Abstract:Two new mineral species, vorontsovite, ideally (Hg 5 Cu)TlAs 4 S 12 , and ferrovorontsovite, ideally (Fe 5 Cu)TlAs 4 S 12 , the Tl-and Tl-Fe-analogues of galkhaite, respectively, have been discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. They occur as anhedral grains up to 0.5 mm (vorontsovite) and 0.2 mm (ferrovorontsovite) embedded in a calcite-dolomite matrix. Σ4.00 S 12.00 . Both minerals are cubic, space group I-43m, with a = 10.2956(6) Å, V = 1091.3(1) Å 3 , Z = 2 (vorontsovite); and a = 10.2390(7) Å, V = 1073.43(22) Å 3 , Z = 2 (ferrovorontsovite). The crystal structures of both minerals were refined to R = 0.0376 (vorontsovite) and R = 0.0576 (ferrovorontsovite). Vorontsovite and ferrovorontsovite have been approved by the IMA-CNMNC under the numbers 2016-076 and 2017-007, respectively. The first one is named after the type locality, but also honors the mining engineer Vladimir Vasilyevich Vorontsov. The second is named for its chemical composition, as the Fe-analogue of the first. Both species are isostructural with galkhaite, being its Tl-and Tl-Fe analogues, respectively, and forming altogether the galkhaite group.

This work is the frst paper in a series of publications dedicated to mineralogy of the Vorontsovskoe gold deposit in the Northern Urals. The deposit is unique for both Russia and world with regard to the diversity and originality of Tl–Hg–Mn–As–Sb–S mineralization. Based on available literature and our data, we compiled an exhaustive list of 209 mineral species of the deposit, including eight new minerals found by the authors: vorontsovite, ferrovorontsovite, tsygankoite, gladkovskyite, luborzakite, pokhodyashinite, gungerite and auerbakhite. In addition, 40 and 89 minerals are found for the frst time in Russia and the deposit, respectively. Systematic studies of ores revealed nine main mineral assemblages, seven of which are confned to carbonate breccias. They contain more than 70 rare sulfdes, tellurides and sulfosalts including 30, 12 and 9 minerals, where Tl, Hg and Mn are species-defning elements, respectively. In this paper, we characterize the history of study of the deposit, its geological position and structure, ore types, mineral assemblages, and analytical methods.

The Vorontsovskoe gold deposit (Northern Urals) is unique in both Russia and the world because of the diverse and original Tl–Hg–Mn–As–Sb–S mineralization. Based on the available literature and our data, we present a list of 210 minerals found at this deposit. Eight of them are new minerals discovered by the authors: vorontsovite, ferrovorontsovite, tsygankoite, gladkovskyite, luboržákite, pokhodyashinite, gungerite, and auerbakhite. In addition, 41 minerals are found for the frst time in the Russian Federation and 89 minerals are new for the deposit. We defned nine major ore mineral assemblages, including seven ones related to carbonate breccias. They contain more than 70 rare sulfdes, tellurides and sulfosalts, including 31, 12, and 9 minerals with Tl, Hg and Mn, respectively, as species-defning elements. The paper also describes these mineral assemblages and minerals of the Vorontsovskoe deposit. Keywords: Vorontsovskoe deposit, Northern Urals, ore mineral assemblage, carbonate breccia, Tl-Hg-Mn sulfosalt, new mineral, frst fnd in Russia.

Gungerite, TlAs 5 Sb 4 S 13 , is a new mineral from the Vorontsovskoye gold deposit in Northern Urals. It occurs in limestone breccias composed of calcite and dolomite, and cemented by orpiment, pyrite, realgar, stibnite, and minor baryte and quartz. It belongs to the latest phases among sulfosalts (chiefly Tl-As-Sb ones) present in the ore. The empirical formula (based on the sum of all atoms = 23 pfu) is Tl 0.99 As 5.

The paper continues a series of publications devoted to the mineralogy of the Vorontsovskoe gold deposit in the Northern Urals (Kasatkin et al., 2020). The paper reports on native elements, sulfdes, arsenides and tellurides discovered at the deposit, their chemical compositions, as well as unitcell parameters and optical properties of some minerals. Getchellite, duranusite, pararealgar and picotpaulite are found for the frst time in Russia.