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Formula: CaAl(PO4)(OH)2.H2O
Hydrated phosphate containing hydroxyl
Crystal System: Orthorhombic
Specific gravity: 2.78 measured, 2.77 calculated
Hardness: 4
Streak: White
Colour: Colourless to snow-white
Solubility:
Environments
Foggite is a secondary phosphate, probably formed at less than 300oC
in complex granite pegmatites
(Webmin, HOM, AM 60.957-964).
Associated minerals include carbonate-rich apatite,
childrenite, whitlockite,
montebrasite, siderite and
quartz
(HOM).
Localities
At the Mount Deverell variscite deposit, Milgun Station, Western Australia, foggite
occurs in variscite veins associated with
crandallite. Some veins of foggite in
variscite have crystals of baryte or
hydroxylapatite at their cores. The variscite
deposits are hosted by marine sedimentary rocks
(AJM 20.2.24).
At the type locality, the Palermo No. 1 Mine, Groton, Grafton county, New Hampshire, USA, foggite occurs in the
whitlockite-apatite paragenesis which derived from
the replacement of triphylite crystals. Associated minerals include
quartz, siderite,
scorzalite, goyazite,
palermoite, bjarebyite,
childrenite and arrojadite. The foggite
forms white foliated plates upon quartz, childrenite
and siderite. In addition, dense masses of quartz and
montebrasite showing sporadic granular scorzalite
often contain cavities lined with quartz crystals and
childrenite, and foggite often occurs on these earlier minerals
(AM 60.957-964).
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