IMA 2012-071 = muraskoite

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Marco E. Ciriotti
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IMA 2012-071 = muraskoite

Messaggio da Marco E. Ciriotti » ven 16 nov, 2018 12:59

Prossima pubblicazione.

▪ Britvin, S.N., Vapnik, Y., Polekhovsky, Y.S., Krivovichev, S.V., Krzhizhanovskaya, M.G., Gorelova, L.A., Vereshchagin, O.S., Shilovskikh, V.V. (2018): Murashkoite, FeP, a new terrestrial phosphide from pyrometamorphic rocks of the Hatrurim Formation, South Levant. Mineralogy and Petrology, 112, (in press).

Murashkoite, FeP, is a new mineral found in pyrometamorphic rocks of the Hatrurim Formation, South Levant. It is a typical accessory phase in the marbles and paralavas in the southern Negev Desert, Israel and on the Transjordan Plateau, Jordan. Murashkoite occurs as grains and aggregates up to 2 mm closely associated with barringerite, (Fe,Ni)2P, and zuktamrurite, FeP2. The rock-forming minerals include pyroxenes of the diopside-hedenbergite series, anorthite with subordinate gehlenite, tridymite, cristobalite, pyrrhotite, fluorapatite, chromite, magnetite, hematite, merrillite and late hydrothermal carbonates, silicates and sulfates. Macroscopically, murashkoite is yellowish-grey in colour and has a metallic lustre. In reflected light, the mineral is white with a beige tint and it is non-pleochroic. The anisotropy is distinct, from yellow-grey to greyish-blue. Selected reflectance values [Rmax–Rmin, % (λ, nm)] are: 42.7–40.8 (400), 42.0–40.6 (500), 44.5–43.4 (600), 48.0–47.7 (700). It is brittle. VHN20 = 468 kg mm−2. The holotype material has the chemical composition (electron microprobe): Fe 63.82; Ni 0.88; P 35.56; total 100.26 wt.%. The empirical formula calculated on the basis of 2 apfu is (Fe0.99Ni0.01)1.00P1.00 corresponding to FeP. Murashkoite is orthorhombic, space group Pnma, unit cell parameters refined from the single-crystal data are: a 5.099(2), b 3.251(2), c 5.695(2) Å, V 94.41(8) Å3, Z = 4, Dx = 6.108(5) g cm−3. The crystal structure was solved and refined to R1 = 0.0305 on the basis of 131 unique reflections with I > 2σ(I). The strongest lines of the powder X-ray diffraction pattern [(d, Å) (I, %) (hkl)]: 2.831(75)(002,011); 2.548(22)(200); 2.477(46)(102,111); 1.975(47)(112); 1.895(100)(202,211); 1.779(19)(103); 1.632(45)(013,301,020). The mineral is named in honour of Dr. Mikhail Nikolaevich Murashko (born 1952), for his contributions to the mineralogy of the Hatrurim Formation. Murashkoite is a natural counterpart of synthetic FeP, the compound widely used in heterogeneous catalysis and electrocatalysis.
Marco E. Ciriotti

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