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.

A new, previously unknown association of Pb-Bi-Sb-Ag sulphosalt minerals has been found in samples from mine dumps of the Staročeské pásmo Lode of the Kutná Hora Ag-Pb-Zn ore district, central Bohemia, Czech Republic. These minerals form polymineral aggregates up to 1-3 cm in quartz or base sulphides. Apart from numerous members of lillianite homologous series, new occurrences of aramayoite, bismuthinite, cosalite, ikunolite, izoklakeite, matildite, galena ss , Bi-rich jamesonite, Bi-rich boulangerite, Bi-rich owyheeite and Bi-rich semseyite have been identified. An extraordinary extent of the Bi-Sb substitution is characteristic of the studied association. Bi-rich mineralization of this scope has not been previously known from the Kutná Hora ore district. The origin of this sulphosalt mineralization is related to the penetration of lower temperature fluids (c. 100-250 °C) into tectonically opened fractures in older ore veins filling. Virtually no mobilization of elements from the earlier vein filling took place; hydrothermal fluids must have been relatively rich in Ag and Pb and simultaneously poor in Cu. High Bi content was characteristic of the initial stage of the mineralization. Gradually, the Bi/Sb ratio decreased considerably with more Sb-rich minerals originating. At the final stage, Bi-rich Pb-Sb sulphosalts with lower Ag contents crystallized.

A new mineral species, staročeskéite, ideally Ag_0.70Pb_1.60(Bi_1.35Sb_1.35)_Σ2.70S₆, has been found at Kutná Hora ore district, Czech Republic. The mineral occurs in the late-stage Bi-mineralization associated with other lillianite homologues (gustavite, terrywallaceite, vikingite, treasurite, eskimoite and Bi-rich andorite-group minerals) and other bismuth sulfosalts (izoklakeite, cosalite and Bi-rich jamesonite) in quartz gangue. The mineral occurs as lath shaped crystals or anhedral grains up to 80 µm × 70 µm, growing together in aggregates up to 200 µm × 150 µm across. Staročeskéite is steel-grey in colour and has a metallic lustre, the calculated density is 6.185 g/cm³. In reflected light staročeskéite is greyish white; bireflectance and pleochroism are weak with greyish tints. Anisotropy is weak to medium with grey to bluish grey rotation tints. Internal reflections were not observed. The empirical formula based on electron probe microanalyses and calculated on 11 apfu is: (Ag_0.68Cu_0.01)_Σ0.69(Pb_1.56Fe_0.01Cd_0.01)_Σ1.58(Bi_1.32Sb_1.37)_Σ2.69(S_6.04Se_0.01)_Σ6.05. The ideal formula is Ag_0.70Pb_1.60(Bi_1.35Sb_1.35)_Σ2.70S₆, which requires Ag 7.22, Pb 31.70, Bi 26.97, Sb 15.72 and S 18.39 wt.%, total 100.00 wt.%. Staročeskéite is a member of the lillianite homologous series withN= 4. Unlike gustavite and terrywallaceite, staročeskéite, similarly to lillianite, is orthorhombic, space groupCmcm, witha= 4.2539(8),b= 13.3094(8),c= 19.625(1) Å,V= 1111.1(2) ųandZ= 4. The structure of staročeskéite contains four sulfur sites and three metal sites: one pure Pb site and two mixed sites,M1 (0.52Bi + 0.356Ag + 0.124Sb) andM2 (0.601Sb + 0.259Pb + 0.14Bi). The mineral is characterized by the Bi:Sb ratio 1:1 (Bi/(Bi + Sb) = 0.50) and the Ag⁺+ Bi³⁺, Sb³⁺↔ 2 Pb²⁺substitution (L%) equal to 70%. Thus the mineral lies between two series of the lillianite structures withN= 4, between the lillianite–gustavite series and the andorite series.

A new mineral species, holubite, ideally Ag₃Pb₆(Sb₈Bi₃)_Σ11S₂₄, has been found at Kutná Hora ore district, Czech Republic. The mineral is associated with other lillianite homologues (gustavite, terrywallaceite, vikingite and treasurite) most frequently as grain aggregates and replacement rims of earlier Ag–Pb–Bi minerals, growing together in aggregates up to 200 × 50 μm. It typically occurs in a close association with Ag,Bi-bearing galena and terrywallaceite. Holubite is opaque, steel-grey in colour and has a metallic lustre, the calculated density is 5.899 g/cm³. In reflected light holubite is greyish white and bireflectance and pleochroism are weak with grey tints. Anisotropy is weak to medium with grey to bluish-grey rotation tints. Internal reflections were not observed. Electron microprobe analyses yielded an empirical formula, based on 44 atoms per formula unit (apfu) of (Ag_3.03Cu_0.03)_Σ3.06(Pb_6.19Fe_0.02Cd_0.01)_Σ6.22(Sb_7.71Bi_2.90)_Σ10.61S_24.12. Its unit-cell parameters are: a = 19.374(4), b = 13.201(3), c = 8.651(2) Å, β = 90.112(18)°, V = 2212.5(9) ų, space group P2₁/n and Z = 2. Holubite is a new member of the andorite branch of the lillianite homologous series with N = 4. The structure of holubite contains two Pb sites with a trigonal prismatic coordination, eight distinct octahedral sites, of which one is a mixed (Bi,Ag) site and one is a mixed (Sb,Pb) site, and twelve anion sites. Holubite is defined as a lillianite homologue with the three following requirements: N = 4, L% [Ag⁺ + (Bi³⁺,Sb³⁺) ↔ 2 Pb²⁺ substitution] ≈ 70% and approximately one quarter to one third at.% of antimony is replaced by bismuth [Bi/(Bi+Sb) ≈ 0.26–34]. The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-112) and named after Milan Holub, a key Czech geologist and specialist in the Kutná Hora ore district.