Abstract
Tsygankoite, ideally Mn8Tl8Hg2(Sb21Pb2Tl)Σ24S48, is a new sulfosalt discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. It occurs as lath-like elongated crystals up to 0.2 mm embedded in calcite–dolomite–clinochlore matrix. The associated minerals also include aktashite, alabandite, arsenopyrite, barite, cinnabar, fluorapatite, orpiment, pyrite, realgar, routhierite, sphalerite, tilasite, and titanite. The new mineral is non-fluorescent, black, and opaque with a metallic lustre and black streak. It is brittle with an uneven fracture and no obvious parting and cleavage. Its Vickers hardness (VHN10) is 144 kg/mm2 (range 131–167 kg/mm2) and its calculated density is 5.450 g cm. In reflected light, tsygankoite is white; between crossed polars it is dark grey to black. It is strongly anisotropic: rotation tints vary from light grey to dark grey to black. Pleochroism and internal reflections are not observed. The chemical composition of tsygankoite (wt %, electron-microprobe data) is: Mn 6.29, Hg 5.42, Tl 26.05, Pb 5.84, As 3.39, Sb 30.89, S 21.87, total 99.75. The empirical formula, calculated on the basis of 90 atoms pfu, is: Mn8.06Tl8.00Hg1.90(Sb17.87As3.19Pb1.99Tl0.97)Σ24.02S48.03. Tsygankoite is monoclinic, space group C2/m, a = 21.362(4) Å, b = 3.8579(10) Å, c = 27.135(4) Å, β = 106.944(14)°, V = 2139.19(17) Å3 and Z = 1. The five strongest diffraction peaks from X-ray powder pattern (listed as (d,Å(I)(hkl)) are: 3.587(100)(112), 3.353(70)(−114), 3.204(88)(405), 2.841(72)(−513), and 2.786(99)(−514). The crystal structure of tsygankoite was refined from single-crystal X-ray diffraction data to R = 0.0607 and consists of an alternation of two thick layer-like arrays, one based on PbS-archetype and the second on SnS-archetype. Tsygankoite has been approved by the IMA-CNMNC under the number 2017-088. It is named for Mikhail V. Tsyganko, a mineral collector from Severouralsk, Northern Urals, Russia, who collected the samples where the new mineral was discovered.
Highlights
The actively exploited Vorontsovskoe gold deposit in Northern Urals, Russia, to the famous Lengenbach deposit in Switzerland or Allchar in Macedonia, was found to be the remarkableMinerals 2018, 8, 218; doi:10.3390/min8050218 www.mdpi.com/journal/mineralsMinerals 2018, 8, 218 source of a interesting Tl–Hg mineralization
Besides several very rare minerals—such as bernardite, chabournéite, christite, dalnegroite, hutchinsonite, imhofite, parapierrotite, picotpaulite, sicherite, vrbaite, etc.—this deposit yielded three new Tl-bearing minerals already approved by IMA-CNMNC with few other potentially new species still being under investigation
We describe the new mineral tsygankoite [pronouncing: tsi gan ko ait] while vorontsovite and ferrovorontsovite are described in another paper of the same special issue
Summary
The actively exploited Vorontsovskoe gold deposit in Northern Urals, Russia, to the famous Lengenbach deposit in Switzerland or Allchar in Macedonia, was found to be the remarkable. Tsygankoite is named for Mikhail Vladimirovitch Tsyganko (born 25 October 1979), a mineral collector from Severouralsk, Sverdlovskaya Oblast’, Northern Urals, Russia. His extensive mineral collection is oriented mostly to the minerals of Northern and Subpolar Urals as well as systematic species served as a base for mineralogical museum “Shtufnoi Kabinet” (Mineral Cabinet), which was founded in 2014 by Mikhail and his friends. Two other new species from the same deposit (vorontsovite and ferrovorontsovite) were collected by him Both the mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association, under the number 2017-088. The type specimen is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia under the registration number 5018/1
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