Hydrated sulphate containing hydroxyl, copiapite group
Specific gravity: 2.163 calculated
Hardness: 2 to 3
Streak: Light yellow
Colour: Pale lemon-yellow to deep yellow
Solubility: Soluble in water
Aluminocopiapite is a secondary mineral formed by
oxidation of pyrite in coal deposits and
shale; it may also be of fumarolic origin. It is associated with
There are two co-type localities, Mosquito Fork, Forty Mile River, Southeast Fairbanks Census Area, Alaska, USA, and Temple Mountain, San Rafael Mining District, Emery county, Utah, USA.
At Mosquito Fork, Forty Mile River, Southeast Fairbanks Census Area, Alaska, USA, aluminocopiapite occurs as a thin local efflorescence in sheared and crushed bedrock of the river bank near an old prospect pit. The bedrock in the area is probably schist, and appears to include fragments of quartzite and metamorphosed shale. The crushed rock immediately associated with the aluminocopiapite is composed largely of quartz, albite, chlorite, kaolinite and lesser amounts of muscovite and pyrite. The aluminocopiapite occurs as minute, fragile lemon-yellow scales and as earthy blooms covering surfaces in the sheared rocks, and appears to form locally by the oxidation of pyrite (AM 52.1220-1223).
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