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Formula: Ca4(SiO3)3(OH)2
Inosilicate (chain silicate), paramorph of
trabzonite
Specific gravity: 2.36
Hardness: 3 when massive
Streak: White
Colour: White
Solubility: Gelatinises with acids
Common impurities: Al,Fe,Mg
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, 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 two co-type localities at the 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).
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