Titre du document / Document title

Ankinovichite - the nickel analogue of alvanite: A new mineral from Kurumsak (Kazakhstan) and Kara-Chagyr (Kyrgyzstan)

Auteur(s) / Author(s)

KARPENKO V. Y. ; PAUTOV L. A. ; SOKOLOVA E. V. ; HAWTHORNE F. G. ; AGAKHANOV A. A. ; DIKAYA T. V. ; BEKENOVA G. K. ;

Résumé / Abstract

Ankinovichite, ideally (Ni,Zn)A14(VO³)²(OH)¹²(H20)2 (mon., sp. gr. P2¹/n, a = 17.8098(8), b = 5.1228(2), c = 8.8665(4) Å, β = 92.141(1)°, V= 808.4(2) Å₃, Z= 2), the nickel analogue of alvanite, is a newly identified mineral from vanadium-bearing schists of the Kara-Tau ridge, Kazakhstan (Kurumsak) and S. Fergana, Kyrgyzstan (Kara-Chagyr). The mineral occurs as tabular elongated crystals, up to 0.5 mm in size, overgrown on alvanite in association with volborthite, goethite and carnotite (Kurumsak), crystal crusts (individuals 0.05-0.2 mm) and V-shape twins (up to 0.1-0.5 mm) in cavities of quartziferous breccia with nickelalumite, kolovratite, volborthite, allophane, metatyuyamunite, roscoelite, gypsum and tangeite (Kara-Chagyr). Cleavage is perfect on (010). Mohs' hardness 2.5-3, microhardness VHN = 68(57-88) kgs/mm₂, D^meas = 2.48(2) g/cm₃, D^calc = 2.476 g/cm₃. Ankinovichite is transparent, bluish light green to colourless, vitreous luster. Biaxial negative, a = 1.653O, β = 1.677(2), γ = 1.706(3), 2V^meas = 86(2)°, 2V^calc = 86°, dispersion strong, r < v. No pleochroism and no fluorescence in ultraviolet light. Microprobe analyses (Kara-Chagyr/ Kurumsak) show (wt %): Al²O³ 33.82/33.79, SiO² 0.59/0.67, V²O⁵ 28.4½7.98, FeO 0.14/0.35, NiO 8.43/7.19, CuO 0.27/0.20, ZnO 2.24/4.20, H²O 23.30 (Penfield method)/25.65 (by difference), total 97.20/100.00. According to empirical formulae, derived from crystal-structure and microprobe analyses, on the basis of 4 Al atoms per formula uhit, the simplified formula is (Ni,Zn)Al4(VO³)²(OH)¹²(H²O)². Structure of the mineral was studied. The strongest powder-diffraction lines [(d/n) (Å); (1/1⁰)(hkI)] are: 8.89(100)(200), 7.83(100)(101), 3.354(40)(012), 3.266(50)(501), 1.970(80)(422), 1.904(70)(-621), 1.680(40)(820), 1.481(80)(-615). Monocrystal study of ankinovichite (Kara-Chagyr) confirmed that it is isostructural with alvanite. The mineral is named after E. A. Ankinovich (1911-1991) and S. G. Ankinovich (1912-1985), prominent investigators of geology and mineralogy of vanadium-bearing schists of Middle Asia and Kazakhstan. Type material is in A. E. Fersman Mineralogical Museum (Moscow).

Revue / Journal Title

Zapiski Vserossijskogo mineralogičeskogo obŝestva   ISSN 0869-6055 

Source / Source

2004, vol. 133, n^o2, pp. 59-70 [12 page(s) (article)]

Langue / Language

Russe

Editeur / Publisher

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

Localisation / Location

INIST-CNRS, Cote INIST : 4673, 35400011431799.0040