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Formula: (Fe,Cu)(SO4).5H2O
Hydrated sulphate, chalcanthite group
Crystal System: Triclinic
Specific gravity: 2.1 to 2.2
Hardness: 2½
Streak: White
Colour: Yellowish, white, light green; colourless in transmitted light
Environments:
Siderotil is a rare supergene mineral formed by
the oxidation of iron sulphides or the dehydration of cuprian melanterite
(MW). It tends to occur in association with other supergene
sulphates such as jarosite. It can be a product of
post-mining oxidation.
Localities
At the type locality, the Idria Mine, Idrija, Slovenia, siderotil is associated with
melanterite
(Mindat).
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