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Formula: Cu6Ce(PO4)3(OH)6.3H2O
Valence: Cu2+6Ce3+(PO4)3(OH)6.3H2O
Hydrated phosphate, mixite group,
cerium- and copper- bearing mineral
Crystal system: Hexagonal
Specific gravity: 3.424 calculated for the empirical formula
Hardness: 3½
Streak: White
Colour: Yellowish green
Environments
Plutonic igneous environments
Hydrothermal environments
Localities
At the type locality, the Cherry Creek Mining District, Black Hills, Yavapai County, Arizona, USA,
petersite-(Ce) occurs as a rare secondary mineral in
highly weathered granite of an unnamed prospecting pit. Mined for
gold and silver in the early 1900’s,
veins of milky quartz with a small amount of
tourmaline run through this area of the shattered, oxidised
granite. Associated minerals include
malachite, chlorite, a
biotite phase, quartz,
albite, orthoclase,
hematite, chalcopyrite and a
hisingerite-like phase.
Petersite-(Ce) forms in radial clusters of acicular crystals (approximately 20 x 20 x 50 microns3).
It is yellowish green, translucent, and has a white streak and vitreous lustre
(CM 54.6.1505-1511).
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