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Formula: Ca2Cu(AsO4)2.2H2O
Hydrated arsenate,
roselite group
Crystal System: Monoclinic
Specific gravity: 3.79 measured, 3.77 calculated
Hardness: 3
Streak: White
Colour: Pale blue, light blue
Luminescence: Not fluorescent under long wave or short wave UV
Solubility: Insoluble in water, acetone and hydrochloric acid
Environments
Volcanic igneous environments
Hydrothermal environments
Localities
At the type locality, the Maria Catalina mine, Pampa Larga mining district, Tierra Amarilla, Copiapó Province,
Atacama, Chile, rruffite is a secondary mineral
found in the oxidation zone of the copper -
arsenic orebody. The vein in which rruffite was found is
hosted in volcaniclastic rocks of Lower Cretaceous age (145 to 100.5 million years ago). This vein, which was
mined for silver, ranges in thickness from 40 to 70 cm and can be
traced for more than 300 metres on the surface. Primary
mineralisation is found only in the lowest parts of the mine, and consists of
pyrite, stibnite,
native arsenic, quartz,
baryte and
ankerite–siderite. The
oxidised portion of the vein largely consists of baryte and
quartz with abundant
mansfieldite. Silver is
present as iodargyrite,
chlorargyrite and
native silver. Other arsenates
found at the property include pharmacoalumite,
arsenolite,
barahonaite-(Al),
betpakdalite,
conichalcite,
lavendulan, talmessite,
philipsbornite and
metazeunerite. Non-arsenate minerals include
wulfenite, duftite and
phosphohedyphane.
Rruffite, on the cotype samples, is found closely associated with
quartz, baryte,
mansfieldite,
pharmacoalumite,
conichalcite,
metazeunerite and
barahonaite-(Al). Rruffite crystals are in granular or
blocky aggregates and druses, with single crystals up to 0.30 x 0.30 x 0.30 mm3
(CM 49.3.877-884).
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