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
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Halotrichite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
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Quick Facts
Physical Properties
- Color
- Colourless to white, yellowish, greenish; colourless in transmitted light.
- Hardness (Mohs)
- 1.5 - 2
- Rock tumbling
- Not recommended
- 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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Halotrichite FAQs
How do I identify Halotrichite?
Halotrichite can be identified by its hardness of 1.5 - 2 on the Mohs scale, Colourless to white color. Look for these key characteristics when examining specimens.
What color is Halotrichite?
Halotrichite typically appears in Colourless to white, yellowish, greenish; colourless in transmitted light.. Color can vary depending on impurities and formation conditions.
How hard is Halotrichite?
Halotrichite has a hardness of 1.5 - 2 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
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