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Formula: CaAl3(SO4)(PO4)(OH)6
Compound phosphate, beudantite group,
alunite supergroup, forms a series with
svanbergite
Crystal System: Trigonal
Specific gravity: 3.01 measured, 3.00 calculated
Hardness: 4½
Streak: White
Colour: White, flesh-pink, colourless
Solubility: Soluble in acids only after driving off the water in a closed tube (Mindat)
Environments
Hydrothermal environments
Cave deposits
Woodhouseite occurs as a secondary mineral found where
sulphatic argillic (clay-rich) wall rock alteration occurred in
hydrothermal and disseminated ore deposits; rare in cave deposits
(Mindat).
Localities
At the type locality, the Champion mine, White Mountain Peak, White Mountains, Mono county, California, USA,
woodhouseite is a late hydrothermal mineral lining vugs in quartz veins
that cross andalusite zones. It is commonly associated with
topaz, quartz,
augelite, lazulite,
tourmaline, baryte,
muscovite and pyrophyllite,
all of which formed previously to it. Small crystals frequently coat euhedral
quartz and
augelite.
A few interesting specimens have been found showing clear, pseudo-cubic woodhouseite crystals strung like beads
upon hair-like crystals of colourless tourmaline (achroite). In the
portions of veins
that are open to supergene solutions, woodhouseite is
usually
coated with the supergene minerals
jarosite and limonite, and
sometimes with
hyalite opal. Woodhouseite is found only near masses of
lazulite.
Strontium-bearing natroalunite,
which
is also present in the andalusite deposits, is more abundant than
woodhouseite, but natroalunite and woodhouseite have not
been
observed together
(AM 22.939-948).
At the Summitville Mining District, Rio Grande county, Colorado, USA, woodhouseite is a product of sulphatic
argillic (clay-rich) wall-rock alteration in hydrothermal vein and
disseminated
ore deposits, replacing apatite
(HOM).
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