Douglasite is a rare, water-soluble chloride mineral typically found in potash salt mines and salt deposits. It often occurs as colorless to yellowish tabular crystals or crusts that are extremely sensitive to humidity and can easily dehydrate or dissolve if not stored in a controlled environment.
Is this douglasite?
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 douglasite with a known reference. Douglasite 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. Douglasite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Douglasite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellowish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, crusts, or efflorescences.
Often confused with
Douglasite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside douglasite
Minerals reported to co-occur with douglasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂FeCl₄·2H₂O
- Mohs hardness
- 2.5
- Density
- 2.10 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Crusts, Or Efflorescences
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Potash Salt Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find douglasite
Classic worldwide localities
- Westeregeln, Germany
- Stassfurt, Germany
- Carlsbad, New Mexico, USA
Field-hunting tip
Look in potash salt deposits country — that is the host setting where douglasite typically forms. If you start seeing carnallite, sylvite, halite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, or efflorescences habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find douglasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
