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, 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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What is hydrohalite used for?+
Find hydrohalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
