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Formula: KFe3+(SO4)2.4H2O
Hydrated sulphate
Crystal System: Monoclinic
Specific gravity: 2.43 measured, 2.461 calculated
Hardness: 2½
Streak: White
Colour: Pale yellowish green
Environments
Sedimentary environments
Fumeroles rarely
Localities
At the Santa Bárbara sulphur mine, El Palmar hot springs, Cerros de Santa Bárbara, Santa Bárbara Department, Jujuy
Province, Argentina, the sulphur prospect is hosted by calcareous
sandstone and yellow
limestone. These rocks are argillised (altered to
clay minerals) in the mineralised zone and contain disseminated
sulphur in rhombic crystals, gypsum
in milimetric veinlets and lenses, and a suite of sulphates composed of
voltaite, metavoltine,
hexahydrite, alunogen,
sideronatrite,
ferrinatrite, krausite,
halotrichite and goldichite. This assemblage occurs in
underground works where, at the time of collection, in the floor of one of the workings, two fumarolic vents 10 cm in
diameter were dispersing a CO2-rich vapour phase at a temperature of 40o to 50oC.
The fumarolic vents are surrounded by a soft mass composed of
halotrichite
and alunogen spotted with crystals of
voltaite and krausite. The other
sulphates, including goldichite, occur on the argillised (altered to
clay minerals) rock that forms the walls of the galleries
(CM 33.1059-1062).
At the type locality, the Dexter No. 7 Mine, Calf Mesa Mining District, Emery county, Utah, USA,
shales and mudstones form
a steep slope below a cliff. Directly below the ore horizon, and extending down over the slope, is a talus
breccia composed of fragments of
conglomerate. A trench has been cut into this talus directly below
the workings, and it is here that the sulphates are found cementing the talus fragments. The minerals of this suite,
in addition to goldichite, are coquimbite,
halotrichite, römerite,
alunogen, copiapite,
melanterite, fibroferrite,
voltaite, butlerite,
parabutlerite,
chalcanthite and diadochite.
The essential minerals of the uranium deposit are
metazeunerite, pyrite and
chalcopyrite.
Goldichite occurs as small laths in radiating clusters and as encrustations of minute crystals in the near
surface zone of the talus. It is closely associated with platy masses of white
alunogen, purple crystals of
coquimbite and bright yellow, small crystals of
copiapite
(AM 40.469-480).
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