Sodium-Rich Phosphate and Silicate Inclusions in the Troilite Nodule of the Darinskoe Iron Meteorite (IIC)

— 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(PO 4 ) was only found as primary phase of the inclusions; and monetite CaH(PO 4 ) 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 (SiO 2 —60.8–74.4 wt %, Na 2 O + K 2 O—13.9–16.8 wt %), and are enriched in TiO 2 (2.2–11.2 wt %) and Cr 2 O 3 (1.5–3.4 wt %) and virtually free in Al 2 O 3 (