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The classification of the tetrahedrite group minerals in keeping with the current IMA-accepted nomenclature rules is discussed. Tetrahedrite isotypes are cubic, with space group symmetry I4̄3̄m. The general structural formula of minerals belonging to this group can be written as M(2)A6M(1)(B4C2)X(3)D4S(1)Y12S(2)Z, where A=Cu+, Ag+, [](vacancy), and (Ag6)4+ clusters; B=Cu+, and Ag+; C=Zn2+, Fe2+, Hg2+, Cd2+, Mn2+, Cu2+, Cu+, and Fe3+; D=Sb3+, As3+, Bi3+, and Te4+; Y=S2- and Se2-; and Z=S2-, Se2-, and []. The occurrence of both Me+ and Me2+ cations at the M(1) site, in a 4:2 atomic ratio, is a case of valency-imposed double site-occupancy. Consequently, different combinations of B and C constituents should be regarded as separate mineral species. The tetrahedrite group is divided into five different series on the basis of the A, B, D, and Y constituents, i.e., the tetrahedrite, tennantite, freibergite, hakite, and giraudite series. The nature of the dominant C constituent (the so-called \"charge-compensating constituent\") is made explicit using a hyphenated suffix between parentheses. Rozhdestvenskayaite, arsenofreibergite, and goldfieldite could be the names of three other series. Eleven minerals belonging to the tetrahedrite group are considered as valid species: argentotennantite-(Zn), argentotetrahedrite-(Fe), kenoargentotetrahedrite-(Fe), giraudite-(Zn), goldfieldite, hakite-(Hg), rozhdestvenskayaite-(Zn), tennantite-(Fe), tennantite-(Zn), tetrahedrite-(Fe), and tetrahedrite-(Zn). Furthermore, annivite is formally discredited. Minerals corresponding to different end-member compositions should be approved as new mineral species by the IMA-CNMNC following the submission of regular proposals. The nomenclature and classification system of the tetrahedrite group, approved by the IMA-CNMNC, allows the full description of the chemical variability of the tetrahedrite minerals and it is able to convey important chemical information not only to mineralogists but also to ore geologists and industry professionals.

Tetrahedrite-(Cu), Cu12Sb4S13, has been approved as a new mineral species (IMA2022-078) from the Bankov magnesite deposit near Kosice, Slovak Republic where it occurs as anhedral grains, up to 0.4 mm across, associated with skinnerite, chalcostibite, famatinite, tetrahedrite-(Fe) and zoned aggregates of tennantite-(Cu) to tennantite-(Fe). Tetrahedrite-(Cu) is steel-grey, with a metallic lustre. Mohs hardness is ca. 3 1/2-4 and calculated density is 5.029 g·cm-3. In reflected light, tetrahedrite-(Cu) is isotropic and grey with a bluish shade. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 31.1; 546: 30.1; 589: 29.9; and 650: 28.1. The empirical formula, based on electron-microprobe data (mean of 17 spot analyses), is Cu11.42Zn0.26Fe0.19(Sb4.06As0.08)Σ4.14S12.99. The ideal formula is Cu6(Cu4Cu2)Sb4S13, which requires (in wt.%) Cu 45.76, Sb 29.23 and S 25.01, total 100.00. Tetrahedrite-(Cu) is cubic, I4̄3m, with unit-cell parameters a = 10.3296(15) Å, V = 1102.2(5) Å3 and Z = 2. Its crystal structure was refined by single-crystal X-ray diffraction data to a final R1 = 0.0347 on the basis of 261 unique reflections with Fo > 4σ(Fo) and 22 refined parameters. Tetrahedrite-(Cu) is isotypic with other tetrahedrite-group minerals. Previous findings of tetrahedrite-(Cu) are reported and some nomenclature issues, related to the Fe and Cu oxidation states, are discussed. At the Bankov deposit, tetrahedrite-(Cu) is related to hydrothermal, most probably Alpine, solutions strongly enriched in Cu, Sb and S.

Fahlore crystals and aggregates from the Darasun gold deposit show complex rhythmic-oscillatory chemical zoning resulting from crystal growth and coupled dissolution-reprecipitation reactions. Formation temperatures of these zonal fahlores were determined using the Raabe & Sack (1984) geothermometer and results of ~2780 microprobe analyses. Fahlore is a nearly complete solid solution between tetrahedrite-(Zn) and tennantite-(Fe) with ratios of Sb/(Sb + As) of 0.02–0.85 and Fe/(Fe + Zn) of 0.15–1.00, and exhibits a negative interdependence between these ratios consistent with the thermochemical incompatibility of As and Zn in fahlores. Fahlore compositions in the deposit exhibit scale invariance. The crystallization temperatures for zonal growth crystals of tennantite-(Fe) are from 115 to 314°C, vary from grain to grain and from rhythm to rhythm in individual grains, are similar to those for zonal-heterogeneous fahlore aggregates, from 115 to 290°C, and are in agreement with temperatures obtained for fahlores using fahlore-sphalerite (177–395°C) and fahlore-bournonite-seligmannite (117–316°C) geothermometers, with all of these temperatures being lower than the 284–395°C homogenization temperatures of fluid inclusions in coexisting quartz. Although overlapping in temperatures the general sequence of fahlores precipitated with decreasing temperature was: tetrahedrite + sphalerite → tennantite + sphalerite → fahlore + bournonite-seligmannite → zoned tennantite-(Fe) grains → pseudomorphic zonal-heterogeneous fahlore aggregates. The reasonable temperatures suggest that oscillatory zoning was created at nearly constant temperature and Fe(Zn) –1 exchange potential. About 30–40% of the temperatures are considered to be unreasonable, because the successive layers in oscillatory zoned fahlores were far from osmotic Fe(Zn) –1 exchange equilibrium with each other and/or were not deposited at nearly constant temperature. Using fahlore as an example, it was established that oscillatory zoning in minerals can occur under isothermal conditions under conditions far from equilibrium. The formation of zoning even within the same grain can be caused by different processes. Fahlore is a natural dynamic self-organizing system with a critical point: its composition evolves spontaneously with slight fluctuations in system external parameters with the formation of oscillatory zoning.

Annivite-(Zn), Cu6(Cu4Zn2)Σ6Bi4S13, is a new IMA-approved mineral species from the Geister vein, Jáchymov ore district, Czech Republic. It occurs as anhedral grains, up to 50 µm in size, and growth zones, up to 100 µm in thickness, hosted by oscillatory zoned annivite-(Zn)/tennantite-(Zn) grains, and associated with Bi-rich tennantite-(Zn), tennantite-(Fe), tetrahedrite-(Zn), the not-yet approved 'annivite-(Fe)', bismuth, emplectite, wittichenite and supergene bismite, walpurgite and metazeunerite. In reflected light, annivite-(Zn) is isotropic, pale grey with a brownish shade and very rare pale brown internal reflections. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 32.3; 546: 32.0; 589: 32.0; 650: 31.6. Electron microprobe analysis gave (in wt.% - average of 5 spot analyses): Cu 36.29, Ag 0.14, Fe 0.08, Zn 7.11, Pb 0.19, As 6.07, Sb 4.50, Bi 21.08, S 23.68, total 99.14. On the basis of ΣMe =16 atoms per formula unit, the empirical formula of annivite-(Zn) is Cu10.13Ag0.02Zn1.93Fe0.03Pb0.02Bi1.79As1.43Sb0.66S13.10. Annivite-(Zn) is cubic, I4̄3m, with unit-cell parameters a = 10.3545(6) Å, V = 1110.16(19) Å3 and Z = 2. Its crystal structure was refined by single-crystal X-ray diffraction data to a final R1 = 0.0493 on the basis of 278 unique reflections with Fo > 4σ(Fo) and 23 refined parameters. Annivite-(Zn) is isotypic with other tetrahedrite-group minerals. Its crystal chemistry is discussed, and previous findings of Bi-rich tetrahedrite-group minerals are briefly reviewed, along with the description of a second finding of annivite-(Zn) from the abandoned Mauritius tin mine, Hrebecná, Krusné hory Mountains, Czech Republic.

The new mineral tennantite-(Ni), Cu 6 (Cu 4 Ni 2 )As 4 S 13 , 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) Cu 6 M (1) [Cu 4.00 (Ni 0.97 Cu 0.53 Fe 0.50 ) Σ2.00 ] Σ6.00 X (3) (As 2.94 Sb 1.06 ) Σ4 S 12.77 . Tennantite-(Ni) is cubic, with space group I$\\bar{ 4}$3 m (#217), a =10.2957(9) Å, V = 1091.4(3) Å 3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R 1 = 0.0423 on the basis of 163 independent reflections [ F o > 4σ ( F o )]. 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).

Hakite-(Cd), hakite-(Fe) and hakite-(Zn) are new minerals belonging to the tetrahedrite group and forming, along with hakite-(Hg), the hakite series. They have been discovered in samples collected from the Bytíz deposit, in the uranium and base-metal Príbram ore district, Central Bohemia, Czech Republic. They occur as anhedral grains, up to 300 µm in size, in a calcite gangue, associated with clausthalite, cadmoselite, hakite-(Hg) [for hakite-(Cd)], berzelianite, bukovite, bytízite, crookesite, chaméanite, eskebornite, príbramite, the not yet approved giraudite-(Hg) and giraudite-(Cu), hakite-(Hg), umangite, chalcopyrite, tetrahedrite-(Zn) and a new Cu-As selenide [for hakite-(Fe) and -(Zn)]. The three new species are black, with a metallic lustre. Mohs hardness is ca. 3 1/2-4; calculated density is 6.019 (Hak-Cd), 6.011 (Hak-Fe) and 6.081 g·cm-3 (Hak-Zn). In reflected light, they are isotropic, pale grey with bluish (Hak-Cd) or brownish (Hak-Fe and Hak-Zn) shades. Empirical formulae of hakite-(Cd), hakite-(Fe), and hakite-(Zn) are Cu9.71Ag0.24Cd1.51Hg0.43Zn0.03(Sb3.94As0.13)Σ4.07Se11.35S1.5 7, Cu10.11Ag0.18Fe0.81Zn0.50Hg0.26(Sb3.72As0.41)Σ4.13Se12.65S0. 12, and Cu10.03Ag0.24Zn0.61Fe0.53Hg0.45(Sb3.55As0.60)Σ4.15Se12.82S0. 08, respectively. These formulae correspond to the end-member formulae Cu6(Cu4Cd2)Sb4Se13 (Hak-Cd), Cu6(Cu4Fe2)Sb4Se13 (Hak-Fe), and Cu6(Cu4Zn2)Sb4Se13 (Hak-Zn). All these new members of the hakite series are cubic, I4̄3m, Z = 2, with unit-cell parameters a = 10.8860(6) Å, V = 1290.0(2) Å3 (Hak-Cd); a = 10.7983(4) Å, V = 1259.12(14) Å3 (Hak-Fe); and a = 10.8116(14) Å, V = 1263.8(5) Å3 (Hak-Zn). These species are isotypic with the other members of the tetrahedrite group, and their crystal structures have been refined on the basis of single-crystal X-ray diffraction data down to R1 values of 0.0230 (Hak-Cd), 0.0254 (Hak-Fe), and 0.0302 (Hak-Zn). These structural data allow us to describe the S-to-Se partitioning in hakite-series minerals and to understand the mechanisms avoiding too short Me-Se distances in these selenides.

Thermoelectric materials have considerable potential in the mitigation of the global energy crisis, through their ability to convert heat into electricity. This study aims to valorize natural resources, and potentially reduce production costs, by incorporating tetrahedrite–tennantite (td) ores from the Portuguese Iberian Pyrite Belt into synthetic samples. The ore samples were collected in a mine waste at Barrigão and as “dirty-copper” pockets of ore from the Neves Corvo mine. Subsequently, high-energy ball milling and hot pressing were employed in the production of thermoelectric materials. These are characterized by XRD, SEM/EDS, and thermoelectrical properties. The complete dissolution of the dump material sulfides with the synthetic tetrahedrite constituents led to an increase in the amount of the tetrahedrite–tennantite phase, which was made up of a tetrahedrite–tennantite–(Fe) solid solution. The thermoelectric characterization of these materials is provided, revealing that most of the combined synthetic ore samples displayed better results than the pristine tetrahedrite, mostly due to higher Seebeck coefficient values. Furthermore, the best thermoelectric performance is achieved with 10% of ore, where a power factor of 268 µW.K−2.m−1 is reached at room temperature.

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 (S12.8 3Se0.20)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.

Tetrahedrite-(Cd), Cu 10 Cd 2 Sb 4 S 13 , is a member of the tetrahedrite series of the tetrahedrite group with a predominance of Cd at the C position typically occupied by divalent metals. Cadmium end-members from the tetrahedrite group are rare: they have been described in 15 deposits and ore occurrences. This work reports on a new discovery site of Ag-bearing tetrahedrite-(Cd) at the Kon-Dara mineral deposit (Southwestern Pamirs, Tajikistan) and summarizes the known data on rare Cd-bearing fahlores with a Cd content from 1 to 12.31 wt %. Ag-bearing tetrahedrite-(Cd) at the Kon-Dara deposit occurs as xenomorphic segregations 10–35 μm in size in association with tetrahedrite-(Fe), tetrahedrite-(Zn), galena, polybasite, and chalcopyrite, calculated which replace bournonite. According to the EPMA data, its composition averaged over seven analyses (in wt %) is as follow: Ag 16.17, Cu 25.19, Cd 10.09, Fe 0.38, Zn 0.09, Pb 0.13, Sb 25.55, As 0.18, and S 22.34. The empirical formula calculated based on 29 atoms per unit is (Cu 7.40 Ag 2.80 ) Σ10.20 (Cd 1.68 Fe 0.13 Zn 0.03 Pb 0.01 ) Σ1.84 (Sb 3.92 As 0.04 ) Σ3.96 S 13.00 . The composition of the tetrahedrite-(Cd) from Kon-Dara is similar to those from the Tyndrum Pb–Zn mineralization in Scotland, the Clara baryte–fluorite–(Ag,Cu) mine in Germany, and the Xitieshan Pb–Zn deposit in China. The formation temperature of Ag-bearing tetrahedrite-(Cd) at the Kon-Dara deposit is estimated to have been at about (170–140) ± 20°C.

The legacy of copper (Cu) mining at Spania Dolina-Piesky and Lubietova-Svatodusna (central Slovakia) is waste rock and soil, surface waters, and groundwaters contaminated with antimony (Sb), arsenic (As), Cu, and other metals. Copper ore is hosted in chalcopyrite (CuFeS2) and sulfosalt solid-solution tetrahedrite-tennantite {Cu6[Cu4(Fe,Zn)2]Sb4S13-Cu6[Cu4(Fe,Zn)2]As4S13} that show wide-spread oxidation characteristic by olive-green color secondary minerals. Tetrahedrite-tennantite can be a significant source of As and Sb contamination. Synchrotron-based µ-XRD, µ-XRF, and µ-XANES combined with electron microprobe analyses have been used to determine the mineralogy, chemical composition, element distribution, and Sb speciation in tetrahedrite-tennantite oxidation products in waste rock. Our results show that the mobility of Sb is limited by the formation of oxidation products such as tripuhyite and romeite group mineral containing 36.54 wt% Sb for samples where the primary mineral chemical composition is close to tetrahedrite end-member. Antimony K-edge µ-XANES spectra of these oxidation products indicate that the predominant Sb oxidation state is 5+ Arsenic and Cu are also hosted by amorphous phases containing 6.23 wt% Sb on average and these are intergrown with tripuhyite and romeite. Antimony in this environment is not very mobile, meaning it is not easily released from solid phases to water, especially compared to As, Cu, and S. For samples where the primary sulfosalt is close to tennantite composition, the oxidation products associated with tennantite relicts contain 2.43 wt% Sb and are amorphous. The variable solubility of the secondary minerals that have been identified is expected to influence mobility of Sb and As in near-surface environment.