Crandallite

minerals

fluellite

gordonite

montgomeryite

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Formula: CaAl3(PO4)(PO3OH)(OH)6
Hydrated phosphate containing hydroxyl
Specific gravity: 2.92
Hardness: 5
Streak: White
Colour: Yellow, white, gray; colourless in transmitted light.
Solubility: Soluble with difficulty in acids.
Common impurities: Sr and Ba substituting for Ca and Fe3+ for Al (Dana).
Environments:

Pegmatites
Sedimentary environments
Hydrothermal environments

Crandallite is a secondary mineral that occurs in iron-rich, silica-poor phosphate deposits and as an alteration product in pegmatites (Dana). It may be found as a pseudomorph after gordonite (Dana).

Localities

In the phosphate deposits of South Australia crandallite is found as a replacement of other phosphate minerals, notably wavellite, also apatite, fluellite and minyulite (AJM 17.1.14).

At the Mount Deverell variscite deposit, Milgun Station, Western Australia, crandallite is a common alteration product of variscite; it crystallised late in the paragenetic sequence, and occurs as inclusions in hydroxylapatite. The variscite deposits are hosted by marine sedimentary rocks (AJM 20.2.24).

At the Bone Valley Formation, Florida, USA, crandallite is associated with clay, millisite and wavellite (Dana).

At the Brooklyn Mine, Utah, USA, crandallite is associated with quartz and baryte (Dana).

At Fairfield, Utah, USA, crandallite is associated with millisite, wardite, variscite, gordonite, englishite, montgomeryite, overite, kolbeckite and apatite (Dana).

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