Sodium-rich phosphate and silicate inclusions in the troilite nodule of the Darinskoe iron meteorite (IIC)

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Marco E. Ciriotti
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Sodium-rich phosphate and silicate inclusions in the troilite nodule of the Darinskoe iron meteorite (IIC)

Messaggio da Marco E. Ciriotti » lun 09 gen, 2023 12:03

Referenza:
▪ Sharygin, V.V. (2022): Sodium-Rich Phosphate and Silicate Inclusions in the Troilite Nodule of the Darinskoe Iron Meteorite (IIC). Geochemistry International, 60, 1221-1236.

Abstract:
Sodium-rich phosphate and silicate melt inclusions as well as chromite and schreibersite grains have been studied in the troilite nodule of the Darinskoe IIC iron meteorite. Sulfide association (K-sulfides, pentlandite, chalcopyrite, cubanite ?) commonly occurs around the inclusions. Many phosphate inclusions are altered and represented now by unidentified hydrated Сa–Fe–Mn–Mg-phosphates, which are the replacement products of unhydrated high-Na orthophosphates. Buchwaldite NaCa(PO4) was only found as primary phase of the inclusions; and monetite CaH(PO4) was determined among secondary phosphates. Silicate inclusions contain glass, sometimes Fe-rich serpentine (?), and phosphate. Silicate glasses have highly siliceous and high-Na alkaline composition (SiO2—60.8–74.4 wt %, Na2O + K2O—13.9–16.8 wt %), and are enriched in TiO2 (2.2–11.2 wt %) and Cr2O3 (1.5–3.4 wt %) and virtually free in Al2O3 (<0.2 wt %). It is suggested that the inclusions represent the latest crystallization products of the Darinskoe meteorite formed due to silicate–natrophosphate liquid immiscibility in a sulfide melt. The chemical compositions of the key meteorite minerals, as well as data on rare and potentially new minerals (Cl-free djerfisherite, “Cu-djerfisherite” K7(Cu,Fe)25S26, NiTe, Ni3Fe2, Os–Ir–Pt-rich Fe–Ni alloys, czochralskiite) are also given in the paper. Raman spectra for buchwaldite and monetite are presented.
Marco E. Ciriotti

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