Foshagite

Formula: Ca4(SiO3)3(OH)2
Inosilicate (chain silicate), dimorph of trabzonite
Specific gravity: 2.36
Hardness: 3 when massive
Streak: White
Colour: White
Solubility: Gelatinises with acids
Environments

Metamorphic environments

Foshagite occurs in contact or thermally metamorphosed limestone (Webmin, Dana). It dehydrate at about 700oC (AM 43.1-15).

At the Eddy Creek quarry, Weld River, southeast Tasmania, Australia, foshagite has been found in skarn (AJM 18.1.65).

At the Dupezeh Mountain,Iraq, foshagite has been found in melilite skarn associated with perovskite, grossular, schorlomite, monticellite, wollastonite, phlogopite, spinel, cuspidine, baddeleyite, baghdadite, pyrrhotite, djerfisherite and valleriite (HOM).

At Kilchoan, Scotland, UK, foshagite has been found in thin veins in thermally altered limestone, associated with merwinite, larnite and kilchoanite (HOM).

At the co-type localities, Crestmore quarries, Riverside county, California, USA, foshagite occurs in thin veins in thermally altered limestone associated with hillebrandite, calcite, vesuvianite, garnet and thaumasite (HOM, Dana).

Common impurities: Al,Fe,Mg

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