Referenza:
▪ Vymazalová, A., Laufek, F., Sluzhenikin, S.F., Stanley, C.J., Kozlov, V.V., Chareev, D.A., Lukashova, M.L. (2017): Kravtsovite, PdAg2S, a new mineral from the Noril’sk-Talnakh deposit, Krasnoyarskiy kray, Russia. European Journal of Mineralogy, 29, 597-602.
Abstract:
Kravtsovite, PdAg2S, is a new platinum-group mineral discovered in the Komsomolsky mine of the Talnakh deposit, Noril’sk district, Russia. It forms equant inclusions (ranging in size from a few μm to 40–50 μm) in silicates and pyrite, commonly intergrown with vysotskite and Au–Ag alloy in aggregates (100–200 μm across) with telargpalite, cooperite, braggite, vysotskite, sopcheite, stibiopalladinite, sobolevskite, moncheite, kotulskite, malyshevite and insizwaite. Kravtsovite is brittle; it has a metallic lustre and a grey streak. In plane-polarised light, kravtsovite is yellowish white, has strong bireflectance, is strongly pleochroic in shades of slightly yellowish white to bluish grey, and exhibits a strong anisotropy with rotation tints of salmon-pink, orange, pale blue and dark blue–black. It exhibits no internal reflections. Reflectance values in air (R1, R2 in %) are: 32.2, 38.3 at 470, 31.6, 39.4 at 546, 30.2, 39.8 at 589 and 28.8, 41.1 at 650 nm. Eighteen electron probe microanalyses of kravtsovite give the average composition: Pd 30.53, Ag 60.11, S 8.47, and Se 0.74, total 99.85 wt%, corresponding to the empirical formula Pd1.03Ag1.99(S0.95Se0.03)Σ0.98 based on a total of 4 atoms per formula unit (apfu). The average of eight analyses on synthetic kravtsovite is: Pd 30.98, Ag 60.27, and S 8.81, total 100.07wt%, corresponding to Pd1.04Ag1.99S0.98. The mineral is orthorhombic, space group Cmcm, with a 7.9835(1), b 5.9265(1), c 5.7451(1)Å, V 271.82(1)Å3 and Z = 4. The crystal structure was refined from the powder X-ray-diffraction data of the synthetic analogue. The strongest lines in the X-ray powder diffraction pattern of synthetic kravtsovite [d in Å (I) (hkl)] are: 2.632(51)(021), 2.458(65)(112), 2.4263(71)(310), 2.3305(60)(202), 2.2352(100)(311), 2.1973(48) (221), 2.0619(42)(022), 1.9172(30)(130), 1.3888(31)(240,332), 1.3586(28)(512). The mineral honours V.F. Kravtsov, one of the discoverers of the Talnakh and Oktyabrsk deposits in the Noril’sk district of Russia.
▪ Vymazalová, A., Laufek, F., Sluzhenikin, S.F., Stanley, C.J., Kozlov, V.V., Chareev, D.A., Lukashova, M.L. (2017): Kravtsovite, PdAg2S, a new mineral from the Noril’sk-Talnakh deposit, Krasnoyarskiy kray, Russia. European Journal of Mineralogy, 29, 597-602.
Abstract:
Kravtsovite, PdAg2S, is a new platinum-group mineral discovered in the Komsomolsky mine of the Talnakh deposit, Noril’sk district, Russia. It forms equant inclusions (ranging in size from a few μm to 40–50 μm) in silicates and pyrite, commonly intergrown with vysotskite and Au–Ag alloy in aggregates (100–200 μm across) with telargpalite, cooperite, braggite, vysotskite, sopcheite, stibiopalladinite, sobolevskite, moncheite, kotulskite, malyshevite and insizwaite. Kravtsovite is brittle; it has a metallic lustre and a grey streak. In plane-polarised light, kravtsovite is yellowish white, has strong bireflectance, is strongly pleochroic in shades of slightly yellowish white to bluish grey, and exhibits a strong anisotropy with rotation tints of salmon-pink, orange, pale blue and dark blue–black. It exhibits no internal reflections. Reflectance values in air (R1, R2 in %) are: 32.2, 38.3 at 470, 31.6, 39.4 at 546, 30.2, 39.8 at 589 and 28.8, 41.1 at 650 nm. Eighteen electron probe microanalyses of kravtsovite give the average composition: Pd 30.53, Ag 60.11, S 8.47, and Se 0.74, total 99.85 wt%, corresponding to the empirical formula Pd1.03Ag1.99(S0.95Se0.03)Σ0.98 based on a total of 4 atoms per formula unit (apfu). The average of eight analyses on synthetic kravtsovite is: Pd 30.98, Ag 60.27, and S 8.81, total 100.07wt%, corresponding to Pd1.04Ag1.99S0.98. The mineral is orthorhombic, space group Cmcm, with a 7.9835(1), b 5.9265(1), c 5.7451(1)Å, V 271.82(1)Å3 and Z = 4. The crystal structure was refined from the powder X-ray-diffraction data of the synthetic analogue. The strongest lines in the X-ray powder diffraction pattern of synthetic kravtsovite [d in Å (I) (hkl)] are: 2.632(51)(021), 2.458(65)(112), 2.4263(71)(310), 2.3305(60)(202), 2.2352(100)(311), 2.1973(48) (221), 2.0619(42)(022), 1.9172(30)(130), 1.3888(31)(240,332), 1.3586(28)(512). The mineral honours V.F. Kravtsov, one of the discoverers of the Talnakh and Oktyabrsk deposits in the Noril’sk district of Russia.