Rasvumite

rasvumite

ussingite

villiaumite

pyrrhotite

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Formula: KFe2S3
Sulphide
Crystal System: Orthorhombic
Specific gravity: 3.1 measured, 3.029 calculated
Hardness: 4½
Colour: Steel-grey
Solubility:
Common impurities: Na,Mg,Ca,Cu
Environments:

Pegmatites
Carbonatites

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). This is the world's only active carbonatite volcano, with extremely alkali-rich lava, 30% Na2O (Mindat).

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).

Alteration

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

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