Titre du document / Document title

FINDING OF THE LOW-ALUMINUM NEVADAITE IN THE KARA-CHAGYR AREA, KYRGYZSTAN

Auteur(s) / Author(s)

KARPENKO V. Yu. ; PAUTOV L. A. ; AGAKHANOV A. A. ;

Résumé / Abstract

The rare phosphate ― nevadaite has been found at Kara-Chagyr area (Batken region, Kyrgyzstan) in zone of alteration of vanadium-bearing 'black shales'. The mineral occurs as blue crusts of spherulite aggregates consisting of tiny tabular crystals (0.1―10 μm). It associates with metahewettite, miniyulite, fluellite, hummerite, carnotite, crandallite, variscite woodhauseite. Optical properties: n = 1.542―1.555, D_meas (for aggregates) = = 2.58(1) g/cm³, D_cale =2.582 g/cm³. Most intensive X-ray powder reflections are as follows: [d/n, Å, (I_meas), (hkl)]: 9.54(80)(020), 6.03(100)(200), 5.61(100)(130), 3.91(60)(310), 3.41(80)(041), 2.982(100)(241), 2.804(60)(331), 2.672(70)(061), 1.845(60)(352), 1.507(70)(243). Calculated cell dimensions are: a = = 12.072(10) Å, b = 18.958(15) Å, c = 4.969(5) Å, α = β = γ = 90°, V= 1137.21 ų. Electron microprobe analyses gives (wt %): [observed (average from 8 analyses); those, calc. for 22H₂O)]: P₂O₅ 34.69(31.85), SiO₂ 0.25(0.24), Al₂O, 25.61(23.50), V₂O₃ 5.58(5.13), Fc₂O₃ 0.48(0.46), MnO 0.03(0.03), CuO 10.79(9.90), ZnO 0.69(0.65), CaO 0.18(0.15), MgO 0.17(0.17), K₂O 0.08(0.08), F 7.40(6.79), H₂O 17.16 (by difference) (23.90) ― F₂ = O 3.11(2.86), total 100.00(100.00). Crystal-chemical formula of the mineral: (Cu⁺²_2.2□V⁺³_1.21Al_0.15Zn_0.14 Fe_0.10Mg_0.07Ca_0.05 K_0.03Mn_0.01)_6.00aAl_8.00(P_7.93Si_0.07O₃₂)(OH)_2.98·22(H₂O) for theoretical number of molecular water. Described nevadaite differs form the type location Gold Quarry mineral (Nev., USA) by the lower Al content. IR-spectra, microphotographs of nevadaite and associated minerals are given.

Revue / Journal Title

Zapiski Vserossijskogo mineralogičeskogo obŝestva   ISSN 0869-6055 

Source / Source

2009, vol. 138, n^o1, pp. 83-90 [8 page(s) (article)]

Langue / Language

Russe

Editeur / Publisher

Nauka, Sankt-Peterburg, RUSSIE, FEDERATION DE  (1992) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 4673, 35400018835059.0070