Publication Type:Journal Article
Source:Mineralogical Magazine, Mineralogical Society, London, United Kingdom, Volume 74, Number 3, p.463-468 (2010)
Keywords:Asia, Commonwealth of Independent States, crystal chemistry, crystal structure, electron probe data, epithermal processes, formula, Gold, hardness, hessite, Kunashir Island, Kuril islands, lattice parameters, metals, mineral deposits, genesis, mineralization, new minerals, physical properties, Russian Far East, Russian Federation, Russian Pacific region, Sakhalin Russian Federation, selenides, silver, sulfantimonites, sulfosalts, sylvanite, tellurides, tetrahedrite, x-ray diffraction data
Kurilite, with the simplified formula, Ag (sub 8) Te (sub 3) Se, is a new mineral from the Prasolovskoe epithermal Au-Ag deposit, Kunashir Island, Kuril arc, Russian Federation. It occurs as aggregates up to 2 mm in size, composed of brittle xenomorphic grains, up to several mu m in size, in quartz, associated with tetrahedrite, hessite, sylvanite and petzite. Kurilite is opaque, grey, with a metallic lustre and a black streak. Under plane-polarized light, kurilite is white with no observed bireflectance, cleavage, or parting observed. Under crossed polars it appears isotropic without internal reflections. Reflectance values in air and in oil, are tabulated. It has a mean VHN (25 g load) of 99.9 kg/mm (super 2) which equates roughly to a Mohs hardness of 3. Electron microprobe analyses yield a mean composition of Ag 63.71, Au 0.29, Te 29.48, Se 5.04, S 0.07, total 98.71 wt.%. The empirical formula (based on 12 atoms) is (Ag (sub 7.97) Au (sub 0.02) ) (sub Sigma 7.99) Te (sub 3.00) (Se (sub 0.86) Te (sub 0.12) S (sub 0.03) ) (sub Sigma 1.01) . The calculated density is 7.799 g/cm (super 3) (based on the empirical formula and unit-cell parameters refined from single-crystal data). Kurilite is rhombohedral, R3 or R3, a 15.80(1), c 19.57(6) Aa, V 4231(12) Aa (super 3) , c:a 1.2386, Z=15. Its crystal structure remains unsolved. The seven strongest lines of the X-ray powder-diffraction pattern [d in Aa (I)(hkl)] are: 3.727(20)(131), 2.996(50)(232), 2.510(30)(226,422), 2.201(100)(128,416,342), 2.152(20)(603), 2.079(30)(253), 2.046(20)(336,434). The mineral is named after the locality.
GeoRef, Copyright 2018, American Geological Institute.<br/>2010-068332<br/>kurilite<br/>petzite<br/>Prasolovskoye Deposit