Formula: CaAl(PO4)(OH)2.H2O
Hydrated phosphate containing hydroxyl
Specific gravity: 2.78
Hardness: 4
Streak: White
Colour: Colourless to snow-white


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).


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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