Images
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:
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).
Back to Minerals