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Formula: Fe2+Fe3+4(SO4)6(OH)2.20H2O
Hydrated sulphate containing hydroxyl, copiapite group
Crystal System: Triclinic
Specific gravity: 2.08 to 2.17 measured 2.118 calculated
Hardness: 2½ to 3
Streak: Pale yellow
Colour: Crystals are sulphur-yellow to orange, massive material is greenish-yellow to olive-green.
Solubility: Readily soluble in water
Common impurities: Cu,Ca,Al
Environments
Copiapite is a secondary sulphate formed typically by the weathering and
oxidation of pyrite in a wide range of rock types, preserved in arid climates and rarely associated
with fumarolic action (HOM). Associated minerals include melanterite,
alunogen, fibroferrite,
halotrichite, botryogen,
butlerite and amarantite
(HOM, AM 58.314).
Localities
At the type locality, Copiapó Province, Atacama, Chile, copiapite occurs with melanterite,
fibroferrite, alunogen,
halotrichite and other sulphates
(Dana).
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