and analyses of natural samples [61,62], Ag preferentially occupies the triangular A position with total content 6 apfu, and according to the present rules of mineralogical nomenclature [31], the boundary would be 3 apfu Ag [62]. Two groups of compositions were identified. The majority of analyses (Table 16) represent typical freibergite with more than 4 apfu of Ag. Its chemical composition is fairly monotonous with regard to Fe/Zn and Sb/As ratios. Iron is always dominant, and As is not present, as is the case with all sulfosalts in hypogene mineralization in Kutná Hora. Zonality phenomena are visible in some grains quite profoundly, however, differing only moderately in terms of Ag/Cu ratio. Ag contents were determined from 3.99 apfu (23.33 ) to 7.25 apfu (38.61 ) in freibergite, indicating that the placement of Ag not only in the A position (up to 6 apfu), but also to a limited degree in the B position (up to 1.25 apfu) takes place. Freibergite with as much as 46.4 of Ag (8.93 apfu) was described from the Rejzské pásmo Lode in the Kutná Hora ore district [18]. This phase corresponds to the newly approved mineral rozhdestvenskayaite [63]. Ag and Cu contents show an excellent negative correlation (Figure 17a), which is in agreement with published results (e.g., [35,64,65]). In the case of freibergite below 6 apfu Ag, the rest of the A position is filled with copper. The B position, in addition to Ag contents (up to 0.40 apfu), is occupied by dominant Cu. In the C position, Fe (1.09 2.02 apfu) prevails over Zn (0.03 0.98 apfu), which is typical of freibergite (Figure 17b). Determined Ag/Cu ratios show no apparent correlation with Fe/Zn ratios. In the X position, the dominant Sb is in a part of analyses accompanied by negligible As, not exceeding 0.09 apfu (0.36 ). The second group of analyses corresponds to members at the boundary between freibergite and Ag-rich tetrahedrite. This member is very rare and was found only in one sample of black ore (i) as anhedral grains associated with galena, freieslebenite, diaphorite, owyheeite and Ag-excess fizélyite. Ag content varies from 17.41 to 18.48, corresponding to 2.93 to 3.15 apfu Ag, which is appreciably less than a typical common member of the tetrahedrite series, which is freibergite on all lodes of the Kutná Hore ore district. The chemistry is similar to freibergite in the respect that iron prevails over zinc, no arsenic substitutes for antimony (Table 17), and the substitution of Se for S is non-existent, although surrounding minerals contain as much as 1.1 of Se

Minerals 2019, 9, 430 24 of 47 Table 15. EPMA data for polybasite. apfu Σ29 Atoms Ag Cu Pb Fe Cd Sb As Se S Total Ag Cu Pb Fe Cd Sb As Se S 2589 71.20 0.61 0.51 0.30 0.13 10.72 0.04 0.95 14.97 99.43 15.36 0.22 0.06 0.13 0.03 2.05 0.01 0.28 10.87 2587 71.45 0.69 0.74 0.54 0.17 11.85 0.03 1.01 15.96 102.43 14.82 0.24 0.08 0.22 0.03 2.18 0.01 0.29 11.14 2595 70.62 1.11 0.08 0.72 0.14 9.67 0.55 2.61 14.81 100.31 14.97 0.40 0.01 0.30 0.03 1.82 0.17 0.76 10.56 are ordered according to increasing Se content. Table 16. EPMA data for freibergite. apfu Σ29 atoms Ag Cu Fe Zn Sb As Se S Total Ag Cu Fe Zn Sb As Se S Ag/A Cu/B 2419 23.33 20.84 4.72 1.64 26.83 0.01 0.00 22.34 99.71 3.99 6.05 1.56 0.46 4.07 0.00 0.00 12.85 3.99 4.04 2547 26.62 18.16 5.07 1.64 26.72 0.03 0.13 22.68 101.04 4.54 5.25 1.67 0.46 4.03 0.01 0.03 13.00 4.54 3.79 2548 27.49 17.76 5.15 1.90 26.65 0.08 0.12 22.50 101.66 4.68 5.13 1.69 0.53 4.02 0.02 0.03 12.88 4.68 3.81 2549 27.83 17.54 4.95 1.72 26.74 0.00 0.13 22.42 101.32 4.76 5.10 1.64 0.49 4.06 0.01 0.03 12.91 4.76 3.86 2246 28.78 16.57 5.30 0.97 26.48 0.00 0.00 21.46 99.56 5.07 4.96 1.80 0.28 4.14 0.00 0.00 12.73 5.07 4.03 812 29.59 14.64 5.27 1.00 26.38 0.15 0.00 21.58 98.61 5.27 4.43 1.81 0.29 4.16 0.04 0.00 12.93 5.27 3.70 63 31.22 15.18 3.41 3.16 25.69 0.19 0.00 21.09 99.94 5.56 4.59 1.17 0.93 4.05 0.05 0.00 12.63 5.56 4.15 811 32.11 13.60 4.97 1.12 26.29 0.11 0.00 21.45 99.66 5.73 4.12 1.72 0.33 4.16 0.03 0.00 12.88 5.73 3.86 67 33.24 14.09 3.48 2.95 25.61 0.22 0.00 21.06 100.65 5.92 4.26 1.20 0.87 4.04 0.06 0.00 12.62 5.92 4.18 1461 33.55 13.78 5.01 1.07 25.59 0.11 0.00 20.91 100.01 6.02 4.19 1.74 0.32 4.07 0.03 0.00 12.62 6.00 4.19 42 33.87 13.64 3.56 2.63 25.63 0.21 0.00 20.52 100.06 6.12 4.19 1.24 0.78 4.11 0.05 0.00 12.48 6.00 4.19 36 34.60 13.45 3.75 2.30 25.69 0.23 0.00 20.65 100.67 6.22 4.11 1.30 0.68 4.09 0.06 0.00 12.50 6.00 4.11 2142 34.80 13.03 5.58 0.11 26.15 0.00 0.00 20.44 100.11 6.31 4.01 1.95 0.03 4.20 0.00 0.00 12.47 6.00 4.01 2140 36.99 12.32 5.40 0.09 24.60 0.00 0.00 19.67 99.07 6.85 3.87 1.93 0.03 4.03 0.00 0.00 12.25 6.00 3.87 1120 38.61 11.96 4.32 1.15 21.94 0.10 0.00 19.51 97.57 7.25 3.81 1.57 0.36 3.65 0.03 0.01 12.32 6.00 3.81 Ag/A apfu of silver in triangular coordination; Cu/B apfu f Cu 1+ in tetrahedral coordination; are ordered according to increasing Ag content.

authors have proposed a minimum content for freibergite of 4 apfu Ag [44,58], and a condition of Ag > Cu for argentotennantite (about 5 apfu Ag) [59]. On the basis of the results of crystal structure studies [58,60] and analyses of natural samples [61,62], Ag preferentially occupies the triangular A Minerals position 2019, with 9, 430 total content 6 apfu, and according to the present rules of mineralogical nomenclature 25 of 47 [31], the boundary would be 3 apfu Ag [62]. (a) (b) Agd Frg 20 m Frg Clh 20 m Figure 16. (a) Fractured mass of porous sphalerite (dark grey) contains fissures filled by veinlets of freibergite Figure 16. (medium (a) Fractured grey) mass withof exsolutions porous sphalerite of Se-rich(dark miargyrite grey) contains (15 fissures of Se, light filled grey) by veinlets and members of of freibergite galena clausthalite (medium grey) solidwith solution exsolutions (white) of from Se-rich Gal70 Claus30 miargyrite (15 of ofse, Se) light to Claus78 Gal22 grey) and (20 members of of Se). galena clausthalite (b) freibergite (Frg) solid in quartz solution of red (white) ore (ii) from containing Gal70 Claus30 inclusions (15 of clausthalite of Se) to (Clh, Minerals Claus78 Gal22 2019, 9, x FOR (20 PEER REVIEW Se). (b) freibergite (Frg) in quartz of red ore (ii) containing inclusions of 24 of 45 21.5% of Se) or members of galena-clausthalite solid solution (, 14.2% of Se) and argyrodite (Agd, 9.8% clausthalite of Se). Both (Clh, back-scattered 21.5% of Se) or electron members (BSE) of galena-clausthalite images. solid solution (, 14.2% of Se) and argyrodite (Agd, 9.8% of Se). Both back-scattered electron (BSE) images. Two groups of compositions were identified. The majority of analyses (Table 16) represent 6.0 typical freibergite with more than 4 apfu of Ag. Its chemical composition is fairly monotonous with regard 5.5 to Fe/Zn and Sb/As ratios. Iron is always dominant, and As is not present, as is the case with all sulfosalts in hypogene mineralization in Kutná Hora. Zonality phenomena are visible in some 5.0 grains quite profoundly, however, differing only moderately in terms of Ag/Cu ratio. Ag contents were 4.5 determined from 3.99 apfu (23.33 ) to 7.25 apfu (38.61 ) in freibergite, indicating that the 4.0placement of Ag not only in the A position (up to 6 apfu), but also to a limited degree in the B position (up to 1.25 apfu) takes place. Freibergite with as much as 46.4 of Ag (8.93 apfu) was 3.5 described from the Rejzské pásmo Lode in the Kutná Hora ore district [18]. This phase corresponds 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 to the newly approved mineral rozhdestvenskayaite [63]. Ag and Cu contents show an excellent Ag ( apfu) negative correlation (Figure 17a), which is in agreement with published results (e.g., [35,64,65]). In the case Figure of freibergite 17. (a) Graph below of of Ag 6 apfu vs. Cu Ag, (apfu) the rest for freibergite; of the A position (b) graph is filled of of Fe vs. with Zn copper. (apfu) for The freibergite. B position, in addition to Ag contents (up to 0.40 apfu), is occupied by dominant Cu. In the C position, Fe (1.09 2.02 apfu) The second prevails group over of Zn analyses (0.03 0.98 corresponds apfu), which to is members typical of at freibergite the boundary (Figure between 17b). Determined freibergite and Table 17. EPMA data for Ag-rich tetrahedrite/freibergite. Ag-rich Ag/Cu ratios tetrahedrite. show no This apparent member correlation is very with rare Fe/Zn and was ratios. found In the only X position, in one sample the dominant of black Sb ore is in (i) as anhedral a part of analyses grains associated accompanied with by galena, negligible freieslebenite, As, not exceeding diaphorite, 0.09 apfu owyheeite apfu (0.36 Σ29). atoms and Ag-excess fizélyite. Ag content Ag varies Cufrom Fe17.41 Zn to 18.48 Sb, S Total corresponding Ag Cu to Fe 2.93 Zn to Sb 3.15 apfu S Ag, Ag/Awhich Cu/B is appreciably less than a typical common member of the tetrahedrite series, which is freibergite on all 2047 17.41 24.78 5.44 1.05 27.43 22.57 98.68 2.93 7.09 1.77 0.29 4.10 12.80 2.93 4.02 lodes 2045of the 17.84 Kutná 24.41 Hore 5.50 ore district. 1.08 27.64 The 22.65 chemistry 99.12 is 3.00 similar 6.97to 1.78 freibergite 0.30 4.12 in the 12.81respect 3.00 that 3.97 iron prevails 2046 over 18.48 zinc, 23.81 no arsenic 5.35 1.08 substitutes 27.40 22.24 for antimony 98.36 3.15 (Table 6.8917), 1.76 and 0.30 the substitution 4.13 12.74 3.15 of Se for 4.03 S is non-existent, Ag/A apfu of although silver in triangular surrounding coordination; minerals Cu/B apfu contain of Cuas 1+ in much tetrahedral as 1.1 coordination; of Se are ordered according to increasing Ag content. A very interesting thing in the chemistry of freibergite and tetrahedrite is the fact that selenium does not enter the structure of freibergite, even if the grains of freibergite occur in a Se-rich environment, A very interesting which was thing documented in the chemistry both in of black freibergite ore (i) andred tetrahedrite ore (ii). While is theall fact other thatassociated selenium does sulfosalts not enter take the in structure selenium of more freibergite, or less eagerly, even if the freibergite grains of remains freibergite Se-free. occur in a Se-rich environment, which was documented both in black ore (i) and red ore (ii). While all other associated sulfosalts take in selenium more or less eagerly, freibergite Table 16. EPMA remains data Se-free. for freibergite. Cu ( apfu) 6.5 (a) apfu Ʃ29 atoms Ag Cu Fe Zn Sb As Se S Total Ag Cu Fe Zn Sb As Se S Ag/A Cu/B 2419 23.33 20.84 4.72 1.64 26.83 0.01 0.00 22.34 99.71 3.99 6.05 1.56 0.46 4.07 0.00 0.00 12.85 3.99 4.04 2547 26.62 18.16 5.07 1.64 26.72 0.03 0.13 22.68 101.04 4.54 5.25 1.67 0.46 4.03 0.01 0.03 13.00 4.54 3.79 2548 27.49 17.76 5.15 1.90 26.65 0.08 0.12 22.50 101.66 4.68 5.13 1.69 0.53 4.02 0.02 0.03 12.88 4.68 3.81 2549 27.83 17.54 4.95 1.72 26.74 0.00 0.13 22.42 101.32 4.76 5.10 1.64 0.49 4.06 0.01 0.03 12.91 4.76 3.86 2246 28.78 16.57 5.30 0.97 26.48 0.00 0.00 21.46 99.56 5.07 4.96 1.80 0.28 4.14 0.00 0.00 12.73 5.07 4.03 812 29.59 14.64 5.27 1.00 26.38 0.15 0.00 21.58 98.61 5.27 4.43 1.81 0.29 4.16 0.04 0.00 12.93 5.27 3.70 63 31.22 15.18 3.41 3.16 25.69 0.19 0.00 21.09 99.94 5.56 4.59 1.17 0.93 4.05 0.05 0.00 12.63 5.56 4.15 811 32.11 13.60 4.97 1.12 26.29 0.11 0.00 21.45 99.66 5.73 4.12 1.72 0.33 4.16 0.03 0.00 12.88 5.73 3.86 67 33.24 14.09 3.48 2.95 25.61 0.22 0.00 21.06 100.65 5.92 4.26 1.20 0.87 4.04 0.06 0.00 12.62 5.92 4.18 1461 33.55 13.78 5.01 1.07 25.59 0.11 0.00 20.91 100.01 6.02 4.19 1.74 0.32 4.07 0.03 0.00 12.62 6.00 4.19 (b)

Minerals 2019, 9, x FOR PEER REVIEW 25 of 45 4.6. Ag-S, Ag-Se-S and Ag-Se Phases Minerals 2019, 9, 430 26 of 47 4.6.1. Acanthite, Ag2S Acanthite occurs as anhedral grains, fillings of other silver minerals, or veinlets 50 μm wide and 4.6. several Ag-S, hundred Ag-Se-S μm and long, Ag-Se associated Phases with pyrargyrite, allargentum and native silver (Figure 18a) in quartz kutnohorite gangue of red ore (ii), where it originated from former argentite. It belongs to the 4.6.1. Acanthite, Ag 2 S latest minerals in the association. This acanthite shows no selenium content. The second mode of occurrence Acanthite of occurs acanthite as anhedral is drop-like grains, inclusions fillings of of up other to 30 silver μm minerals, pyrite of orred veinlets ore (ii), 50 which µm wide are and several characteristic hundred of µm increased long, associated Se content with pyrargyrite, a continual transition allargentum to aguilarite and nativeand silver naumannite (Figure 18a) in(figure quartz kutnohorite 18b d). Occasionally, gangueinhomogeneous of red ore (ii), where grains it with originated oscillating fromse former content argentite. occur. Grains It belongs of toacanthite the latest richest minerals selenium in the association. (with composition Thisclose acanthite to aguilarite) shows no are selenium usually under content. 10 x 10 The μm. second In mode the third of occurrence mode of occurrence of acanthite inclusions is drop-like of galena inclusions pyrite ofare uppartially to 30 µmreplaced in pyrite by of acanthite, red ore (ii), which which has a significant selenium content. It is fairly frequent in red ore (ii), associated (but not in direct are characteristic of increased Se content with a continual transition to aguilarite and naumannite contact) with naumannite, clausthalite, argyrodite and aguilarite. (Figure 18b d). Occasionally, inhomogeneous grains with oscillating Se content occur. Grains of Chemical composition of acanthite and corresponding chemical formulae are given in Table 18. acanthite richest in selenium (with composition close to aguilarite) are usually under 10 x 10 µm. In the Increased selenium contents are characteristic of the studied acanthite. In most cases, these are up to third mode of occurrence inclusions of galena in pyrite are partially replaced by acanthite, which has a 0.13 apfu, some very small grains have as much as 0.30 apfu (8.83 ) (Figure 19). With regard to significant the small size selenium of grains, content. measured It is fairly minor frequent contents of in Cu, red Pb, ore Fe, (ii), Zn associated and Sb in (but some not analytical in direct points contact) with are naumannite, probably influenced clausthalite, by surrounding argyroditephases. and aguilarite. (a) Prg Slv* Slv Aca (b) Py Agu Slv* Ala Ala 200 m Ala Prg Slv* Prg Ala Aca Aca* Aca Py 10 m (c) (d) Aca Py 10 m Acs 30 m Figure 18. (a) Mass and veinlets of allargentum (Ala) and Sb-rich silver (Slv*); veinlets thicken up to form Figure grains 18. (a) of pure Mass Sb-free and veinlets silver of (Slv). allargentum Pyragyrite (Ala)(Prg) and Sb-rich forms euhedral silver (Slv*); masses veinlets andthicken acanthite up to (Aca) forms form veinlets grains of and pure fillings Sb-free around silver allargentum. (Slv). Pyragyrite Residues (Prg) forms of original euhedral galena masses () and areacanthite visible at(aca) the right side forms of the veinlets grain, and the fillings mineral around is replaced allargentum. by acanthite. Residues (b) of aguilarite original galena (Agu, () 18 are visible of Se) at replacing the right side of the grain, the mineral is replaced by acanthite. (b) aguilarite (Agu, 18 of Se) galena () in one of plentiful galena inclusions in pyrite of red ore (ii). Some of the inclusions are replacing galena () in one of plentiful galena inclusions in pyrite of red ore (ii). Some of the fully replaced by Se-rich acanthite (Aca*, 4 of Se), which forms a nearly continuous solid solution from acanthite with no Se (Aca) through Se-rich acanthite to aguilarite and naumannite. (c) diversity of inclusions in pyrite of red ore (ii); the larger inclusion shows the replacement of galena (white) by acanthite (dark grey). The smaller inclusion below is argyrodite. d) large inclusion of Se-rich acanthite (Aca), inclusion of galena () and an inclusion of an unnamed Ag-Cu-S phase (Acs) in pyrite (Py) of red ore (ii).

Aguilarite was confirmed in one sample as a small anhedral grain 6 4 μm in a galena inclusion (25 μm across) in pyrite of red ore (ii) (Figure 18b); aguilarite replaces galena. The galena inclusion was surrounded by (but not in direct contact with) smaller inclusions or semi-euhedral grains of Minerals 2019, 9, 430 27 of 47 Chemical composition of acanthite and corresponding chemical formulae are given in Table 18. Increased selenium contents are characteristic of the studied acanthite. In most cases, these are up to 0.13 apfu, some very small grains have as much as 0.30 apfu (8.83 ) (Figure 19). With regard to the small size of grains, measured minor contents of Cu, Pb, Fe, Zn and Sb in some analytical points are probably influenced by surrounding phases. Table 18. EPMA data for acanthite. apfu Σ3 Atoms Minerals 2019, Ag 9, x Cu FOR PEER Pb REVIEW Fe Cd Se S Cl Total Ag Cu Pb Fe Cd Se S 26 Clof 45 2814 86.85 0.13 0.00 0.00 0.00 0.00 12.16 0.00 99.39 2.03 0.01 0.00 0.00 0.00 0.00 0.96 0.01 2647 inclusions 87.50 0.00 are fully 0.05 0.42 replaced 0.17 by 1.03 Se-rich 11.77 acanthite 0.00 100.93 (Aca*, 2.03 4 0.00 of 0.00 Se), 0.02 which 0.00forms 0.03 a 0.92 nearly 0.00 2646 85.66 0.00 0.09 0.47 0.22 1.21 11.06 0.00 98.71 2.04 0.00 0.00 0.02 0.00 0.04 0.89 0.00 continuous solid solution from acanthite with no Se (Aca) through Se-rich acanthite to aguilarite and 2719 84.15 0.09 1.03 0.04 1.42 11.28 0.56 98.70 1.97 0.00 0.05 0.00 0.05 0.89 0.04 2623 naumannite. 83.18 0.00(c) 0.18 diversity 0.03 0.16 of inclusions 3.64 12.36 in pyrite 0.00 99.82 of red 1.91 ore (ii); 0.00the 0.00 larger 0.00inclusion 0.11shows 0.96 the 0.00 2579 replacement 83.95 0.00of galena 0.00 1.62 (white) 0.23by 4.01 acanthite 12.45 (dark 0.00grey). 102.31The 1.87 smaller 0.00inclusion 0.07 below 0.00is argyrodite. 0.12 0.93 d) 0.00 2596 large 84.13 inclusion 0.05 of 0.05Se-rich 0.64 acanthite 0.18 3.98(Aca), 11.65inclusion 0.00 100.67 of galena 1.94() 0.00and 0.00 an inclusion 0.03 0.00of 0.13 an unnamed 0.90 0.00 2594 85.15 0.00 0.00 0.50 0.17 4.29 11.55 0.00 101.68 1.95 0.00 0.00 0.02 0.00 0.13 0.89 0.00 Ag-Cu-S phase (Acs) in pyrite (Py) of red ore (ii). 2601 79.66 0.33 0.77 0.05 0.06 8.83 8.29 0.00 98.27 1.97 0.01 0.01 0.00 0.00 0.30 0.69 0.00 Increased Fe and Pb contents are caused by surrounding galena or pyrite. are ordered according to increasing Se content. 40 30 acanthite aguilarite naumannite S (at. %) 20 10 0 4.6.2. Aguilarite, Ag 4 SeS Figure Figure 19. 19. Graph Graph Se vs. Se vs. S (at.%) S (at.%) for for acanthite, aguilarite and and naumannite. Table 18. EPMA data for acanthite. Aguilarite was confirmed in one sample as a small anhedral grain 6 apfu 4 µmʃ3 in Atoms a galena inclusion (25 µm across) Ag in pyrite Cu of Pb redfe ore Cd (ii) (Figure Se 18b); S Cl aguilarite Total replaces Ag Cu galena. Pb The Fe galena Cd Se inclusion S Cl was surrounded 2814 86.85 by 0.13 (but0.00 not in 0.00 direct 0.00 contact 0.00 12.16 with) 0.00 smaller 99.39 inclusions or 2.03 0.01 0.00 semi-euhedral 0.00 0.00 0.00 grains of 0.96 0.01 acanthite 2647 with 87.50 variable 0.00 0.05 selenium 0.42 0.17 content 1.03 (from 11.77 zero 0.00 to100.93 4 ). 2.03 Plentiful 0.00 0.00 inclusions 0.02 0.00 in0.03 pyrite 0.92 of0.00 2646 85.66 0.00 0.09 0.47 0.22 1.21 11.06 0.00 98.71 2.04 0.00 0.00 0.02 0.00 0.04 0.89 0.00 this sample are formed apart from predominant galena and occasional acanthite by argyrodite, 2719 84.15 0.00 0.09 1.03 0.04 1.42 11.28 0.56 98.70 1.97 0.00 0.00 0.05 0.00 0.05 0.89 0.04 freibergite, 2623 (Ge,Se)-rich 83.18 0.00 0.18 acanthite, 0.03 0.16 clausthalite, 3.64 12.36 naumannite, 0.00 99.82 polybasite, 1.91 0.00 pyrargyrite 0.00 0.00 0.00 and0.11 unnamed 0.96 0.00 Ag-Cu-S 2579 phases. 83.95 0.00 0.00 1.62 0.23 4.01 12.45 0.00 102.31 1.87 0.00 0.00 0.07 0.00 0.12 0.93 0.00 2596 84.13 0.05 0.05 0.64 0.18 3.98 11.65 0.00 100.67 1.94 0.00 0.00 0.03 0.00 0.13 0.90 0.00 2594 85.15 0.00 0.00 0.50 0.17 4.29 11.55 0.00 101.68 1.95 0.00 0.00 0.02 0.00 0.13 0.89 0.00 2601 79.66 0.33 0.77 0.05 0.06 8.83 8.29 0.00 98.27 1.97 0.01 0.01 0.00 0.00 0.30 0.69 0.00 Increased Fe and Pb contents are caused by surrounding galena or pyrite. are ordered according to increasing Se content. 4.6.2. Aguilarite, Ag4SeS 0 5 10 15 20 25 30 35 Se (at. %)

Minerals 2019, 9, 430 28 of 47 The chemical composition of aguilarite exhibitss contents of Se in the range of 1.22 1.28 apfu (Table 19); with regard to the small size of grains, the measured minor contents of Pb and Fe are likely to be caused by surrounding phases. Aguilarite was defined by Bindi and Pingitore [66] as a member of the monoclinic solid solution acanthite aguilarite with Se>S (more than 16.67 at.% Se), and at the same time, with Se contents below ca. 1.4 apfu (23.33 at.%), which represents a boundary for an orthorhombic S-rich naumannite (Figure 19). Table 19. EPMA data for aguilarite. apfu Σ6 Atoms Ag Pb Fe Cd Se S Total Ag Pb Fe Cd Se S 2577 74.02 1.64 1.84 0.20 17.59 4.65 99.94 3.75 0.04 0.18 0.01 1.22 0.79 2578 75.50 0.16 1.77 0.19 18.16 3.62 99.41 3.90 0.00 0.18 0.01 1.28 0.63 Elevated levels of Pb and Fe are caused by surrounding galena or pyrite. The nomenclature of mineral phases along the Ag 2 S Ag 2 Se join was published by Bindi and Pingitore [66]. They suggest that two distinct solid solution series could exist: monoclinic acanthite-type series including aguilarite in the range Ag 2 S Ag 2 S 0.4 Se 0.6, and an orthorhombic naumannite-type series between Ag 2 S 0.3 Se 0.7 Ag 2 Se. The status of members with Se contents in the range 0.60 0.70 (or 1.2 1.4 for 6 apfu of aguilarite), which correspond to two-phase (monoclinic and orthorhombic) field as was described by Pingitore et al. [67] or Pal yanova et al. [68] is still under debate. According to Kullerud et al. [69], there are two possible explanations presence of metastable cubic high-temperature phase or mixtures of two submicroscopic phases formed during cooling of homogenous cubic phase below 80 C. Natural minerals with compositions related to this two-phase field have also been reported [68,69]. The described aguilarite in Table 19 shows Se contents within the above-mentioned range, i.e., between 1.22 and 1.28 apfu, corresponding to 0.61 and 0.64 apfu, if calculated to 3 apfu. However, it is impossible to decide whether a metastable phase or a mixture of two submicroscopic phases is present. 4.6.3. Naumannite, Ag 2 Se Naumannite was found in four grains of three samples (9 point analyses). The mode of occurrence is very similar to aguilarite, i.e., in drop-like inclusions in massive pyrite of red ore (ii). In the first sample, an inclusion of Se-rich miargyrite (8.7 wt% of Se) 100 µm across in pyrite contains an euhedral grain of naumannite 30 µm across and a semi-euhedral grain of clausthalite. Clausthalite and naumannite are not in direct contact and both minerals replace Se-rich miargyrite (Figure 20a). The second grain occurs in a 20 µm inclusion in pyrite formed by clausthalite, Se-rich stephanite (9.8 of Se) and naumannite. Clausthalite appears to be the earliest mineral, replaced by both stephanite and naumannite. In the third sample, an inclusion in pyrite 30 µm across is formed by Se-rich stephanite (9.1 of Se), which is replaced by naumannite. The shape of the inclusion is not drop-like, but rather euhedral, following the crystal shape of stephanite (Figure 14b). The fourth sample occurs in a galena inclusion of 140 µm in pyrite. An anhedral grain of naumannite 6 µm across replaces galena at one of its edges. Chemical composition of naumannite and corresponding chemical formulae are given in Table 20; the range of SSe 1 substitution in naumannite was determined to be 0.01 0.18 apfu (Figure 19). With regard to the small size of grains, minor measured contents of Pb and Fe insome analytical points are probably influenced by surrounding phases.

Minerals 2019, 9, 430 29 of 47 Minerals 2019, 9, x FOR PEER REVIEW 28 of 45 Nau (a) Ste (b) Agd Frg Py Py Clh Mia Sp 20 m Nau 20 m Figure 20. (a) Larger inclusion in pyrite of red ore (ii): clausthalite (Clh, 19.6% of Se) and naumannite (Nau, Figure 23.9 20. (a) Larger of Se) inclusion replace selenian in pyrite miargyrite of red ore (ii): (Mia, clausthalite 8.7 of (Clh, Se). 19.6% Smaller of Se) inclusion: and naumannite naumannite and (Nau, selenian 23.9 stephanite of Se) (Ste, replace 9.8 selenian of Se) miargyrite replace an(mia, intermediate 8.7 member of Se). of Smaller galena clausthalite inclusion: solid naumannite solution and (, selenian 13.9% stephanite of Se, 5.3% (Ste, of S). 9.8 (b) Se-rich of Se) argyrodite replace an (Agd, intermediate 4.9 member of Se) bordering of galena on freibergite clausthalite (Frg) solid insolution a galena (, () 13.9% inclusion of Se, in5.3% pyrite of S). of red (b) ore Se-rich (ii). argyrodite Argyrodite(Agd, and freibergite 4.9 of replace Se) galena, bordering bothon minerals freibergite are (Frg) rimmed in a bygalena pyrite () (Py). inclusion in pyrite of red ore (ii). Argyrodite and freibergite replace galena, both minerals are rimmed by pyrite (Py). Chemical composition of naumannite Table 20. EPMA and corresponding data for naumannite. chemical formulae are given in Table 20; the range of SSe-1 substitution in naumannite was determined to be 0.01 0.18 apfu (Figure 19). apfu Σ3 atoms With regard to the small size of grains, minor measured contents of Pb and Fe insome analytical points are probably Ag influenced Pb by Fesurrounding Cd Se phases. S Total Ag Pb Fe Cd Se S 2597 75.43 0.10 0.92 0.21 20.69 1.96 99.30 2.01 0.00 0.05 0.01 0.75 0.18 2696 74.20 0.00 1.06 Table 0.17 20. EPMA 23.94data 0.31 for naumannite. 99.66 2.02 0.00 0.06 0.00 0.89 0.03 2694 74.48 0.00 0.98 0.00 23.93 0.23 99.62 2.03 0.00 0.05 0.00 0.89 0.02 apfu Ʃ3 atoms 2698 74.10 0.00 0.66 0.05 23.74 0.20 98.76 2.04 0.00 0.04 0.00 0.89 0.02 2697 74.06 Ag Pb 0.00 Fe 0.56 Cd 0.05 Se 23.83 S 0.21Total 98.69Ag 2.05Pb 0.00Fe 0.03 Cd 0.00 Se 0.90S 0.02 2695 2597 75.43 73.86 0.10 0.00 0.92 0.59 0.21 0.0520.69 23.951.96 0.2299.30 98.662.01 2.03 0.00 0.00 0.050.03 0.010.00 0.750.90 0.18 0.02 2696 74.20 0.00 1.06 0.17 23.94 0.31 99.66 2.02 0.00 0.06 0.00 0.89 0.03 4.7. Ag-Ge-S 2694 and Ag-Cu-S 74.48 0.00 sulfides 0.98 0.00 23.93 0.23 99.62 2.03 0.00 0.05 0.00 0.89 0.02 2698 74.10 0.00 0.66 0.05 23.74 0.20 98.76 2.04 0.00 0.04 0.00 0.89 0.02 4.7.1. Argyrodite, 2697 Ag 74.06 8 GeS0.00 6 0.56 0.05 23.83 0.21 98.69 2.05 0.00 0.03 0.00 0.90 0.02 2695 73.86 0.00 0.59 0.05 23.95 0.22 98.66 2.03 0.00 0.03 0.00 0.90 0.02 Argyrodite was found in nine grains of three samples (16 point analyses). It occurs as individual anhedral grains up to 40 µm among bubble-shaped inclusions in pyrite of red ore (ii) (Figure 18c). 4.7. Ag-Ge-S and Ag-Cu-S sulfides It was also found in sphalerite as a 12 µm grain bordering on freibergite in a galena inclusion of 45 µm (Figure 4.7.1. Argyrodite, 20b). Argyrodite and freibergite replace galena and are rimmed by pyrite. The replacement Ag8GeS6 progresses from the clean-cut boundary with pyrite towards the centre of the galena inclusion, which is completely Argyrodite enclosed was in found sphalerite; in nine in sphalerite grains of three associated samples with (16 miargyrite point analyses). and pyrite It (Figure occurs as 12b); individual anhedral grains up to 40 μm among bubble-shaped inclusions in pyrite of red ore (ii) and as inclusions in freibergite with remnants of members of galena-clausthalite solid solution, (Figure 18c). It was also found in sphalerite as a 12 μm grain bordering on freibergite in a galena which are replaced by freibergite (Figure 16b). inclusion of 45 μm (Figure 20b). Argyrodite and freibergite replace galena and are rimmed by pyrite. Chemical analyses of argyrodite are complicated due to the small size of the grains; the measured The replacement progresses from the clean-cut boundary with pyrite towards the centre of the contents of Cu and Fe probably come from surrounding phases. Apart from major elements (Ag, Ge a galena inclusion, which is completely enclosed in sphalerite; in sphalerite associated with miargyrite S), significant contents of Se up to 0.69 apfu (4.93 ) were found. The chemical composition and pyrite (Figure 12b); and as inclusions in freibergite with remnants of members of and corresponding chemical formulae are given in Table 21. The discovery of germanium in the galena-clausthalite solid solution, which are replaced by freibergite (Figure 16b). geochemistry Chemical of analyses the Kutná of Hora argyrodite ore district are complicated shows another due similarity to the small with size the of Freiberg the grains; ore district, the which measured is the contents type locality of Cu for and argyrodite. Fe probably come from surrounding phases. Apart from major elements (Ag, Ge a S), significant contents of Se up to 0.69 apfu (4.93 ) were found. The chemical composition and corresponding chemical formulae are given in Table 21. The discovery of

Minerals 2019, 9, 430 30 of 47 Table 21. EPMA data for argyrodite. apfu Σ15 atoms Ag Cu Pb Fe Zn Ge Sb Se S Total Ag Cu Pb Fe Zn Ge Sb Se S 2614 78.19 0.00 0.11 1.84 0.00 5.66 0.13 0.10 17.72 103.84 7.80 0.01 0.01 0.35 0.00 0.838 0.01 0.01 5.94 2615 78.70 0.00 0.11 1.68 0.00 5.89 0.27 0.14 17.64 104.43 7.83 0.00 0.01 0.32 0.00 0.871 0.02 0.02 5.90 2616 73.91 0.00 1.11 1.40 0.00 6.95 0.60 0.70 17.05 101.81 7.57 0.00 0.06 0.28 0.00 1.06 0.05 0.10 5.87 2619 73.60 0.55 0.00 1.97 0.00 6.00 0.08 1.00 17.75 101.15 7.42 0.09 0.00 0.38 0.01 0.90 0.01 0.14 6.02 2707 72.59 0.54 0.25 2.31 0.00 5.53 0.00 1.03 18.04 100.63 7.31 0.09 0.01 0.45 0.01 0.83 0.00 0.14 6.12 2708 73.73 0.05 0.00 0.90 1.07 5.91 0.31 3.58 16.26 102.06 7.56 0.01 0.00 0.18 0.18 0.90 0.03 0.50 5.61 Elevated levels of Pb, Fe or Zn are caused by surrounding galena, pyrite or sphalerite. are ordered according to incereasing Se content.

Cu (at. %) S+Se (at. %) Ag Cu Pb Fe Zn Ge Sb Se S Total Ag Cu Pb Fe Zn Ge Sb Se S 2614 78.19 0.00 0.11 1.84 0.00 5.66 0.13 0.10 17.72 103.84 7.80 0.01 0.01 0.35 0.00 0.838 0.01 0.01 5.94 2615 78.70 0.00 0.11 1.68 0.00 5.89 0.27 0.14 17.64 104.43 7.83 0.00 0.01 0.32 0.00 0.871 0.02 0.02 5.90 2616 73.91 0.00 1.11 1.40 0.00 6.95 0.60 0.70 17.05 101.81 7.57 0.00 0.06 0.28 0.00 1.06 0.05 0.10 5.87 2619 73.60 0.55 0.00 1.97 0.00 6.00 0.08 1.00 17.75 101.15 7.42 0.09 0.00 0.38 0.01 0.90 0.01 0.14 6.02 2707 72.59 0.54 0.25 2.31 0.00 5.53 0.00 1.03 18.04 100.63 7.31 0.09 0.01 0.45 0.01 0.83 0.00 0.14 6.12 2708 73.73 0.05 0.00 0.90 1.07 5.91 0.31 3.58 16.26 102.06 7.56 0.01 0.00 0.18 0.18 0.90 0.03 0.50 5.61 Minerals 2019, 9, 430 31 of 47 Elevated levels of Pb, Fe or Zn are caused by surrounding galena, pyrite or sphalerite. are ordered according to incereasing Se content. 4.7.2. Ag-Cu-S Phases 4.7.2. Ag-Cu-S Phases Unnamed Ag-Cu-(S,Se) phases were found in five grains of three samples (23 point analyses) and Unnamed Ag-Cu-(S,Se) phases were found in five grains of three samples (23 point analyses) occur in a very similar way to argyrodite as individual inclusions in pyrite, not in contact with any and occur in a very similar way to argyrodite as individual inclusions in pyrite, not in contact with other mineral (Figures 18d and 21a). These phases were found as anhedral grains up to 50 30 µm any other mineral (Figures 18d and 21a). These phases were found as anhedral grains up to 50 30 among predominantly galena inclusions in pyrite in red ore (ii) (Figure 21b) and belong to the latest μm among predominantly galena inclusions in pyrite in red ore (ii) (Figure 21b) and belong to the minerals. Similar to selenides and argyrodite, these grains are enclosed in pyrite growth zones with latest minerals. Similar to selenides and argyrodite, these grains are enclosed in pyrite growth zones plentiful with plentiful bubble-shaped bubble-shaped inclusions. inclusions. (a) Sp (b) Py Acs 20 m 200 m Figure 21. (a) Oval inclusion of unnamed Ag-Cu-(S,Se) phase (Acs) in pyrite (Py) of red ore (ii). Figure (b) 21. bubble-shaped (a) Oval inclusion inclusions of unnamed in pyrite Ag-Cu-(S,Se) of red ore phase (ii). (Acs) Plentiful in pyrite small (Py) inclusions of red ore (ii). in pyrite (b) are bubble-shaped formed apart inclusions from predominant pyrite of galena red ore and(ii). occasional Plentiful acanthite by small inclusions argyrodite, in pyrite freibergite are (Ge,Se)-rich formed apart acanthite, from clausthalite, predominant naumannite, galena and polybasite, occasional pyrargyrite acanthite by and unnamed argyrodite, Ag-Cu-S freibergite phases. Both (Ge,Se)-rich back-scattered acanthite, electron clausthalite, (BSE) images. naumannite, polybasite, pyrargyrite and unnamed Ag-Cu-S phases. Both back-scattered electron (BSE) images. A common feature of all analyses (Table 22) is that the metal/sulphur ratio is between 1.36 and 1.74, whilea all common known Ag-Cu-S feature of minerals all analyses have (Table this ratio 22) is equal that the to 2. metal/sulphur Higher contents ratio of is S between + Se in1.36 the anionic and part 1.74, suggest while all a different known Ag-Cu-S structural minerals arrangement have this thanratio in known equal phases to 2. Higher and/or contents a possible of S involvement + Se the of Cu anionic 2+ cation. part The suggest Ag and a different Cu contents structural witharrangement a clear negative than correlation in known phases (Figureand/or 22a) were a possible observed. They involvement differ from of Cu known 2+ cation. phases The Ag in the and Ag-Cu-S contents system with with a clear respect negative to: a) correlation the Ag/Cu (Figure ratio, 22a) and b) higher were observed. contents of They Se in differ the from anionic known part phases (Figure in 22b); the Ag-Cu-S the contents system of minor with respect Se were to: determined a) the Ag/Cu to be ratio, and b) higher contents of Se in the anionic part (Figure 22b); the contents of minor Se were between 2 and 5 at.%. With regard to the rarity of Ag-Cu-S phases and to the minimal size of grains determined to be between 2 and 5 at.%. With regard to the rarity of Ag-Cu-S phases and to the which Minerals does 2019, not 9, x FOR rulepeer the influence REVIEW of surrounding phases (especially contents of Fe and Zn), it cannot 30 of 45 minimal size of grains which does not rule the influence of surrounding phases (especially contents be decided whether the measured points belong to new mineral phases. of Fe and Zn), it cannot be decided whether the measured points belong to new mineral phases. 35 30 25 20 15 (a) stromeyerite mckinstryite jalpaite Anthony of Padua ideal composition 44 42 40 38 (b) Anthony of Padua ideal composition 10 36 5 0 acanthite 34 acanthite jalpaite mckinstryite stromeyerite 30 35 40 45 50 55 60 65 70 Ag (at. %) 32 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Cu/Ag Figure 22. 22. (a) (a) Graph Graph Ag vs. Ag Cu vs. (at.%) Cu for (at.%) Ag-Cu-S for Ag-Cu-S mineral phases; mineral composition phases; composition range for mckinstryite range for are mckinstryite given from are [70]; given (b) from graph[70]; Cu/Ag (b) graph vs. S Cu/Ag + Se (at.%) vs. S for + Se Ag-Cu-S (at.%) for mineral; Ag-Cu-S composition mineral; composition range for mckinstryite range for mckinstryite are given from are given [70]. from [70]. Table 22. EPMA data for unnamed Ag-Cu-S phases. at.% Ag Cu Pb Fe Cd Zn Se S Total Ag Cu Pb Fe Cd Zn Se S 2653 78.57 3.64 0.00 0.67 0.09 0.00 2.17 13.85 98.99 57.88 4.55 0.01 0.95 0.06 0.00 2.18 34.33

Minerals 2019, 9, 430 32 of 47 Table 22. EPMA data for unnamed Ag-Cu-S phases. Ag Cu Pb Fe Cd Zn Se S Total Ag Cu Pb Fe Cd Zn Se S 2653 78.57 3.64 0.00 0.67 0.09 0.00 2.17 13.85 98.99 57.88 4.55 0.01 0.95 0.06 0.00 2.18 34.33 2670 69.06 3.79 0.00 3.50 0.00 0.53 4.51 16.29 97.69 47.92 4.47 0.00 4.70 0.00 0.60 4.28 38.03 2664 75.73 4.91 0.19 0.88 0.17 0.20 4.76 12.72 99.57 55.82 6.14 0.07 1.26 0.12 0.25 4.80 31.53 2669 73.92 5.37 0.13 1.37 0.00 0.43 4.10 14.01 99.32 53.07 6.54 0.05 1.90 0.00 0.51 4.02 33.84 2668 74.92 5.41 0.11 1.46 0.05 0.41 4.39 14.14 100.88 53.03 6.50 0.04 2.00 0.03 0.48 4.24 33.66 2654 76.60 6.10 0.16 0.68 0.12 0.00 1.82 14.94 100.41 54.23 7.33 0.06 0.93 0.08 0.02 1.76 35.58 2649 72.54 7.46 0.19 0.84 0.15 0.00 2.60 15.09 98.86 51.23 8.94 0.07 1.14 0.10 0.04 2.51 35.85 2648 70.46 8.47 0.10 0.74 0.13 0.00 2.24 15.92 98.06 49.22 10.05 0.04 1.00 0.08 0.00 2.14 37.41 2650 68.35 8.89 0.19 1.07 0.08 0.00 3.51 15.18 97.26 48.25 10.65 0.07 1.46 0.05 0.00 3.38 36.04 2651 67.79 9.64 0.08 1.16 0.12 0.00 2.87 15.69 97.36 47.29 11.42 0.03 1.57 0.08 0.05 2.73 36.82 2734 60.24 15.60 0.22 1.45 0.10 0.00 2.21 18.11 97.92 39.15 17.21 0.07 1.82 0.06 0.00 1.96 39.59 2736 57.30 15.64 0.00 2.09 0.00 0.00 2.17 18.08 95.28 37.71 17.47 0.00 2.66 0.00 0.00 1.95 40.03 Elevated levels of Pb, Fe or Zn are caused by surrounding galena, pyrite or sphalerite. are ordered according to increasing Cu content. at.%

Minerals 2019, 9, 430 33 of 47 4.8. Native Elements; Ag, Au Sulfides and Antimonides 4.8.1. Silver, Ag Native silver occurs as yellow-white metallic aggregates several mm in size in cavities of the kutnohorite-quartz gangue of Vein B (red ore (ii)), associated with other silver minerals, namely with miargyrite, pyrargyrite and freibergite, and also in ore (iii) associated with pyragyrite, miargyrite and diaphorite. Silver occurs in two varieties, which differ with regard to Sb content: hypogene (primary) Sb-rich silver (Table 23) and later (mobilized) pure Sb-free native silver (Table 24). Polished sections of Sb-free silver were found as grains up to 50 µm in veinlets of Sb-rich silver several hundreds µm long, which form rims of masses of allargentum (Figure 18a). This pure native silver contains only traces of Hg, As, Fe and Cl. The more abundant Sb-rich silver is associated with pyrargyrite, acanthite, allargentum and Sb-free silver. Contents of Sb in the range 0.01 0.03 apfu (1.3 3.1 ) are characteristic of this type of silver (Table 23, Figure 23). Table 23. EPMA data for Sb-rich silver. apfu Σ1 Atom Ag Au Sb As Cl Total Ag Au Sb As Cl 2825 98.45 0.00 1.32 0.07 0.10 99.94 0.98 0.00 0.01 0.00 0.00 2827 98.49 0.00 1.89 0.00 0.11 100.49 0.98 0.00 0.02 0.00 0.00 2824 98.40 0.00 1.99 0.12 0.11 100.62 0.98 0.00 0.02 0.00 0.00 2813 98.16 0.00 2.10 0.11 0.11 100.48 0.97 0.00 0.02 0.00 0.00 2829 98.09 0.00 2.61 0.12 0.10 100.92 0.97 0.00 0.02 0.00 0.00 2844 97.16 0.00 2.73 0.05 0.10 100.04 0.97 0.00 0.02 0.00 0.00 2830 97.66 0.13 2.77 0.09 0.12 100.77 0.97 0.00 0.02 0.00 0.00 2838 97.17 0.09 2.92 0.09 0.13 100.40 0.97 0.00 0.03 0.00 0.00 2848 97.07 0.00 2.91 0.00 0.10 100.08 0.97 0.00 0.03 0.00 0.00 2833 97.53 0.00 2.99 0.15 0.12 100.79 0.97 0.00 0.03 0.00 0.00 2839 97.73 0.00 3.11 0.09 0.10 101.03 0.97 0.00 0.03 0.00 0.00 are ordered according to increasing Sb content. Table 24. EPMA data for silver. apfu Σ1 atom Ag Au Hg As Te Cl Total Ag Au Hg As Te Cl 2865 101.59 0.00 0.10 0.16 0.11 0.13 102.09 0.99 0.00 0.00 0.00 0.00 0.00 2866 101.61 0.06 0.00 0.07 0.12 0.11 101.97 0.99 0.00 0.00 0.00 0.00 0.00 2867 101.62 0.00 0.00 0.09 0.12 0.11 101.94 0.99 0.00 0.00 0.00 0.00 0.00 2868 101.53 0.00 0.20 0.10 0.10 0.13 102.06 0.99 0.00 0.00 0.00 0.00 0.00 2828 100.47 0.08 0.00 0.11 0.00 0.10 100.76 0.99 0.00 0.00 0.00 0.00 0.00 Interestingly, no native silver whatsoever occurs in plentiful bubble-like inclusions in pyrite all are acanthite with the exception of Au-rich silver (electrum). 4.8.2. Au-rich Silver (Ag,Au) Au-rich silver (electrum) was found in 10 grains of four samples (23 point analyses) of red ore (ii), enclosed in miargyrite (8 grains up to 10 µm; Figure 24a) or sphalerite (2 grains up to 42 µm; Figure 24b). The phase richest in gold (and also the largest grain) was found as an anhedral grain of 42 x 25 µm enclosed in Fe-rich sphalerite; it contains 0.42 0.44 apfu Au (56 57 ) (Figure 24b). Contents of Au were determined to be within the range 0.17 0.35 apfu (28 48 ). Traces of Hg, Sb and Te (Table 25) were also identified; the minor contents of S determined are probably caused by surrounding phases.

Minerals 2019, 9, x FOR PEER REVIEW 31 of 45 Minerals 2019, 9, 430 34 of 47 Sb (at. %) 30 25 20 4.8.2. Au-rich 15 Silver (Ag,Au) Sb-rich silver allargentum Au-rich dyscrazite Minerals 2019, 9, x FOR PEER REVIEW 32 of 45 Au-rich 10 silver (electrum) was found in 10 grains of four samples (23 point analyses) of red ore (ii), enclosed in miargyrite (8 grains up to 10 μm; Figure 24a) or sphalerite (2 grains up to 42 μm; Figure 24b). The phase richest in gold (and also the largest grain) was found as an anhedral grain of 5 42 x 25 μm enclosed in Fe-rich sphalerite; it contains 0.42 0.44 apfu Au (56 57 ) (Figure 24b). Contents of Au were determined to be within the range 0.17 0.35 apfu (28 48 ). Traces of Hg, Sb 0 and Te (Table 25) were also identified; the minor contents of S determined are probably caused by surrounding phases. Members of the Au-Ag solid solution (electrum) have been identified in the past from three 70 75 80 85 90 95 100 lodes of Kutná Hora ore district on the basis of ore microscopy as allotriomorphic grains up 10 μm Ag+Au (at. %) enclosed in freibergite, pyrargyrite or miagyrite. Only one occurrence was analysed chemically by emission spectral analysis Figure [71]. 23. 23. Graph Ag Ag + + Au Au vs. vs. Sb Sb (at.%) for Ag-Sb minerals. (a) Interestingly, no native silver whatsoever (b) occurs in plentiful bubble-like inclusions in pyrite all are acanthite with the exception of Au-rich silver (electrum). Table 23. Mia EPMA data for Sb-rich silver. apfu Ʃ1 Atom Ag Au Sb As Cl Total Ag Au Sb As Frg Cl 2825 98.45 0.00 1.32 0.07 0.10 99.94 0.98 0.00 0.01 0.00 0.00 2827 98.49 0.00 1.89 0.00 0.11 100.49 0.98 0.00 0.02 0.00 0.00 Mia Sp 2824 98.40 Ste 0.00 1.99 0.12 0.11 100.62 0.98 0.00 0.02 0.00 0.00 2813 98.16 0.00 2.10 0.11 0.11 100.48 0.97 0.00 0.02 0.00 0.00 282920 m 98.09 0.00 2.61 0.12 0.10 100.92 20 m 0.97 0.00 0.02 0.00 0.00 2844 97.16 0.00 2.73 0.05 0.10 100.04 0.97 0.00 0.02 0.00 0.00 Figure 2830 24. (a) 97.66 Two grains 0.13 of Au-rich 2.77 silver 0.09 (white) 0.12 in miargyrite 100.77 (Mia) 0.97 show0.00 signs of 0.02 crystal0.00 shape. 0.00 Veinlets Figure 2838 24. in (a) miargyrite 97.17 Two grains are 0.09 of filled Au-rich 2.92 in by silver stephanite 0.09 (white) 0.13 in (Ste); miargyrite 100.40 (b) Au-rich (Mia) 0.97 show silver signs (white) 0.00 of crystal associated 0.03 shape. 0.00 with 0.00 freibergite Veinlets 2848 in (Frg) miargyrite 97.07 in sphalerite are 0.00 filled (Sp) 2.91 in ofby redstephanite 0.00 ore (ii). 0.10 This (Ste); (semi-euhedral) (b) 100.08 Au-rich silver 0.97 grain (white) is 0.00 theassociated largest 0.03 individual with 0.00 0.00 grain freibergite 2833 (40 mm (Frg) 97.53 across) in sphalerite and 0.00 also (Sp) a2.99 grain of red with 0.15 ore (ii). the This highest 0.12 (semi-euhedral) Au 100.79 content (56.0 0.97 grain, is the 0.00 largest i.e., 42.5 0.03 individual at.% 0.00 of Au). 0.00 Both grain 2839 back-scattered (40 mm 97.73 across) electron and 0.00 also (BSE) a 3.11 grain images. with 0.09 the highest 0.10 Au 101.03 content (56.0 0.97, 0.00 i.e., 42.50.03 at.% of Au). 0.00 0.00 Both back-scattered electron (BSE) are images. ordered according to increasing Sb content. Members of the Au-Ag solid solution (electrum) have been identified in the past from three lodes of Kutná Hora ore district on thetable basis25. EPMA data for Au-rich silver. Table of ore 24. microscopy EPMA data as for allotriomorphic silver. grains up 10 µm enclosed in freibergite, pyrargyrite or miagyrite. Only one occurrence was analysed at% chemically by emission spectral Ag Au Hg Sb Te S Total Ag Au apfu Hg Ʃ1 atom Sb Te S analysis [71]. 2686 39.80 Ag 56.50 Au 0.00 Hg 0.00 As 0.07 Te 0.12 Cl 96.49 Total 55.90 Ag 43.46 Au 0.00 Hg 0.00 As 0.08 Te 0.56 Cl 4.8.3. 2689 2865 Uytenbogaardtite 40.82 101.5956.41 0.00 Ag 0.000.10 0.000.16 0.120.110.08 0.1397.42 102.09 56.62 0.99 42.85 0.00 0.00 0.00 0.00 0.00 0.14 0.00 0.36 3 AuS 2 0.00 2692 40.71 56.36 0.00 0.09 0.10 97.26 56.52 42.85 0.00 0.00 0.10 0.46 2684 2866 40.73 101.6156.06 0.06 0.00 0.00 0.000.07 0.090.120.08 0.1196.95 101.97 56.76 0.99 42.79 0.00 0.00 0.00 0.00 0.00 0.10 0.00 0.35 0.00 Uytenbogaardtite was found as one semi-euhedrall grain 9 6 µm in massive miargyrite of red 2685 2867 40.95 101.6256.31 0.00 0.00 0.00 0.000.09 0.100.120.08 0.1197.44 101.94 56.71 0.99 42.71 0.00 0.00 0.00 0.00 0.00 0.12 0.00 0.38 0.00 ore (ii). The image in Figure 25a reveals that the grain contains minute inclusions of Au-rich silver 2683 2868 40.92 101.5355.84 0.00 0.00.200.000.10 0.060.10.08 0.1396.90 102.06 56.92 0.99 42.54 0.00 0.00 0.00 0.00 0.00 0.07 0.00 0.36 0.00 (white 2690 spots, one 41.15 larger 55.88 one0.00 is visible 0.00 at the 0.12 left0.12 edge 97.26 of the grain) 56.94 with 42.3451.00.00 0.02 of Au0.13 and 46.3 0.54 2828 100.47 0.08 0.00 0.11 0.00 0.10 100.76 0.99 0.00 0.00 0.00 0.00 0.00 of Ag 2691 (corresponding 41.41 55.53 to 35.70.00 at.% 0.00 Au), which 0.09 are 0.09 probably 97.12 responsible 57.34 42.11 for0.00 the lower 0.00 sulphur 0.10 0.41 content 2688 41.89 55.68 0.00 0.00 0.00 0.10 97.66 57.59 41.92 0.00 0.00 0.03 0.46 in the measured points of uytenbogaardtite. The top and right edge of the grain displays a hem 2687 41.86 55.59 0.00 0.00 0.12 0.09 97.66 57.58 41.87 0.00 0.00 0.14 0.41 resembling 2571 a 48.58 reaction47.84 product. 0.00 However, 0.29 0.11 the 0.07 hem is96.90 formed64.42 by uytenbogaardtite 34.74 0.00 0.34 with0.13 increased 0.33 Sb content, 2572 a possible 50.57 contamination 45.87 0.20 0.36 from surrounding 0.11 0.09 97.19 miargyrite. 66.10 32.83 0.14 0.41 0.13 0.39 2630 49.52 42.53 0.97 0.85 0.00 2.87 96.73 59.11 27.80 0.62 0.90 0.02 11.52 2627 56.48 39.40 0.52 0.83 0.15 0.76 98.14 69.06 26.38 0.34 0.90 0.16 3.13 2573 59.18 36.84 0.48 0.58 0.09 0.53 97.70 72.14 24.60 0.31 0.63 0.09 2.17 2574 59.43 36.62 0.00 0.74 0.10 0.57 97.46 72.35 24.41 0.00 0.80 0.11 2.33 2575 62.13 33.51 0.00 1.07 0.12 0.44 97.27 74.86 22.11 0.00 1.15 0.13 1.76 2749 61.73 32.85 0.00 1.20 0.00 0.69 96.48 73.96 21.56 0.00 1.28 0.00 2.77 2629 63.97 31.35 0.30 1.69 0.14 1.18 98.64 73.60 19.75 0.18 1.73 0.14 4.57

Minerals 2019, 9, 430 35 of 47 Table 25. EPMA data for Au-rich silver. Ag Au Hg Sb Te S Total Ag Au Hg Sb Te S Minerals 2019, 2686 9, x FOR PEER 39.80 REVIEW 56.50 0.00 0.00 0.07 0.12 96.49 55.90 43.46 0.00 0.00 0.08 33 of 45 0.56 2689 40.82 56.41 0.00 0.00 0.12 0.08 97.42 56.62 42.85 0.00 0.00 0.14 0.36 2692 40.71 56.36are 0.00 ordered 0.00 according 0.09 0.10 to decreasing 97.26 Au 56.52 content. 42.85 0.00 0.00 0.10 0.46 2684 40.73 56.06 0.00 0.00 0.09 0.08 96.95 56.76 42.79 0.00 0.00 0.10 0.35 4.8.3. Uytenbogaardtite 2685 40.95 Ag3AuS2 56.31 0.00 0.00 0.10 0.08 97.44 56.71 42.71 0.00 0.00 0.12 0.38 2683 40.92 55.84 0.00 0.00 0.06 0.08 96.90 56.92 42.54 0.00 0.00 0.07 0.36 Uytenbogaardtite 2690 41.15 was found 55.88 as 0.00 one semi-euhedrall 0.00 0.12 0.12 grain 97.269 56.94 6 μm in 42.34 massive 0.00 miargyrite 0.02 0.13 of red 0.54 ore (ii). The 2691 image in 41.41 Figure 55.53 25a reveals 0.00 that 0.00 the 0.09 grain 0.09contains 97.12 minute 57.34 inclusions 42.11 0.00 of Au-rich 0.00 0.10 silver 0.41 (white spots, 2688 one larger 41.89 one is 55.68 visible 0.00 at the 0.00 left edge 0.00 of 0.10 the grain) 97.66 with 57.5951.0 41.92 of 0.00 Au and 0.0046.3 0.03 0.46 of Ag (corresponding 2687 41.86 to 35.7 55.59 at.% Au), 0.00 which 0.00 are 0.12 probably 0.09 97.66 responsible 57.58 for 41.87 the lower 0.00 sulphur 0.00 0.14 content 0.41 2571 48.58 47.84 0.00 0.29 0.11 0.07 96.90 64.42 34.74 0.00 0.34 0.13 0.33 in the measured points of uytenbogaardtite. The top and right edge of the grain displays a hem 2572 50.57 45.87 0.20 0.36 0.11 0.09 97.19 66.10 32.83 0.14 0.41 0.13 0.39 resembling 2630 a reaction 49.52 product. 42.53 However, 0.97 0.85 the hem 0.00is 2.87 formed 96.73 by uytenbogaardtite 59.11 27.80 0.62 with 0.90 increased 0.02 Sb 11.52 content, a possible 2627 contamination 56.48 39.40 from 0.52surrounding 0.83 0.15 miargyrite. 0.76 98.14 69.06 26.38 0.34 0.90 0.16 3.13 This is 2573the first 59.18 occurrence 36.84 0.48of 0.58 uytenbogaardtite 0.09 0.53 97.70 in 72.14 the Czech 24.60 Republic. 0.31 0.63 Recently, 0.09 2.17 uytenbogaardite 2574 was 59.43 described 36.62 from 0.00 the 0.74selenium-rich 0.10 0.57 97.46 Au-Ag 72.35 mineralization 24.41 0.00 of the 0.80Kremnica 0.11 2.33 Sb-Au-Ag epithermal 2575 62.13 deposit, 33.51 Slovakia 0.00 [72]. 1.07 The 0.12chemistry 0.44 97.27 of uytenbogaardtite 74.86 22.11 0.00 from 1.15 Kutná 0.13 Hora 1.76 2749 61.73 32.85 0.00 1.20 0.00 0.69 96.48 73.96 21.56 0.00 1.28 0.00 2.77 (Table 26) shows a surplus of silver (3.16 3.33 apfu) and a deficit of sulphur (1.66 1.87 apfu) at all four 2629 63.97 31.35 0.30 1.69 0.14 1.18 98.64 73.60 19.75 0.18 1.73 0.14 4.57 analysed points. 2628 Two 66.73 analyses 27.60 show 0.28 a surplus 2.19 0.18 of gold 1.76 (1.14 98.73 apfu), 74.11 and two 16.78 show 0.17 a deficit 2.15 (0.77 0.17 and 6.57 0.87 apfu). We assume that the lower sulphur contents compared to stoichiometry are caused by the are ordered according to decreasing Au content. fact that the grain is, in fact, a submicroscopic intergrowth of uytenbogaardtite with Au-rich silver, which is visible on the BSE photograph (Figure 25a). at% (a) (b) Uyt Uyt Dys Aca Dys Aca Mia 20 m 20 m Figure 25. (a) Grain of uytenbogaardtite (Uyt) in miargyrite (Mia), inclusions of Au rich silver (white) Figure 25. (a) Grain of uytenbogaardtite (Uyt) in miargyrite (Mia), inclusions of Au rich silver (white) are visible at the left edge of the grain. (b) grain of Au-rich dyscrasite (Dys) in quartz of red ore (ii). are visible at the left edge of the grain. (b) grain of Au-rich dyscrasite (Dys) in quartz of red ore Au-rich dycrasite (3.7 4.1 of Au) replaces acanthite (Aca). Both back-scattered electron (BSE) (ii). Au-rich dycrasite (3.7 4.1 of Au) replaces acanthite (Aca). Both back-scattered electron images. (BSE) images. Table 26. EPMA data for uytenbogaardtite. This is the first occurrence of uytenbogaardtite in the Czech Republic. Recently, uytenbogaardite was described from the selenium-rich Au-Ag mineralization of apfu theʃ6 Kremnica atoms Sb-Au-Ag epithermal deposit, Slovakia [72]. The Ag chemistry Au of Sb uytenbogaardtite S Total Ag fromau KutnáSb Hora S (Table 26) shows a surplus of silver (3.16 3.33 2951 apfu) and 54.74 a deficit 36.03 of 0.61 sulphur 8.55 (1.66 1.87 99.93 3.16 apfu) at 1.14 all four 0.03 analysed 1.66 points. Two analyses show a surplus2952 of gold 55.39 (1.14 apfu), 36.33 and 0.64 two 8.61 show100.97 a deficit 3.17 (0.77 1.14 and 0.030.87 1.66 apfu). We assume that the lower sulphur contents 2955 59.93 compared 29.31 to0.74 stoichiometry 10.31 100.29 are3.23 caused 0.87 by0.04 the fact 1.87 that the grain is, in fact, a submicroscopic 2957 intergrowth 61.73 25.93 of uytenbogaardtite 0.85 10.27 98.79 with3.33 Au-rich 0.77 silver, 0.04 1.86 which is visible on the BSE photograph (Figure 25a). 4.8.4. Allargentum, Ag6Sb Allargentum (together with Sb-rich silver) is more abundant than native Sb-free silver in the hypogene mineralization. It is found as metallic white-yellow outgrowths, platelets or wire-like aggregates, usually up to several mm in size in the cavities of quartz kutnohorite gangue of red ore (ii), associated with silver, pyrargyrite and miargyrite. In polished sections, it occurs as anhedral aggregates up to several hundred μm in size in miargyrite, associated with pyrargyrite and acanthite (Figure 18a).

Minerals 2019, 9, 430 36 of 47 Table 26. EPMA data for uytenbogaardtite. apfu Σ6 atoms Ag Au Sb S Total Ag Au Sb S 2951 54.74 36.03 0.61 8.55 99.93 3.16 1.14 0.03 1.66 2952 55.39 36.33 0.64 8.61 100.97 3.17 1.14 0.03 1.66 2955 59.93 29.31 0.74 10.31 100.29 3.23 0.87 0.04 1.87 2957 61.73 25.93 0.85 10.27 98.79 3.33 0.77 0.04 1.86 4.8.4. Allargentum, Ag 6 Sb Allargentum (together with Sb-rich silver) is more abundant than native Sb-free silver in the hypogene mineralization. It is found as metallic white-yellow outgrowths, platelets or wire-like aggregates, usually up to several mm in size in the cavities of quartz kutnohorite gangue of red ore (ii), associated with silver, pyrargyrite and miargyrite. In polished sections, it occurs as anhedral aggregates up to several hundred µm in size in miargyrite, associated with pyrargyrite and acanthite (Figure 18a). The chemical composition of allargentum is relatively uniform and is close to the ideal formula (Table 27, Figure 23); only traces of Cl were identified. The empirical formula for studied allargentum samples on the basis of 7 apfu (mean of 10 analyses) can be expressed as Ag 5.95 Sb 1.02 Cl 0.02. Table 27. EPMA data for allargentum. apfu Σ7 atom Ag Au Sb As Cl Total Ag Au Sb As Cl 2812 84.28 0.00 16.46 0.05 0.09 100.88 5.94 0.00 1.03 0.01 0.02 2832 84.75 0.00 16.29 0.00 0.09 101.13 5.96 0.00 1.01 0.00 0.02 2841 84.74 0.00 16.49 0.00 0.10 101.33 5.94 0.00 1.02 0.00 0.02 2842 84.21 0.00 16.42 0.00 0.10 100.73 5.94 0.00 1.03 0.00 0.02 2843 84.60 0.09 16.32 0.06 0.08 101.15 5.95 0.00 1.02 0.01 0.02 2846 84.29 0.00 16.30 0.00 0.10 100.69 5.95 0.00 1.02 0.00 0.02 2847 84.54 0.00 16.34 0.00 0.08 100.96 5.95 0.00 1.02 0.00 0.02 4.8.5. Au-rich Dyscrasite (Ag,Au) 3 Sb Au-rich dyscrasite was found as one anhedral grain 60 x 30 µm in quartz, close to, but not in direct contact with, the massive miargyrite of red ore (ii) (Figure 25b). The chemical analysis of dyscrasite (Table 28) revealed interesting contents of Au in the range 0.08 0.10 apfu (3.65 4.11 ). A small deficit of Sb observed up to 0.08 apfu (Figure 23) corresponds to the ideal formula Ag 3 + x Sb 1 x proposed for dyscrasite by Scott [73] on the basis of crystal structure study. Table 28. EPMA data for Au-rich dyscrasite. apfu Σ4 atom Ag Au Sb Te S Total Ag Au Sb Te S 2760 70.84 3.65 24.66 0.13 0.07 99.35 2.98 0.08 0.92 0.00 0.01 2761 69.83 3.92 26.50 0.06 0.05 100.35 2.92 0.09 0.98 0.00 0.01 2762 67.81 4.11 26.98 0.00 0.21 99.10 2.87 0.10 1.01 0.00 0.03

Minerals 2019, 9, 430 37 of 47 4.9. Galena Clausthalite Solid Solution 4.9.1. Galena Galena is a very frequent mineral in the Pb-rich black ore (i) from Vein B. It occurs as typical lead-grey cleavable grain aggregates several cm in size associated with other sulfides, occasionally as crystals in cavities. In polished sections, it was frequently found as the earliest mineral associated with boulangerite, freieslebenite, diaphorite, owyheeite, andorite group minerals, miargyrite and freibergite (Figure 2a c,e, Figure 4, Figure 5c,d, Figure 8, Figure 10b, Figure 12a). It is also frequently found in the red ore type (ii) as plentiful bubble-shaped inclusions in pyrite (Figure 21b), and also as idiomorphic grains; usually, it is the earliest mineral. Very frequently, it occurs as filling of bubble-shaped inclusions in the pyrite of red ore (ii) (Figure 15a,b, Figure 16b, Figure 18b,c,d, Figure 20a,b, Figure 21a,b). It also occurs in ore (iii) (Figure 2f). Increased Se contents (Table 29) were found only in small grains of galena (up to 20 µm across), associated with various Ag-Pb-Sb sulfosalts. Significantly increased Ag contents (up to 12.34 ) were occasionally identified (34 points above 1 of Ag). These were found to be positively correlated with Sb contents (Figure 26a) and considerably higher than previously reported in the literature from this locality (0.10 0.21 [13,35]). Ag and Sb enter the structure of galena probably by the same mechanism as Ag and Bi in PbS SS, i.e., galena matildite solid solution [74,75]. The maximum values of Ag and Sb in the galena grains are 0.22 apfu and 0.23 apfu. Sucha high degree of substitution was observed only in several grains and corresponds to the highest contents of PbS SS ([74,76,77]. In most studied galena grains, the contents of Ag do not exceed 0.12 apfu; a similar range of Ag + (Bi,Sb) 2Pb substations in PbS SS are known from other occurrences around the world [23,74,75,77]. Measured contents of Se in galena (Table 29) are substantially higher than previously published data (0.14 Se [13]) and suggest an unlimited SeS 1 substitution in galena clausthalite solid solution (Figure 26b); as mentioned before, higher Se contents were determined for smaller aggregates of galena, usually not exceeding 20 µm. Table 29. EPMA data for galena. apfu Σ2 atom Ag Cu Pb Sb Se S Total Ag Cu Pb Sb Se S 2467 0.04 0.00 85.74 0.15 0.00 13.35 99.29 0.00 0.00 0.99 0.00 0.00 1.00 2013 0.09 0.05 85.80 0.13 0.19 13.49 99.75 0.00 0.00 0.98 0.00 0.01 1.00 857 0.00 0.00 85.81 0.19 0.44 13.59 100.04 0.00 0.00 0.98 0.00 0.01 1.00 2215 0.28 0.00 84.26 0.78 1.10 13.23 99.65 0.01 0.00 0.96 0.02 0.03 0.98 372 0.88 0.00 83.74 1.06 1.53 13.18 100.38 0.02 0.00 0.94 0.02 0.05 0.96 1264 0.21 0.00 83.85 0.28 2.57 12.38 99.29 0.00 0.00 0.97 0.01 0.08 0.93 2266 1.37 0.00 82.57 0.08 3.34 11.91 99.27 0.03 0.00 0.96 0.00 0.10 0.89 1494 0.08 0.00 84.30 0.16 3.64 11.92 100.11 0.00 0.00 0.98 0.00 0.11 0.90 23 0.13 0.31 84.51 0.09 3.83 12.03 100.90 0.00 0.01 0.97 0.00 0.12 0.89 2264 1.67 0.00 82.73 0.09 4.63 11.54 100.66 0.04 0.00 0.95 0.00 0.14 0.86 2315 1.29 0.00 82.87 0.07 5.10 10.84 100.17 0.03 0.00 0.98 0.00 0.16 0.82 22 0.20 0.31 83.63 0.08 5.38 11.12 100.72 0.00 0.01 0.97 0.00 0.16 0.84 2265 1.53 0.00 81.15 0.08 6.57 10.68 100.01 0.03 0.00 0.95 0.00 0.20 0.81 754 0.05 0.00 82.87 0.12 6.67 10.55 100.26 0.00 0.00 0.98 0.00 0.21 0.81 2314 1.01 0.00 82.32 0.06 6.82 9.98 100.19 0.02 0.00 0.98 0.00 0.21 0.77 1262 0.30 0.00 79.39 0.32 14.02 7.09 101.12 0.01 0.00 0.97 0.01 0.45 0.56 are ordered according to incereasing Se content.

2Pb substations in PbSSS are known from other occurrences around the world [23,74,75,77]. Measured contents of Se in galena (Table 29) are substantially higher than previously published data (0.14 Se [13]) and suggest an unlimited SeS-1 substitution in galena clausthalite solid solution (Figure 26b); as mentioned before, higher Se contents were determined for smaller aggregates of galena, usually not exceeding 20 μm. Minerals 2019, 9, 430 38 of 47 0.25 0.20 (a) 1.2 1.0 (b) galena clausthalite Sb ( apfu) 0.15 0.10 S (apfu) 0.8 0.6 0.05 0.4 0.00 galena clausthalite 0.2 0.0 0.00 0.05 0.10 0.15 0.20 0.25 0.0 0.2 0.4 0.6 0.8 1.0 Minerals 2019, 9, x FOR PEER REVIEW Ag ( apfu) Se ( apfu) 36 of 45 (i) as Figure inclusions 26. (a) up Graph to 50 Ag μm vs Sb in (apfu) Se-free for freieslebenite, members of of galena which clausthalite is replaced solid by solution. clausthalite. (b) graph Generally, Se Se members vs vs S S (apfu) of the for clausthalite-galena members of of clausthalite solid solution solid solution. occurring in black ore (i) are accompanied by 4.9.2. galena Clausthalite and Pb-Sb-(Ag) sulfosalts. Often a common trend is that smaller grains are Se-rich galena or clausthalite and larger grains of galena Table are 29. generally EPMA data Se-free. for galena. Clausthalite It has to be noted is the that mostno frequently sulphur-free occurring clausthalite selenide was mineral. found in It was any found apfu of the Ʃ2 atom measured in both black samples. ore (i) (Figure Sulphur 27) contents (two samples, in Ag clausthalite 10 point analyses) Cu Pb (Table Sb 30) and, Se range even S between more often, Total 0.10 0.50 in red Ag Cu apfu ore (ii) Pb (4.87 6.28 (four samples, Sb Se ) 10 S (Figure point analyses). 26b). An unlimited The mineral 2467 0.04 miscibility was found 0.00 85.74 among as anhedral 0.15 clausthalite grains 0.00 13.35 and ingalena fractures 99.29 was in 0.00 observed freibergite 0.00 0.99 in filled experimental in by miargyrite 0.00 0.00 1.00 studies in of red phase ore (ii) 2013 relations (Figure 0.09 in 16a). this This 0.05 system miargyrite 85.80 0.13 at temperatures shows increased 0.19 13.49 above amounts 99.75 300 0.00 C of 0.00 [78 80]. selenium 0.98 The and 0.00 extrapolation belongs to the 0.01 1.00 of latest thermodynamic minerals of 857 data the association. 0.00 for 0.00 end members Other clausthalite 85.81 0.19 enables 0.44 to 13.59 envisage grains are 100.04 the observed existence in 0.00 0.00 of bubble-shaped 0.98 a complete 0.00 0.01 solid inclusions 1.00 solution in pyrite PbSe PbS of red 2215 up ore to (ii) temperatures (Figure 16b, 0.28 0.00 84.26 of Figure about 20a) 0.78 100 in 1.10 C association 13.23 [79,80]. 99.65 The withexistence Se-rich galena, 0.01 0.00 of 0.96 a complete accompanied 0.02 0.03 isomorphous by other 0.98 minerals series PbS PbSe present 372 in these 0.88 natural inclusions 0.00 samples (see 83.74 1.06 was aguilarite). described 1.53 13.18 for Clausthalite 100.38 the first 0.02 time was identified 0.00 by Coleman among 0.94 0.02 [81], compositions 0.05 who 0.96 studied corresponding samples from to the galena-clausthalite solid solution in black ore (i) as inclusions up to 50 µm in 1264 uranium vanadium 0.21 0.00 83.85 0.28 deposits 2.57 in 12.38 the area 99.29 of Colorado 0.00 0.00 Plateau, 0.97 0.01 and 0.08 later, 0.93 it was Se-free confirmed freieslebenite, which is replaced by clausthalite. Generally, members of the clausthalite-galena 2266 by the research 1.37 0.00 of 82.57 samples 0.08 from 3.34 the deposits 11.91 99.27 of Niederschlema Alberoda 0.03 0.00 0.96 0.00 0.10 [82], 0.89 Moldava solid [83] and solution Potůčky occurring in black ore (i) are accompanied by galena and Pb-Sb-(Ag) sulfosalts. Often a 1494 [84] 0.08 in 0.00 Krušné 84.30 hory 0.16 Mountains 3.64 11.92 or Běstvina 100.11 in 0.00 Železné 0.00 hory 0.98 Mountains 0.00 0.11 [85]. 0.90 Unlike common coexisting trend galena, is that smaller grains are Se-rich galena or clausthalite and larger grains of galena are 23 0.13 clausthalite 0.31 84.51 contains 0.09 very 3.83 rarely 12.03 increased 100.90 contents 0.00 0.01 of Ag 0.97 (and 0.00 Sb), 0.12 not exceeding 0.89 generally 0.11 apfu or Se-free. 2264 0.04 apfu, 1.67 respectively 0.00 82.73 (Figure 0.09 28). 4.63 In 11.54 Table 30, 100.66 the contents 0.04 0.00 of Ag 0.95 and 0.00 Sb are 0.14 negligible. 0.86 2315 1.29 0.00 82.87 0.07 5.10 10.84 100.17 0.03 0.00 0.98 0.00 0.16 0.82 22 0.20 0.31 83.63 0.08 5.38 11.12 100.72 0.00 0.01 0.97 0.00 0.16 0.84 2265 1.53 0.00 81.15 0.08 6.57 10.68 100.01 0.03 0.00 0.95 0.00 0.20 0.81 754 0.05 0.00 82.87 0.12 6.67 10.55 100.26 0.00 0.00 0.98 0.00 0.21 0.81 2314 1.01 0.00 82.32 0.06 6.82 9.98 100.19 0.02 0.00 0.98 0.00 0.21 0.77 1262 0.30 0.00 79.39 0.32 14.02 7.09 101.12 0.01 0.00 0.97 0.01 0.45 0.56 are ordered according to incereasing Clh Se content. 4.9.2. Clausthalite Frs Clausthalite is the most frequently occurring selenide mineral. It was found in both black ore (i) (Figure 27) (two samples, 10 point analyses) and, even Clh more often, in red ore (ii) (four samples, 10 point analyses). The mineral was found as anhedral grains in fractures in freibergite filled in by miargyrite in red ore (ii) (Figure 16a). This miargyrite shows increased amounts of selenium and belongs to the latest minerals of the association. Other clausthalite grains are observed in bubble-shaped inclusions in pyrite of red ore (ii) (Figure 16b, Figure 20a) in association with Se-rich galena, accompanied by other minerals present in these inclusions (see aguilarite). Clausthalite was identified among compositions corresponding to the galena-clausthalite solid solution in black ore Dia 50 m Figure 27. The general succession in Se-enriched black ore (i); clausthalite (Clh 16 of Se) and Se-rich galena (, 2% Se) replaced by freieslebenite (Frs, 0.3% Se) and diaforite (Dia, 3.5% of Se). Back-scattered electron (BSE) image.

Minerals 2019, 9, 430 39 of 47 It has to be noted that no sulphur-free clausthalite was found in any of the measured samples. Sulphur contents in clausthalite (Table 30) range between 0.10 0.50 apfu (4.87 6.28 ) (Figure 26b). An unlimited miscibility among clausthalite and galena was observed in experimental studies of phase relations in this system at temperatures above 300 C [78 80]. The extrapolation of thermodynamic data for end members enables to envisage the existence of a complete solid solution PbSe PbS up to temperatures of about 100 C [79,80]. The existence of a complete isomorphous series PbS PbSe in natural samples was described for the first time by Coleman [81], who studied samples from uranium vanadium deposits in the area of Colorado Plateau, and later, it was confirmed by the research of samples from the deposits of Niederschlema Alberoda [82], Moldava [83] and Potůčky [84] in Krušné hory Mountains or Běstvina in Železné hory Mountains [85]. Unlike coexisting galena, clausthalite contains very rarely increased contents of Ag (and Sb), not exceeding 0.11 apfu or 0.04 apfu, respectively (Figure 28). In Table 30, the contents of Ag and Sb are negligible. Table 30. EPMA data for clausthalite. apfu Σ2 atom Ag Pb Zn Sb Se S Total Ag Pb Zn Sb Se S 303 0.19 77.35 0.50 0.09 16.35 6.36 100.83 0.00 0.94 0.02 0.00 0.52 0.50 239 0.05 78.52 0.41 0.06 16.32 5.90 101.26 0.00 0.97 0.02 0.00 0.53 0.47 1263 0.00 78.73 0.00 0.08 17.01 5.62 101.44 0.00 0.98 0.00 0.00 0.56 0.45 1255 0.05 78.43 0.00 0.10 17.60 5.66 101.83 0.00 0.98 0.00 0.00 0.58 0.43 1260 0.06 77.86 0.00 0.07 18.36 4.94 101.29 0.00 0.98 0.00 0.00 0.61 0.40 Minerals 1261 2019, 0.00 9, x FOR 76.47 PEER REVIEW 0.00 0.08 18.74 4.87 100.16 0.00 0.97 0.00 0.00 0.62 0.40 37 of 45 are ordered according to increasing Se content. 0.5 (Ag+Sb)/(Ag+Sb+Pb) 0.4 0.3 0.2 0.1 0.0 galena clausthalite 0.0 0.2 0.4 0.6 0.8 1.0 Se/(Se+S) Figure Figure 28. 28. Graph Graph Se/(Se Se/(Se + S) + vs. S) vs. (Ag (Ag + Sb)/(Ag + Sb)/(Ag + Sb + Sb + Pb) + Pb) (apfu) (apfu) for for members of of galena galena clausthalite solid solid solution. solution. 5. Discussion Table 30. EPMA data for clausthalite. 5.1. Succession of Crystalization apfu Ʃ2 atom The ore mineralization Ag Pb of the Zn wholesb KutnáSe HoraS ore district Total originated Ag Pb inzn several Sb stages, Se separated S by tectonic movements 303 0.19 [26]. 77.35 Each 0.50 stage 0.09 is16.35 subdivided 6.36 100.83 into mineralization 0.00 0.94 0.02 sequences, 0.00 0.52 divided 0.50 by weaker tectonic 239 events 0.05 or by 78.52 distinct 0.41 metasomatic 0.06 16.32 processes. 5.90 101.26 The 0.00 similarity 0.97 of 0.02 the Kutná 0.00 0.53 Hora 0.47 [26] and 1263 0.00 78.73 0.00 0.08 17.01 5.62 101.44 0.00 0.98 0.00 0.00 0.56 0.45 1255 0.05 78.43 0.00 0.10 17.60 5.66 101.83 0.00 0.98 0.00 0.00 0.58 0.43 1260 0.06 77.86 0.00 0.07 18.36 4.94 101.29 0.00 0.98 0.00 0.00 0.61 0.40 1261 0.00 76.47 0.00 0.08 18.74 4.87 100.16 0.00 0.97 0.00 0.00 0.62 0.40 are ordered according to increasing Se content.

Minerals 2019, 9, 430 40 of 47 Freiberg [29] districts leads us to compare the nomenclature of the succession schemes in both districts (Table 31). Table 31. Comparative table of mineral sequences in Kutná Hora and Freiberg. Kutná Hora Freiberg [29] Stage Sequence Ore type Sequence I. II. III. IV. Ia. Fe-As Ib. Zn-Sn-Cu-Fe Ic. 1stcarbonate IIa. Pb-Ag IIb.2nd carbonate kb Fe-As Zn-Sn-Cu Pb-Ag IIIa. Ag-Sb eb, eq Ag-Sb IIIb. Sb-Fe quartz pyrite calcite kb kiesig-blendige Bleierzformation ; eb ; eq edle Braunspatformation ; edle Quarzformation. The veins of northern pyrite-rich lodes are characterized by the presence of the first two stages: Fe-As sequence (Ia); Zn-Sn-Cu-Fe sequence (Ib) and Pb-Ag sequence (IIa). Also present in northern lodes though on smaller scale than in the south is the later third stage: Ag-Sb sequence (IIIa) and Sb-Fe sequence (IIIb). On the contrary, the southern silver-rich lodes are characterized by a much smaller presence of the first two stages and a complete absence of Sn in Ib sequence and an almost exclusive representation of the stage III with frequent kutnohorite in gangue [8,86]. The Oselské pásmo Lode, including the newly studied mineralization of Anthony of Padua mine (this paper) are a typical example of southern "silver-rich" lodes and the origin of this ore mineralization is bound to the youngest Ag Sb sequence (IIIa). On the basis of published data as well as of new study (this paper), it was possible to single out several fundamental types (kinds) of ore: the Pb-rich black ore (i); the Ag-rich red ore (ii) in quartz kutnohorite gangue; the Ag-rich ore (iii) in quarz gangue (see Section 4.1). Several hundred BSE images of seventy measured polished sections were examined and conclusions regarding associations and parageneses drawn. The succession of minerals in individual samples was determined where possible. Several trends, general features and repeated patterns were observed. The general succession follows the trend from Pb-rich phases to Pb-poorer (Ag-richer) phases. The earliest mineral in all three types of ore is galena. (i) black ore Pb-rich black ore in quartz with the general succession: galena boulangerite ( jamesonite) owyheeite fizélyite Ag-excess fizélyite andorite IV andorite VI freieslebenite diaphorite miargyrite freibergite. This belongs to Ag-Sb sequence IIIa, corresponding in the Freiberg succession scheme to Ag-Sb sequence of eb ore type or the transitional ore type between kb and eb, with an overprint of Se mineralization. (ii) red ore the Ag-rich red ore in kutnohorite + quartz. Three succession patterns are noticeable: one is galena diaphorite freibergite miargyrite pyragyrite stephanite polybasite acanthite; the second is galena allargentum pyrargyrite Sb-rich silver silver (Sb-free) acanthite; and the third is galena freibergite argyrodite unnamed Ag-Cu-S phases (a reverse trend of argyrodite being replaced by freibergite was occasionally observed). Concerning the position of gold alloys in the succession, the only observable examples are: Au-rich silver uytenbogaardtite miargyrite; sphalerite Au-rich silver freibergite; and Au-rich silver miargyrite. This corresponds to Ag-Sb sequence IIIa, with overprints of Se, Ge and Au mineralizations, corresponding to eb ore type, and the Ag-Sb sequence in Freiberg. (iii) Ag-rich ore in milky quartz consists of crystals in cavities, bands and lenses of Ag minerals (mainly miargyrite), base sulfides are scarce. The usual succession is: galena freieslebenite diaphorite freibergite miargyrite pyrargyrite/pyrostilpnite stephanite acanthite. It belongs to Ag-Sb

Minerals 2019, 9, 430 41 of 47 sequence III, with a weaker overprint of Se mineralization; corresponds to eq ore type, Ag-Sb sequence in Freiberg. The second, parallel succession scheme progresses from Se-free through Se-poor to Se-rich phases, such as: galena members of galena - clausthalite solid solution clausthalite; miargyrite Se-rich miargyrite; acanthite aguilarite naumannite etc. The mutual relationship between the three ores (i, ii and iii) is difficult to assess with regard to their occurrences in different veins. The authors of this article are of the opinion that the Pb-rich black ore (i) is the earliest of the three, followed by (ii) and (iii). 5.2. Discussion of the Formation Conditions The Kutná Hora ore district is considered a typical example of postmagmatic sulfide base-metal mineralization of late Variscan age (Early Permian; [87]), analogous to the kb + eb ore types (mineralizations) of Freiberg in Saxony, Germany [28,29]. Silver minerals ( eb, the Ag-Sb sequence in Freiberg) in the whole Kutná Hora ore district occur mostly on independent younger structures (Ag-Sb sequence IIIa) within the vein system; marked differences between the southern (dominant stage III (i.e. eb and eq ore type), weaker stage II ( kb ) and northern lodes (dominant stage I and II ( kb ), weaker stage III ( eq ) are primarily caused by a different geological (petrological, tectonic) structure of both parts [26]. Bernard and Žák [88] suggested that mineralization of Kutná Hora ore district generally originated at high temperatures (430 ± 80 C + kb stage); younger parts of the mineralization ( eb/eq stage) were colder (< 190 C; [89]). According to Seifert and Sandmann [29] an analogous Ag-Sb mineralization from the Freiberg district ( eb ore type) originated at temperatures between 300 120 C. They also mention possible mineralogical and geochemical similarities to epithermal-style Ag-Au mineralization [90,91]. The similarity of the studied Ag-Sb mineralization from southern silver-rich lodes of the Kutná Hora ore district with the eb ore type of the Freiberg district is highlighted by the newly discovered germanium-bearing mineral argyrodite and by Au and Se presence in Kutná Hora correlating with the argyrodite occurrence and locally increased Au and Se contents in eb ores of the Freiberg district [29]. The character of the discovered selenium mineralization (i.e., increased selenium contents in Agand Pb-Sb sulfosalts, the occurrence of minerals of galena clausthalite solid solution, and Se-rich acanthite, aguilarite and naumannite) indicates the formation from hydrothermal fluids with f O2 slightly above or close to hematite - magnetite buffer and the f Se2 /f S2 ratio close to unity. The presence of minerals of galena clausthalite solid solution shows that the upper values of the f Se2 /f S2 ratio were more likely controlled by the galena clausthalite buffer, which is still close to unity [92,93]. The occurrence of naumannite and acanthite which was deposited together with silver and Ag-sulfosalts requires conditions close to the native Ag-naumannite + acanthite invariant point [93,94]. Together with observed minerals of the galena clausthalite solid solution it is possible to define a f Se2 range of 23 to 26 and a f S2 range of 21 to 22, respectively [93,94]. These values correspond very well with conditions published for selenide-bearing Au-Ag epithermal deposits by Simon et al. [93]. Although Kutná Hora ore district including Anthony of Padua mine is not a volcanic low-sulfidation epithermal deposit, the studied mineralization shows many similar features. The source of selenium is probably in the bodies of (meta)ultrabasic rocks (serpentinites) frequently found by boreholes in southern silver lodes both south of town, as well as in its historic centre. The topomineral properties of these rocks may enable to pre-concentrate selenium which was released into hydrothermal fluids during tectonic events. The amphibolite from the quarry of Markovice, 10 km SE of Kutná Hora, known up to now only for the occurrence of zeolites, was recently found to contain selenides, tellurides and native tellurium [95,96]. The origin of selenides and tellurides from this locality is assumed to be related to (meta)ultrabasic rocks cutting through amphibolite rocks. A similar situation is also known from the northern part of the Kongsberg deposit, Norway [97].

Minerals 2019, 9, 430 42 of 47 6. Conclusions (1) The previously unknown selenium mineralization (clausthalite, naumannite, aguilarite) and increased selenium contents in Ag- and Pb-Sb sulfosalts were determined in hydrothermal ore veins from Anthony of Padua mine near Poličany. These veins are part of the Oselské pásmo Lode, one of the southern silver-rich lodes of the historic Kutná Hora ore district. The determined contents of Se in Ag- and Pb-Sb sulfosalts belong to the highest ever found worldwide. (2) A suite of more than twenty silver minerals were determined in samples from Anthony of Padua mine: Ag-Pb-Sb sulfosalts (Ag-excess fizélyite, fizélyite, andorite IV, andorite VI, diaphorite, freieslebenite, owyheeite), Ag-Sb-(Cu)-sulfosalts (miargyrite, pyrargyrite, stephanite, polybasite, freibergite, Ag-rich tetrahedrite), Ag-sulfides and selenides (acanthite, aguilarite, naumannite, argyrodite), native elements, Ag, Au sulfides and antimonides (native silver and its Sb- or Au-rich variety, allargentum, Au-rich dyscrasite, uytenbogaardtite) and unnamed Ag-poor Ag-Pb-Sb sulfosalts and Ag-Cu-S mineral phases. The Pb-Sb sulfosalts (boulangerite, semseyite, jamesonite), and lead sulfide and selenide (members of galena clausthalite solid solution) were also determined. (3) Three kinds of ore were identified in studied samples: Pb-rich black ore (i), Ag-rich red ore (ii) in quartz kutnohorite gangue, and Ag-rich ore (iii) in quarz gangue without sulfides. The general succession follows the trend from Pb-rich phases to Pb-poorer and Ag-richer phases. The earliest mineral is galena. The general successions scheme is for the Pb-rich black ore (i) as follows: galena boulangerite ( jamesonite) owyheeite fizélyite Ag-exces fizélyite andorite IV andorite VI freieslebenite diaphorite miargyrite freibergite. For the Ag-rich red ore (ii) and ore (iii), the most prominent pattern is galena diaphorite freibergite miargyrite pyragyrite stephanite polybasite acanthite. The parallel succession scheme progresses from Se-poor to Se-rich phases, for example, galena members of galena - clausthalite solid solution clausthalite; miargyrite Se-rich miargyrite; acanthite aguilarite naumannite; etc. (4) The observed Ag-rich mineral association provides an insight into the character of exploited ore on historic silver-rich lodes from the south of the Kutná Hora ore district, such as Oselské pásmo Lode and Roveňské pásmo Lode, which were the main silver deposits of Kutná Hora district in the 14th century. It is evident that silver minerals such as miargyrite and freibergite were the main sources of silver, and not the alleged low contents of Ag in base-metal sulfides (most frequently as inclusions of Ag minerals) like on northern lodes. (5) The origin of economic silver mineralization of southern silver-rich lodes of the Kutná Hora district is bound primarily to the youngest Ag-Sb sequence IIIa, corresponding to the Ag-Sb sequence of the eb/eq ore types in the Freiberg succession scheme. Earlier stages with base sulfide sequences, e.g., Zn-Sn-Cu-Fe sequence Ib and Pb-Ag sequence IIa, corresponding to the kb ore type, which are abundantly present on lodes in the northern part of the Kutná Hora district, are much less developed (Pb-Ag sequence IIa) or missing (Zn-Sn-Cu-Fe sequence Ib). The described Ag-Sb mineralization of the Kutná Hora ore district is analogous to the Ag-Sb sequence of the younger eb/eq ore type (mineralization) of the Freiberg district, Saxony, Germany, including a local minority presence of Ge, Au and Se minerals. (6) The ore mineralization of the Kutná Hora ore district is a typical example of postmagmatic sulfide hydrothermal mineralization of late Variscan age. The Ag-rich mineralization of southern silver-rich lodes originated under temperatures significantly lower (< 190 C) than the earlier mineralization of northern lodes (430 ± 80 C); lower temperatures (300 120 C) are stated in the literature for the origin of the analogous eb mineralization (ore type) of the Freiberg district, Saxony, Germany. (7) The association found between selenides and other Se-bearing mineral phases indicates hydrothermal fluids with f O2 slightly above or close to hematite-magnetite buffer and af Se2 /f S2 ratio close than unity: the ranges are -23 to -26 and -21 to -22 for f Se2 and f S2, respectively. These values correspond very well to conditions published for selenide-bearing Au-Ag epithermal deposits. The mineralogical and geochemical similarities of the entirety of the latest eb ore type (mineralization) of the Freiberg ore district and the low-sulfidation epithermal-style Ag Au mineralization have been published previously.

Minerals 2019, 9, 430 43 of 47 (8) The source of seleniumin Kutná Hora is probably related to the bodies of (meta)ultrabasics (serpentinites) frequently found by boreholes in southern silver lodes both south of town and in its historic centre. The topomineral properties of these rocks may enable to pre-concentrate selenium which was released into hydrothermal fluids during tectonic events. Author Contributions: R.P. collected samples and processed EMPA data. R.P., J.S. and V.Š. interpreted the results, V.Š. carried out ore microscopy and succession studies; R.P. and J.S. wrote the paper. Funding: The research was financially supported by the Czech Science Foundation (GAČR project 15-18917S) to RP and by the Ministry of Culture of the Czech Republic (long-term project DKRVO 2019 2023/1.I.a; National Museum, 00023272) for JS, and Project Nr. 528006 of the Czech Geological Service of the Czech Ministry of Environment for VS. Acknowledgments: The authors thank Ivo Macek and Zdeněk Dolníček (National Museum, Prague), Martin Racek and Radim Jedlička (Charles University, Prague) for their kind cooperation with EPMA analyses. Anonymous referees, as well as guest editor are acknowledged for comments and suggestions that helped greatly to improve the manuscript. Conflicts of Interest: The authors declare no conflict of interest. References 1. Bílek, J. Mining in Kutná Hora 9, Historic overwiev; Kuttna: Kutná Hora, Czech Republic, 2001; pp. 1 100. 2. Ettler, V.; Sejkora, J.; Drahota, P.; Litochleb, J.; Pauliš, P.; Zeman, J.; Novák, M.; Pašava, J. Příbram and Kutná Hora mining districts From historical mining to recent environmental impact. Acta Miner. Petr 2010, 7, 1 23. 3. Mikuš, M.; Hušpauer, M. Final Report of the the Kutná Hora ore District Research, Project Nr. 01 78 2107 The basement of the Cretaceouss; Unpublished work. 1988. (in Czech) 4. Mikuš, M.; Hušpauer, M.; Holub, M.; Holub, Z.; Holubová, V.; Rosengranz, O. Final Report of the Research Project Kutná Hora Ore District The Final Evaluation of the Geological Survey of Ores. Raw Material: Zn, Ag, Cu and Pb Ores, Unpublished work. 1994. (in Czech) 5. Bílek, J. Kutná Hora Mining 2, Roveňské pásmo Lode; Kuttna: Kutná Hora, Czech Republic, 2000; pp. 1 60. 6. Bílek, J. Kutná Hora Mining 6, Survey Mining Works in Kutná Hora Ore District; Kuttna: Kutná Hora, Czech Republic, 2000; pp. 1 64. 7. Bílek, J. Mining in Kutná Hora 7, Oselské pásmo Lode; Kuttna: Kutná Hora, Czech Republic, 2000; pp. 1 56. 8. Holub, M. Kutná Hora ore district deposit appendix. Kutnohor. Vlastivěd.Sbor. 2009, 11, 1 21. (in Czech). 9. Vepřek, J.; Hoffmanová, A.; Hoffman, V.; Trdlička, Z. Mineralogich-chemische forschung des gedingen Silbers aus dem Erzrevier von Kutná Hora. Sbor. Nár. Muz. Praze 1974, 30, 163 172. 10. Hoffman, V.; Trdlička, Z. Akanthit (Ag2S) von Kutná Hora (Tschechoslowakei). Chem. der Erde 1974, 33, 276 281. 11. Pažout, R.; Šrein, V.; Korbelová, Z. An unusual Ni-Sb-Ag-Au association of ullmannite, allargentum, Au-rich silver and Au-bearing dyscrasite from Oselské pásmo silver Lode of Kutná Hora Pb-Zn-Ag ore district (Czech Republic). J Geosci. 2017, 62, 247 252. [CrossRef] 12. Hoffman, V.; Trdlička, Z.; Hulínský, V.; Langrová, A.; Arnoldová, V. Mineralogisch- chemisches Studium des Diaphorits von Kutná Hora (ČSSR). Chem. Erde 1977, 36, 36 44. 13. Hoffman, V.; Trdlička, Z. Mineralogical and chemical character of Kutná Hora ore veins. Sbor. geol. Věd (Praha) 1981, 17, 63 105. (in Czech). 14. Hoffman, V.; Trdlička, Z. Freieslebenite from Kutná Hora. Čas. Mineral. Geol. 1977, 4, 429. (in Czech). 15. Kutina, J. Morphology of miargyrite from Kutná Hora. Rozpr. Čes. Akad. Věd 1951, 61, 1 17. (in Czech). 16. Hoffamn, V.; Trdlička, Z. Owyheeite from Kutná Hora A new mineral for Czechoslovakia. N. Jb. Miner. Mh. 1978, H2, 45 57. 17. Mrázek, Z.; Zeman, M. Pyrostlilpnite from Kutná Hora. Čas. Mineral. Geol. 1981, 26, 432. (in Czech). 18. Kvaček, M.; Novák, F.; Drábek, M. Canfieldite and silver-rich tetrahedrite from the Kutná Hora ore district. Neues Jahrb. Mineral. Mh. 1975, r71, 179. 19. Hoffman, V.; Šrein, V.; Trdlička, Z. Sb-gustavite and bouronite from Kutná Hora. Věst.Ústř.úst.geol. 1989, 64, 313 316. (in Czech).

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