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Formula: KFe3+(SO4)2.H2O
Hydrated sulphate
Crystal System: Monoclinic
Specific gravity: 2.84 measured, 2.839 calculated
Hardness: 2½
Streak: White
Colour: Pale lemon yellow, yellowish green, grey; colourless to pale yellow in transmitted light
Luminescence: Not fluorescent under UV
Solubility: Slowly decomposed by water leaving ferric oxide
Environments
Sedimentary environments
Fumeroles
Localities
At Grotta dell'Allume, Faraglione Nico, Faraglioni di Levante, Porto Levante, Vulcano Island, Lipari, Eolie
Islands, Metropolitan City of Messina, Sicily, Italy,
aluminocoquimbite (new in 2009) is formed as a product
of low-temperature (<100°C) fumarolic activity, associated with
alunogen, coquimbite,
krausite, tamarugite,
voltaite, pertlikite,
yavapaiite,
pickeringite and
metavoltine
(CM 48.6.1465–1468).
At the Santa María mine, Velardeña, Velardeña District, Cuencamé Municipality, Durango, Mexico, krausite
is formed on a dump by post-mine oxidation of pyrite. Associated
minerals include copiapite,
voltaite and
halotrichite
(HOM).
At the type locality, Sulphur Hole, Calico, Calico District, Calico Mts, San Bernardino County, California,
USA, krausite is an uncommon secondary mineral
in sulphate-bearing chert. Associated minerals include
alunite, coquimbite,
römerite, voltaite and
metavoltine
(HOM).
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