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TitleKurilite - Ag8Te3Se - a new mineral from the Prasolovskoe deposit, Kuril islands, Russian Federation
AuthorKovalenker, V A; Plotinskaya, O Y U; Stanley, C J; Roberts, A CORCID logo; McDonald, A M; Cooper, M A
SourceMineralogical Magazine vol. 74, no. 3, 2010 p. 463-468,
Alt SeriesEarth Sciences Sector, Contribution Series 20110153
PublisherMineralogical Society
Mediapaper; on-line; digital
File formatpdf
AreaKuril islands; Russian Federation
Subjectsmineralogy; optical properties; mineral occurrences; mineral specimens; analytical methods; x-ray diffraction; powder diffraction; crystallography; pegmatites; electron microscope analyses; Prasolovskoe deposit
Illustrationstables; graphs
Released2018 07 05
AbstractKurilite, with the simplified formula, Ag8Te3Se, 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/mm2 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 (Ag7.97Au0.02)?7.99Te3.00(Se0.86Te0.12S0.03)?1.01. The calculated density is 7.799 g/cm3 (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) Å, V 4231(12)Å3, c:a 1.2386, Z = 15. Its crystal structure remains unsolved. The seven strongest lines of the X-ray powder-diffraction pattern [d in Å(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.

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