Carnallite is a soft, deliquescent halide mineral primarily found in marine evaporite deposits. It often appears as massive or granular aggregates that dissolve easily in water and should be stored in a dry environment to prevent degradation.
Is this carnallite?
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 carnallite with a known reference. Carnallite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy, shining.
- 4Match the color rangeCompare against the expected color range: white, blue, colorless, yellow, red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, massive, pseudo hexagonal.
Often confused with
Carnallite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside carnallite
Minerals reported to co-occur with carnallite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KMgCl₃·6H₂O
- Mohs hardness
- 2.5
- Density
- 1.602 g/cm³
- Streak
- White
- Luster
- Greasy, shining
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, massive, pseudo hexagonal
- Cleavage
- None
- Rarity
- Common
- Uses
- Industrial, Collector
- Host rock
- Thought to form in saline marine deposits by reaction of pre-existing saline minerals with fluids high in potash
Where rockhounds find carnallite
4 mapped spotsClassic worldwide localities
- Permian salt basin of southeastern New Mexico, in the Carlsbad potash district, Eddy Co., and adjacent parts, Texas, USA
- Paradox basin, Grand Co., Utah, USA
- Leopoldshall and Westeregeln, near Stassfurt, Magdeburg district, Germany
- Kalusz, Ukraine
- Maman, Azerbaijan
- Barcelona and Lerida Provinces, Spain
Field-hunting tip
Where it forms: Thought to form in saline marine deposits by reaction of pre-existing saline minerals with fluids high in potash. If you start seeing kieserite, sylvite, halite in float, you are in the right ground. Typical habit: fibrous, massive, pseudo hexagonal. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Nevada. Start trip planning there.
Common questions
How do you identify carnallite?+
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Can I find carnallite in the United States?+
What rocks look like carnallite?+
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Find carnallite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
