Rasvumite Locality: Rasvuuchorr Mountain, Khibiuy Massif, Kolo, Russia Size: miniature, 3.6 x 3.1 x 2.6 cm Rasvumite (HUGE XL) This specimen features a sharp freestanding rasvumite [possibly djerfisherite, see http://www.mindat.org/mesg-7-75510.html ] on matrix. I am told that , at 6-7mm, this freestanding rasvumite crystal is quite exceptional. 3.6 x 3.1 x 2.6 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Rasvumite
Rasvumite is an IMA-recognized mineral species in the sulfide class, with the chemical formula KFe₂S₃.
It crystallizes in the orthorhombic crystal system (space group Cmcm). It is a member of the Cubanite structural group.
Key properties: specific gravity 3.1; Metallic luster.
IMA symbol Rsv, IMA status: approved, named in 1970.
Typically an alteration product of pyrrhotite; in differentiated alkalic massifs (Russia); in an alkalic mafic diatreme (Coyote Peak, California, USA).
It is found associated with Djerfisherite, chlorbartonite, pyrrhotite, cubanite, potassic feldspar, nepheline, acmite (Russia); pyrrhotite, nepheline, acmite, analcime.
The name refers to its occurrence on Mt. Rasvumchorr, Kola Peninsula, Russia.