Halotrichite

A variety of Minerals

Halotrichite specimen - rock identification

What is Halotrichite?

Halotrichite, also known as feather alum, is a highly hydrated sulfate of aluminium and iron. Its chemical formula is FeAl2(SO4)4·22H2O. It forms fibrous monoclinic crystals. The crystals are water-soluble. It is formed by the weathering and decomposition of pyrite commonly near or in volcanic vents. The locations of natural occurrences include: the Atacama Desert, Chile; Dresden in Saxony, Germany; San Juan County, Utah; Iceland and Mont Saint-Hilaire, Canada. The name is from Latin: halotrichum for salt hair which accurately describes the precipitate/evaporite mineral. Gallery

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Halotrichite Localities Map

See where Halotrichite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

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North ZoneCentral RidgeSouth Basin

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More Images

Halotrichite specimen 2
© Robert M. Lavinsky
Halotrichite specimen 3
© Dave Dyet http://www.shutterstone.com http://www.dyet.com

Quick Facts

Physical Properties

Color
Colourless to white, yellowish, greenish; colourless in transmitted light.
Hardness (Mohs)
1.5 - 2
Density
1.95 g/cm³
Streak
White

Chemical Properties

Chemical Formula
FeAl2(SO4)4 · 22H2O
Elements
Al, Fe, H, O, S

Also Known As

HalotrichiteFeather AlumHalotrichumMountain Butter
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