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Formula: Na2(Ti,Fe3+)Si4(O,F)11
Inosilicate (chain silicate)
Crystal System: Tetragonal
Specific gravity: 2.64 to 2.83 measured, 2.81 calculated
Hardness: 7
Streak: White
Colour: Yellow, yellowish-white, greyish-white, honey-yellow, tan, greenish-yellow
Environments
Plutonic igneous environments
Pegmatites
Metamorphic environments
Localities
At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, narsarsukite occurs in
hornfels, igneous breccia and
marble xenoliths in an intrusive alkaline
gabbro-syenite complex
(HOM).
At the type locality, the Narssârssuk pegmatite, Narsaarsuk Plateau, Igaliku, Kujalleq, Greenland, narsarsukite occurs in pegmatite
associated with aegirine, microcline,
albite, elpidite,
epididymite, tainiolite and
quartz
(HOM).
At Sage Creek, Sweet Grass Hills, Liberty county, Montana, USA, narsarsukite occurs in
quartz veins cutting an orthoclase -
albite - aegirine -
quartz hybrid rock in a zone adjacent to a syenite
stock intruding limestone. Pectolite is the
dominant vein mineral, and quartz and narsarsukite are also abundant;
calcite and galena are the remaining
primary minerals in the veins. The paragenetic sequence appears to be
pectolite and narsarsukite oldest, followed by
galena and calcite, with
quartz youngest of all. Minerals associated with narsarsukite include
aegirine, pectolite,
calcite, feldspar,
galena, manganese-bearing pectolite and
quartz (AM 44.265-273, HOM). Fresh material was found at the old prospect pit on one of
the veins, associated with galena, alunite,
epidote, clinozoisite,
apatite and feldspar
(AM 20.598-601)
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