Argentotetrahedrite-(Cd), Ag₆(Cu₄Cd₂)Sb₄S₁₃, a new member of the tetrahedrite group from Rudno nad Hronom, Slovakia.

Abstract

Argentotetrahedrite-(Cd), Ag6(Cu4Cd2)Sb4S13, has been approved as a new mineral species by the International Mineralogical Association -Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC) 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), tetrahedrite-(Zn)), earlier base metal minerals, Ag sulfides and sulfosalts (acanthite, pyrargyrite, polybasite) and later stage galena. Argentotetrahedrite-(Cd) is isotropic, grey in colour, with a creamy tint, rapidly (tens of minutes) tarnished to orangebrown. Reflectance data for COM wavelengths in air are [λ (nm), R (%)]: 470, 30.4; 546, 30.3; 589, 30.3; and 650, 28.7. Chemical formula of the samples studied, recalculated on the basis of ΣMe = 16 apfu (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-43m, with a = 10.65(2) Å, V = 1208(4) Å 3 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.

Tetrahedrite-(Cd), Cu6(Cu4Cd2)Sb4S13, from Radětice near Příbram, Czech Republic: the new Cd member of the tetrahedrite group

“…The tetrahedrally coordinated M(1) site has an average Me-S distance of 2.391 Å (Table 6), longer than that observed in mixed (Cu,Zn,Fe) tetrahedrally coordinated sites in tetrahedrite-group minerals (e.g. 2.342 Å - Wuensch, 1964;2.337 Å -Wuensch et al, 1966) and comparable to those observed in tennantite-(Cd) (2.370 Å - Biagioni et al, 2022a) and in argentotetrahedrite-(Cd) (2.38 Å - Mikuš et al, 2023). On the basis of the electron microprobe data, the occu- ).…”

“…In addition to tetrahedrite-(Cd), two other species are represented by the As-isotype tennantite-(Cd) and the Ag-isotype argentotetrahedrite-(Cd). The former was described from the Cd-rich hydrothermal veins of the Berenguela district, Bolivia (Biagioni et al, 2022a), whereas the latter is a very recent addition to the freibergite series and was reported from the Au-Ag epithermal deposits of Rudno nad Hronom, Slovakia (Mikuš et al, 2023). Finally, the selenide hakite-(Cd) was reported from Příbram, central Bohemia, Czech Republic (Škácha et al, 2016Sejkora et al, 2022).…”

“…Currently, six members of the tetrahedrite series have been reported: tetrahedrite-(Fe), tetrahedrite-(Zn), tetrahedrite-(Hg), tetrahedrite-(Mn), tetrahedrite-(Ni), and tetrahedrite-(Cu) (Biagioni et al, 2020a, b;Momma et al, 2022;Wang et al, 2023;Sejkora et al, 2023). Tetrahedrite-(Cd) is a further addition to this series.…”

“…The Cd-bearing tetrahedrite-group minerals are generally rare, but some Cd-dominant chemical compositions have been reported previously (see a brief review below). Recently, three Cd-dominant members of the tetrahedrite group were defined: tennantite-(Cd) from Berenguela, Bolivia (Biagioni et al, 2022a); hakite-(Cd) from Příbram, Czech Republic (Sejkora et al, 2022); and argentotetrahedrite- (Cd) from Rudno nad Hronom, Slovakia (Mikuš et al, 2023). A systematic investigation of tetrahedrite-group minerals from the Příbram uranium and base-metal ore district led to the recognition of a new potential Cd member of the tetrahedrite series.…”

Zipserite, a new bismuth chalcogenide Bi5(S,Se)4 from Nagybörzsöny in Hungary with a R$\bar{3}$m(00γ)00 modulated structure

“…The modulated crystal structure can be rationalized and compared to other chemically related phases in the bismuth-sulfide system. The new mineral, zipserite, and its symbol zps were approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-075, Majzlan et al, 2022).…”