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Formula: NaCa2(Mg3AlTi4+)(Si6Al2)O22O2
Inosilicate (chain silicate), titanium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.2 to 3.28 measured, 3.11 calculated
Hardness: 5 to 6
Streak: Brownish grey
Colour: Dark brown to black
Common impurities: Fe,Mn,K,F,H2O
Environments
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-bearing
augite, rhönite,
olivine, ilmenite,
spinel, plagioclase and
titanium-bearing pargasite
(HOM).
Localities
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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