Cotype material of stibiogoldfieldite from the Mohawk mine, Goldfield, Nevada, USA, has been examined in order to collect single-crystal X-ray diffraction data of Te-rich stibiogoldfieldite and to characterise the associated Ag–Bi–(S,Se) phase. Tellurium-rich stibiogoldfieldite, with empirical formula (Cu11.30Ag0.03)Σ11.33(Sb0.80As0.57Bi0.06Te2.57)Σ4.00(S12.83Se0.20)Σ13.03, is cubic, space group I$\bar{4}$3m, with unit-cell parameters a = 10.2947(3) Å and V = 1091.04(10) Å3. Its crystal structure has been refined to R1 = 0.0161 for 397 unique reflections with Fo > 4σ(Fo) and 25 refined parameters. The structure refinement confirmed the occurrence of a vacancy at the M(2) site, in agreement with the substitution M(2)Cu+ + X(3)(Sb/As)3+ = M(2)□ + X(3)Te4+. The Ag–Bi–(S,Se) phase was identified as the 6P homologue of the pavonite series, namely dantopaite. Its empirical formula is Cu1.36Ag4.39Pb0.12Bi12.62Sb0.06(S14.01Se7.91Te0.08), showing an exceptionally high Se content. Unit-cell parameters of Se-bearing dantopaite are a = 13.518(2), b = 4.0898(6), c = 18.984(3) Å, β = 106.816(6)°, V = 1004.7(3) Å3 and space group C2/m. The crystal structure was refined to R1 = 0.0504 for 1230 unique reflections with Fo > 4σ(Fo) and 82 refined parameters. The metal excess (~0.55 atoms per formula unit) of this pavonite homologue is mainly due to the accumulation of Ag and Cu in the thin slab of the crystal structure, whereas the high Se content is related to the partial replacement of S occurring preferentially in the thick PbS-like slab. Domains richer in Se and Pb in dantopaite, with empirical formula Cu0.89Ag4.50Pb0.49Bi12.53Sb0.07(S11.26Se10.74), were also identified, as grains up to 30 μm in size intimately intergrown with bohdanowiczite, indicating the possibility of a wide Se-to-S substitution in dantopaite.

The new mineral tennantite-(Ni), Cu6(Cu4Ni2)As4S13, has been discovered from the Luobusa Chromitite, Tibet, southwestern China. Tennantite-(Ni) occurs as anhedral grains ranging from 2 to 20 μm in size. In reflected light microscopy, tennantite-(Ni) is isotropic and appears yellow-greenish grey. Reflectance data for Commission on Ore Mineralogy wavelengths in air for tennantite-(Ni) are: 31.0 (470 nm), 29.6 (546 nm), 29.6 (589 nm) and 29.3 (650 nm). Electron microprobe analysis for holotype material gave the empirical formula (on basis of total cations = 16 apfu): M(2)Cu6 M(1)[Cu4.00(Ni0.97Cu0.53Fe0.50)Σ2.00]Σ6.00X(3)(As2.94Sb1.06)Σ4S12.77. Tennantite-(Ni) is cubic, with space group I$\bar{ 4}$3m (#217), a =10.2957(9) Å, V = 1091.4(3) Å3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R1 = 0.0423 on the basis of 163 independent reflections [Fo > 4σ (Fo)]. The calculated seven strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are: 2.972 (100) (222), 1.820 (83) (440), 2.574 (28) (400), 1.552 (18) (622), 3.640 (10) (220), 1.880 (10) (521) and 1.287 (7) (800). Tennantite-(Ni) is isostructural with other tetrahedrite-group minerals, and nickel is hosted at the tetrahedrally coordinated M(1) site, along with Cu and minor Fe. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2021-018).

Argentotetrahedrite-(Cd), Ag6(Cu4Cd2)Sb4S13, has been approved as a new mineral species by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association using samples from Rudno nad Hronom, Slovak Republic. It occurs as anhedral grains up to 30 μm in size, steel-grey to black in colour, with a metallic lustre, in association with greenockite and other tetrahedrite-group minerals [argentotetrahedrite-(Zn) and tetrahedrite-(Zn)], earlier base-metal minerals, Ag sulfides and sulfosalts (acanthite, pyrargyrite and polybasite) and later galena. Argentotetrahedrite-(Cd) is isotropic, grey in colour, with a creamy tint and rapidly (tens of minutes) tarnishes to orange–brown. Reflectance data for Commission on Ore Mineralogy (COM) wavelengths in air are [λ (nm), R (%)]: 470, 30.4; 546, 30.3; 589, 30.3; and 650, 28.7. The chemical formula of the samples studied, recalculated on the basis of ΣMe = 16 atoms per formula unit, is: (Ag3.28Cu2.72)Ʃ6.00[Cu4(Cd1.68Fe0.27Zn0.16)]Ʃ6.11(Sb3.71As0.15)Ʃ3.86S12.79. Argentotetrahedrite-(Cd) is cubic, I$\bar{4}$3m, with a = 10.65(2) Å, V = 1208(4) Å3 and Z = 2. Argentotetrahedrite-(Cd) is isotypic with other members of the tetrahedrite group. The structural relationship between argentotetrahedrite-(Cd) and other members of the freibergite series are discussed and previous findings of this species are briefly reviewed.

The new mineral, zvěstovite-(Zn), ideally Ag6(Ag4Zn2)As4S13, was found in quartz–baryte gangue at the mine dump of the abandoned small deposit of Zvěstov, central Bohemia, Czech Republic. Zvěstovite-(Zn) is associated with tennantite-(Zn), tetrahedrite-(Zn), argentotennantite-(Zn), acanthite and supergene azurite and malachite. The new mineral occurs as rare relic anhedral grains rimmed by acanthite, up to 100 μm in size. Zvěstovite-(Zn) is grey, Mohs hardness is ca. 3½–4, in agreement with other members of the tetrahedrite group; the calculated density is 5.16 g.cm–3. In reflected light, zvěstovite-(Zn) is grey with a greenish tint, without bireflectance, pleochroism or anisotropy. Deep red internal reflections are ubiquitous. Reflectance values of zvěstovite-(Zn) in air (R%) are: 28.5 at 470 nm, 26.9 at 546 nm, 25.5 at 589 nm and 23.8 at 650 nm. The empirical formula for zvěstovite-(Zn), based on electron-microprobe analyses (n = 4), is Ag6.27[(Ag3.90Cu0.38)Σ4.28(Zn1.60Fe0.09Cd0.03)Σ1.72]Σ6.00(As2.26Sb1.48)Σ3.74S12.50. The ideal formula is Ag6(Ag4Zn2)As4S13, which requires (in wt.%) Ag 56.01, Zn 6.79, As 15.56 and S 21.64, total 100.00. Zvěstovite-(Zn) is cubic, I$\bar{4}$3m, with unit-cell parameters: a = 10.850(2) Å, V = 1277.3(8) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I) (hkl)] are: 3.1321(100) (222), 2.7125(21) (400), 1.9809(11) (521), 1.9180(31) (440) and 1.6357(15) (622). According to the single-crystal X-ray diffraction data (Robs = 0.051), the crystal structure of zvěstovite-(Zn) agrees with the general features of the members of the tetrahedrite group. Zvěstovite-(Zn) is named after its type locality, Zvěstov; the suffix indicates the dominant divalent C-constituent, according to the approved nomenclature of the tetrahedrite group. It is the As-isotype of rozhdestvenskayaite-(Zn). The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2020-061).

Ore microscope and electron microprobe investigations on Zn-Pb-Ag ores from B Zone in Silvermines, Ireland, have shown the presence of two As-Sb-Ag phases; a tetrahedrite-group mineral with composition Cu6.3Ag3.7Fe0.9Zn1.2As2.2Sb2.1S12.7 and proustite-pyrargyrite (Ag3As0.5Sb0.5S3). It is postulated that both phases inherited their As and Sb from primary geocronite (Pb14.5As3.4Sb2.6S23) and that they are metastable. An enrichment in Ni in the ores is due to very fine to submicroscopic intergrowths of gersdorffite (Ni0.6Fe0.4AsS) with geocronite and with galena.

Hakite, ideally Cu10Hg2Sb4Se13, is a Se-dominant member of the tetrahedrite group occurring at only a few localities in the World. A new occurrence of this mineral in the Příbram uranium and base-metal ore district, Central Bohemia, Czech Republic, is reported in this paper. Hakite was found to be locally abundant and was identified in several samples with Se mineralization. Three chemically distinct types of hakite were distinguished based on electron microprobe study, Hg-rich hakite (hakite sensu stricto), Zn-rich hakite and Cd-rich hakite. Hg-hakite dominates among the samples studied. Its average empirical formula based on 29 apfu (n = 54) is (Cu5.61Ag0.39)∑6.00Cu4.00(Hg1.61Zn0.20Cu0.19Cd0.15Fe0.04)∑2.19(Sb3.85As0.28)∑4.13(Se11.55S1.14)∑12.69 . Less common is the Zn-hakite, (Cu5.80Ag0.20)∑6.00Cu4.00(Zn1.33Hg0.42Cd0.22Cu0.18Fe0.01)∑2.16(Sb3.85As0.26)∑4.11(Se10.92S1.81)∑12.73 (n = 22), and rare Cd-hakite has an empirical formula (n = 7) of (Cu5.84Ag0.16)∑6.00Cu4.00(Cd1.27Zn0.60Cu0.10Hg0.07Fe0.02)∑2.06(Sb4.00As0.19)∑4.19(Se12.14S0.61)∑12.75. The refined unit cell of Hg-hakite from Příbram, obtained from powder X-ray diffraction data, is a = 10.8783(3) Å with V = 1287.3(1) Å3 (Z = 4, for the cubic space group I4̄3m). Structure refinement from the precession electron diffraction data collected on the transmission electron microscope (R = 24.4% for 424 observed reflections), confirmed that hakite is isostructural with tetrahedrite. The evolution of hydrothermal fluids, from which Se mineralization formed, suggests a distinct enrichment in sulfur and depletion in selenium over the time span of crystallization.