Formula: Ca4MgAl4(PO4)6(OH)4.12H2O hydrated phosphate with hydroxyl, montgomeryite group
Specific gravity: 2.530
Colour: Dark green to light green, colourless, red, yellow
Montgomeryite is a secondary mineral in sedimentary phosphate nodules and a
late-stage mineral in highly oxidized
phosphate nodules in granitic pegmatites (Mindat).
At the Mount Deverell variscite deposit, Milgun Station, Western Australia, montgomeryite occurs coating cavities in variscite veins. The variscite deposits are hosted by marine sedimentary rocks (AJM 20.2.27).
At the Little Green Monster Mine, Utah, USA, montgomeryite is associated with wardite, englishite, gordonite, crandallite and apatite (Dana).
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