Combeite

combeite

gotzite

wollastonite

melilite

Images

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

Volcanic igneous 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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