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Formula: Na4.5Ca3.5S6O17.5(OH)0.5
Cyclosilicate (ring silicate),
zirsinalite-lovozerite subgroup,
lovozerite group,
Crystal System: Trigonal
Specific gravity: 2.884 measured, 2.79 calculated
Streak: White
Colour: Colourless
Common impurities: Ti,Zr,Al,Fe,Mn,Mg,Zn,Ba,K,F,Cl,S,P
Environments
Localities
At the type locality, Mount Shaheru, Nyiragongo Volcano, Nyiragongo Territory, North Kivu, DR Congo,
combeite
occurs as poorly developed, stout hexagonal prisms, a few tenths of a millimetre in length, in
nephelinite, associated with
götzenite
(MM 31.503-510).
At the Kugda massif, Maimecha and Kotui Rivers Basin, Krasnoyarsk Krai, Russia,
djerfisherite has been found in melt inclusions in
melilite. The inclusion mineral assemblage includes
pyrrhotite, pentlandite,
forsterite, diopside,
monticellite, phlogopite,
wollastonite, nepheline,
sodalite, combeite and
calcite
(MM 63.3.433–438).
At Ol Doinyo Lengai, Ngorongoro District, Arusha region, Tanzania, combeite occurs in
nephelinite and ash ejecta, associated with
wollastonite,
clinopyroxene,
nepheline, melilite,
titanium-bearing garnet and
titanium-bearing magnetite
(HOM).
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