Rustumite

rustumite

larnite

merwinite

kilchoanite

Images

Formula: Ca₁₀(Si₂O₇)₂(SiO₄)(OH)₂Cl₂
Sorosilicate (Si₂O₇ groups)
Crystal System: Monoclinic
Specific gravity: 2.94 calculated
Streak: White
Colour: Colourless
Common impurities: H₂O
Environments

Metamorphic environments

Localities

At the type locality, Kilchoan, Ardnamurchan, Fort William and Ardnamurchan, Highland, Scotland, UK, rustumite occurs in a metamorphosed limestone between spurrite dominant and kilchoanite dominant assemblages, formed during a metamorphic period in which H₂O:CO₂ in the vapour phase was relatively high. Associated minerals include åkermanite, merwinite, larnite, spurrite, rankinite and kilchoanite. The rustumite may carry many inclusions of spurrite, melilite or its alteration products, merwinite, larnite, and occasionally rankinite or kilchoanite. Rustumite and tilleyite belong to the same stage of metamorphism (MM 34.1.1-16, HOM, Dana ).

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