Hydrohalite is a rare, unstable hydrated form of common table salt that forms only at temperatures below 0.1°C. Because it dehydrates rapidly into halite when exposed to room temperature, collectors must store specimens in hermetically sealed containers kept in freezing conditions.
Is this hydrohalite?
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 hydrohalite with a known reference. Hydrohalite 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. Hydrohalite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hydrohalite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: equant crystals, crusts, or efflorescences.
Often confused with
Hydrohalite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hydrohalite
Minerals reported to co-occur with hydrohalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCl·2H₂O
- Mohs hardness
- 2
- Density
- 1.58 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Equant Crystals, Crusts, Or Efflorescences
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find hydrohalite
Classic worldwide localities
- Great Salt Lake, Utah, USA
- Death Valley, California, USA
- Bodenmais, Germany
- Siberia, Russia
Field-hunting tip
Look in evaporite deposits country — that is the host setting where hydrohalite typically forms. If you start seeing halite, mirabilite, gypsum in float, you are in the right ground. Field specimens usually show a equant crystals, crusts, or efflorescences habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydrohalite?+
Where is hydrohalite found?+
How much is hydrohalite worth?+
What rocks look like hydrohalite?+
What minerals are found with hydrohalite?+
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Find hydrohalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
