Formula: KFe2S3
Specific gravity: 3.1
Hardness: 4½
Colour: Steel-grey
Common impurities: Na,Mg,Ca,Cu


Rasvumite is a rare mineral occurring in pegmatites, typically as an alteration product of pyrrhotite (HOM).

At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, rasvumite occurs in sodalite syenite xenoliths associated with an intrusive alkalic gabbro - syenite complex. Associated minerals include ussingite, villiaumite, sidorenkite and sodalite (HOM).

At Flekkeren, Skien, Telemark, Norway, rasvumite has been found in a contact-metamorphosed xenolith (HOM).

There are two co-type localities, the Kirovskii apatite mine, Kukisvumchorr Mountain, and the Apatitovyi Tsirk, Rasvumchorr Mine, Rasvumchorr Mountain, both in the Khibiny Massif, Murmansk Oblast, Russia. Here rasvumite occurs in pegmatites, in grains, usually less than 1 mm, as aggregates of very fine, often curved needles, commonly along grain boundaries of K-feldspar, nepheline, and aegirine. Other associated minerals include djerfisherite, chlorbartonite, pyrrhotite and cubanite (AM 56.1121-1122, HOM).

At Ol Doinyo Lengai, Ngorongoro District, Arusha region, Tanzania, rasvumite occurs in natrocarbonate lavas (HOM).

At Coyote Peak, Coastal Range, Humboldt county, California, USA, rasvumite occurs in an alkalic mafic diatreme (HOM).

At the Point of Rocks Quarry, Point of Rocks Mesa, Springer, Colfax county, New Mexico, USA, rasvumite is associated with pyrrhotite, nepheline, aegirine, analcime and K-feldspar (HOM).


Rasvumite partially alters to orange-brown FexSy in open air, within days or hours (Mindat).

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