Hexahydrite is a fragile, water-soluble sulfate mineral that typically forms as an efflorescence in arid environments or on the walls of mine workings. It is easily recognized by its fibrous white crusts but must be stored in a dry, sealed container to prevent dehydration and crumbling into a powder.
Is this hexahydrite?
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 hexahydrite with a known reference. Hexahydrite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hexahydrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hexahydrite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, efflorescent crusts, massive.
Often confused with
Hexahydrite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hexahydrite
Minerals reported to co-occur with hexahydrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgSO₄·6H₂O
- Mohs hardness
- 2
- Density
- 1.76 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Efflorescent Crusts, Massive
- Cleavage
- Perfect On {010}
- Rarity
- Common
- Uses
- Collector
- Host rock
- Arid Climate Evaporite Deposits, Mine Dumps
- Typical price
- $10-40 thumbnail specimen
Where rockhounds find hexahydrite
Classic worldwide localities
- Ashcroft, British Columbia, Canada
- Soda Lake, California, USA
- Salzburg, Austria
- Chuquicamata, Chile
Field-hunting tip
Look in arid climate evaporite deposits, mine dumps country — that is the host setting where hexahydrite typically forms. If you start seeing epsomite, gypsum, halite in float, you are in the right ground. Field specimens usually show a fibrous, efflorescent crusts, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hexahydrite?+
Where is hexahydrite found?+
How much is hexahydrite worth?+
What rocks look like hexahydrite?+
What minerals are found with hexahydrite?+
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Find hexahydrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
