Woodhouseite

woodhouseite

jarosite

topaz

lazulite

Images

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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