Rosenbuschite from the khibiny alkaline massif

摘要

Rosenbuschite occurs in Khibiny massifwithin pegmatites and fenitized xenoliths innepheline syenites. It forms there light-brown andorange-yellow aggregates of acicular and thinflattened prismatic crystals and associates withmicrocline, nepheline,sodalite, aegirine,astrophyllite, lavenite, zircon, biotite and ilmenite.Crystals of the mineral are transparent, with vitreousluster. Cleavage is clear on (100). Hardness 5-6,brittle, conhoidal fracture. Observed density is3.34(4). Microprobe analysis, X-ray powderdiffraction data and IR-spectrum of the mineral arepresented in the paper. It should be remarked thatbefore this finding rosenbuschite have been known inrussia with certainty within Lovozero massif only.