Formula: MgAl2(PO4)2(OH)2.8H2O hydrated phosphate with hydroxyl
Specific gravity: 2.319
Hardness: 3½
Streak: White
Colour: Smoky-white, buff, colourless; crystals = pale pink or pale green on tips, colourless in transmitted light
Solubility: Soluble in acids


Hydrothermal environments

Gordonite is a rare secondary mineral formed from the alteration of variscite in nodules in limestone or as a late-stage hydrothermal mineral in complex granitic pegmatites (Mindat).

At the Penrice marble quarry, Angaston, Barossa Valley, Mount Lofty Ranges, South Australia, gordonite crystals have been found scattered on goethite and often perched on minyulite crystals (AJM 17.1.18).

At Tom's quarry, Tom's Quarry, Kapunda, Mount Lofty Ranges, South Australia, gordonite is associated with quartz and also with aldermanite (AJM 17.1.18).

At the Mount Deverell variscite deposit, Milgun Station, Western Australia, gordonite overgrows mitridatite, leucophosphite and foggite, and is post-dated by crandallite and hydroxylapatite. The variscite deposits are hosted by marine sedimentary rocks (AJM 20.2.26).

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