Aluminocopiapite

aluminocopiapite

pyrite

chlorite

albite

Images

Formula: (Al,Mg)Fe3+4(SO4)6(OH,O)2.20H2O
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
Environments

Sedimentary environments
Hydrothermal environments
Fumeroles

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 pyrite (HOM).

Localities

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).

Back to Minerals