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:
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
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