Meliphanite and leucophanite from the Sakharjok alkaline massif (Kola Peninsula)

Lyalina L. M., Savchenko Ye. E., Kadyrova G. I., Selivanova E. A.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2020. V. 149. N 1. P. 64-75

https://doi.org/10.31857/S0869605520010074

Language: Russian

Abstract

Meliphanite is a widespread mineral in the large nepheline syenite pegmatite and surrounding metasomatites of the Sakharojk alkaline massif, Kola Peninsula. In these rocks, the mineral differs in morphology and chemical composition. It forms late idiomorphic crystals with the high aluminum content in the pegmatite and poikilitic crystals substantially depleting in aluminum but with the higher content of OH-groups in metasomatites. The high sodium content and presence of OH-groups distinguish Sakharjok meliphanite from Norway meliphanite. Leucophanite is a rare mineral in the Sakharjok massif. It was found there only as intergrowths with meliphanite in metasomatites. The chemical composition of leucophanite is stable, with exception of fluorine, and approaching the ideal formula. The reason for the unique paragenesis of meliphanite and leucophanite, previously considered as impossible, is their metasomatic origin.

Keywords: beryllium silicate, meliphanite, leucophanite, electron microprobe analysis, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, Penfield method, nepheline syenite pegmatite, metasomatite, Sakharjok alkaline massif, Kola Peninsula