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Z Wiki.Meteoritica.pl

Karwowski Łukasz, Kryza Ryszard, Muszyński Andrzej, Kusz Joachim, Helios Katarzyna, Drożdżewski Piotr, Galuskin Evgeny V., (2016), Czochralskiite, Na₄Ca₃Mg(PO₄)₄, a second new mineral from the Morasko IAB-MG iron meteorite (Poland), European Journal of Mineralogy, 28(5), 2016, s. 969-977 (abstrakt).^[1] Plik doi; plik DjVu

Źródło: Wiki.Meteoritica.pl

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Abstract: Czochralskiite, Na₄Ca₃Mg(PO₄)₄, is the second new phosphate mineral found in the Morasko IAB-MG iron meteorite. This very rare mineral occurs in phosphate inclusions (nodules) with graphite rims enclosed in the kamacite–taenite matrix of the meteorite. Almost thirty mineral species have been reported from this meteorite (most from various inclusions), including six, possibly eight phosphates (fluorapatite, buchwaldite, brianite, merrillite, moraskoite Na₂Mg(PO₄)F,^[2] chlorapatite? and whitlockite?), and schreibersite, chromite, enstatite (‘bronzite’), kosmochlor, kosmochlor–augite, olivine, albite, orthoclase, quartz, cohenite, nickelphosphide, altaite, troilite, pyrrhotite, sphalerite, daubreelite, djerfisherite, and native Cu. Czochralskiite forms xenomorphic, usually oval grains and amoeboid aggregates, between 0.1 and 0.5 mm in size. It is colourless and transparent, with white streak and vitreous lustre; it shows no fluorescence, it is biaxial (+): α = 1.608(2), β = 1.611(2), γ = 1.616(2); α = a, β = b, γ = c; 2V(meas.) = 70°(10), 2V(calc.) = 76°; the dispersion is very weak; Mohs' hardness is 4–5; the fracture is irregular, conchoidal, and no cleavage was observed. The mean of twelve electron-microprobe analyses is (wt%): P₂O₅ 46.28, CaO 27.59, Na₂O 20.04, MgO 6.21, FeO 0.32, MnO 0.16, K₂O 0.09, total 100.69, leading to the empirical formula Na_3.97Ca_3.02Mg_0.95Mn²⁺_0.01K_0.01Fe²⁺_0.03P_4.00O₁₆). The calculated density based on the empirical formula and the single-crystal structural data is 3.148 g · cm⁻³. The structure of czochralskiite [Pnma, a = 17.9230(2), b = 10.7280(2), c = 6.7794(1) Å, V = 1303.53(3) Å³, Z = 4] is of the glaserite-type and related to that of buchwaldite and brianite. The strongest diffraction lines of the calculated czochralskiite powder diffraction pattern are [d _hkl (I)]: 3.802(48), 3.728(31), 2.726(100), 2.679(63), 2.602(83), 1.901(44). The Raman spectrum shows the following characteristic bands (cm⁻¹, strong bands in bold face): 1119, 1167, 1053, 1039, 1022, 1011, 986, 974, 966, 606, 585, 578 and 441. The Raman data show the absence of H₂O and CO₂. Czochralskiite is interpreted as a primary phosphate, which crystallized together with graphite and other phosphates inside the nodules. The mineral name honours Jan Czochralski (1885–1953), Polish chemist, crystallographer and metallurgist.

Keywords: brianite, crystal structure, czochralskiite, glaserite type, iron meteorites, Morasko, new mineral, phosphate, Raman

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