Chloraluminite is a rare hydrated aluminum chloride mineral typically found as white, efflorescent crusts or fine crystalline coatings around volcanic fumaroles. Due to its high solubility in water and sensitivity to atmospheric humidity, it is extremely fragile and must be stored in a dry, sealed container to prevent deliquescence.
Is this chloraluminite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch chloraluminite with a known reference. Chloraluminite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chloraluminite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Chloraluminite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: crusts, efflorescent growths.
Often confused with
Chloraluminite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside chloraluminite
Minerals reported to co-occur with chloraluminite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlCl₃·6H₂O
- Mohs hardness
- 2.5
- Density
- 2.32 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Crusts, Efflorescent Growths
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumaroles
- Typical price
- $50-300 per specimen
Where rockhounds find chloraluminite
Classic worldwide localities
- Vesuvius, Italy
- Mount Etna, Italy
- Tolbachik volcano, Russia
Field-hunting tip
Look in fumaroles country — that is the host setting where chloraluminite typically forms. If you start seeing malladrite, hieratite, sal ammoniac in float, you are in the right ground. Field specimens usually show a crusts, efflorescent growths habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chloraluminite?+
Where is chloraluminite found?+
How much is chloraluminite worth?+
What rocks look like chloraluminite?+
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Find chloraluminite on the map
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