Halotrichite
A variety of Minerals

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
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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

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