Variscite

phosphate

wavellite

Formula: Al(PO4).2H2O
Hydrated normal phosphate, variscite group
Specific gravity: 2.57
Hardness: 4½
Streak: White
Colour: Pale to emerald-green, bluish green, colourless to white, pale shades of brown or yellow, rarely red; Colourless to pale green in transmitted light.
Solubility: Insoluble in hydrochloric acid. Soluble in alkalis.
Environments:

Hydrothermal environments

Variscite is typically deposited under surface conditions in cavities or breccias when phosphatic meteoric waters act on aluminous rocks. Associated minerals include wavellite, crandallite, metavariscite, apatite and quartz in the form of chalcedony (Dana).

The rare secondary mineral gordonite is sometimes formed from the alteration of variscite in nodules in limestone. (Dana).

At the phosphate deposits of the Mount Lofty ranges, South Australia, although uncommon, variscite has been found in several associations. At the Moculta quarry it is associated with opal and jarosite, and in cavities lined with apatite and associated with wavellite, beraunite and cyrilovite. It has also been found associated with cacoxenite, leucophosphite and pyrite, and with wavellite and minyulite.
At Tom's quarry variscite is associated with fluellite, leucophosphite, cacoxenite, wavellite and meurigite-Na in goethite-rich rocks. It has been found perched on minyulite and coating fluorapatite, fluellite and minyulite. In one part of the quarry nodules of variscite have been collected in a mudstone containing mica, tourmaline and rutile, and the variscite is partially altered to crandallite and associated with leucophosphite and childrenite.
At the Fairview workings variscite is associated with fluellite and at St John's quarry with leucophosphite and cacoxenite (AJM 17.1.26 ).

Common impurities: Fe,As

Back to Minerals