Inosilicate (chain silicate)
Specific gravity: 3.2 to 3.28
Hardness: 5 to 6
Streak: Brownish grey
Colour: Dark brown to black
Common impurities: Fe,Mn,K,F,H2O
Kaersutite is common as phenocrysts in alkaline volcanic rocks; in gabbro
and peridotite nodules in alkaline
basalt; in syenite,
monzonite, carbonate tuff
and alkaline gabbro (HOM). Associated minerals include titanium-rich
spinel, plagioclase and
The type locality is Østerfjeld, Qaarsut, Nuussuaq Peninsula, Avannaata, Greenland, Denmark.
At Wart Holm, Orkney Islands, Scotland, United Kingdom, kaersutite occurs in hornblende feldspathoid lamprophyre (Dana).
At Soda Springs vent, San Carlos Indian Reservation, Gila county, Arizona, USA, megacrysts of kaersutite and anorthoclase are common in iron-rich alkaline lava. They contain small inclusions of kaersutite and apatite in anorthoclase, and apatite in kaersutite (AM 65.306-312).
Near Boulder Dam, San Carlos Reservation, Graham county, Arizona, United States, kaersutite occurs as phenocrysts in lamprophyre dikes (Dana).
In the Cripple Creek mining district, Colorado, USA, kaersutite occurs as crystals to 2 mm in plagioclase phonolite and, rarely, in lamprophyre (Min Rec 36-2.173)
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