Tiny dark pink grains of rastsvetaevite in matrix. Field of view 3 mm. Specimen and photo Leon Hupperichs. From: Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia. — Photo: Leon Hupperichs · CC BY-SA 3.0
Rastsvetaevite
A rare eudialyte-group mineral — only the third member with dominant potassium in its structure.
Intro adapted from Wikipedia (CC BY-SA).
Rastsvetaevite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₂₇K₈Ca₁₂Fe₃Zr₆Si₅₂O₁₄₄(OH,O)₆Cl₂.
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Eudialyte structural group.
Key properties: Mohs hardness 5–6; specific gravity 2.86; White streak; Vitreous luster; optically uniaxial.
IMA symbol Rvt, IMA status: approved, named in 2000.
Found in alkaline pegmatite in zоnes of late intense potassium metasomatism.
It is found associated with Nepheline, sodalite, potassium feldspar, aegirine, scherbakovite, villiaumite, natrite, nacaphite, rasvumite, davinciite.
The mineral was named to honor Russian crystallographer Ramiza K. Rastsvetaeva (b. 1936), Institute of Crystallography of the Russian Academy of Sciences, Moscow.