Orishchinite, a new terrestrial phosphide, the Ni-dominant analogue of allabogdanite

Sergey N. Britvin, Mikhail N. Murashko, Yevgeny Vapnik, Anatoly N. Zaitsev, Vladimir V. Shilovskikh, Maria G. Krzhizhanovskaya, Liudmila A. Gorelova, Oleg S. Vereshchagin, Evgeny A. Vasilev, Natalia S. Vlasenko

Research output: Contribution to journalArticlepeer-review

Abstract

Orishchinite is a new terrestrial phosphide discovered in pyrometamorphic rocks of the Daba-Siwaqa combustion complex in West Jordan. The mineral occurs as an accessory phase in the fused clinopyroxene-plagioclase rock (paralava) texturally resembling gabbro-dolerite. Orishchinite forms resorbed equant grains up to 0.2 mm outrimmed with 0.1–0.2 thick zones of substituting murashkoite, FeP. Chemical composition (electron microprobe, wt%): Ni 38.49, Fe 22.38, Co 0.47, Mo 18.80, P 19.46, Total 99.60, corresponding to the empirical formula (Ni1.04Fe0.64Mo0.31Co0.01)Σ2.00P on the basis of 3 apfu. The simplified formula is (Ni,Fe,Mo)2P and the ideal one is Ni2P. Macroscopically, orishchinite grains have yellowish-white colour with metallic lustre. The mineral is brittle. In reflected light, orishchinite is yellowish-white and non-pleochroic. It is very weakly anisotropic (ΔR589 = 1.3%). Reflectance values for the wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are [Rmax/Rmin (%), λ (nm)]: 48.1/47.5, 470; 50.6/49.4, 546; 52.1/50.8, 589; 54.4/52.9.1, 650. The crystal structure was solved and refined to R1 = 0.016 based on 224 unique observed [I ≥ 2σ(I)] reflections. Orishchinite is orthorhombic, space group Pnma, a 5.8020(7), b 3.5933(4), c 6.7558(8) Å, V 140.85(3) Å3, Z = 4, Dx = 7.695 g cm-3. The strongest lines of the powder X-ray diffraction pattern [(d, Å) (I, %) (hkl)] are: 2.265(100)(112), 2.201(16)(202), 2.142(55)(211), 2.100(35)(103), 1.909(21)(013), 1.811(19)(113), 1.796(31)(020). Orishchinite is dimorphous with transjordanite (hexagonal Ni2P) and can be considered the Ni-dominant analogue of allabogdanite.

Original languageEnglish
JournalMineralogy and Petrology
DOIs
StateAccepted/In press - 1 Jan 2022

Keywords

  • Crystal structure
  • Gabbro-dolerite
  • Hatrurim formation
  • Jordan
  • Phosphide
  • Pyrometamorphism

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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