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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brown red, light green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
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
- 2.16 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a halite–potash deposit
Where rockhounds find douglasite
Classic worldwide localities
- Douglashall mine, near Westeregeln, northwest of Stassfurt, 34 km south of Magdeburg, Saxony-Anhalt, Germany
Field-hunting tip
Where it forms: In a halite–potash deposit. If you start seeing carnallite, sylvite, halite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify douglasite?+
Where is douglasite found?+
What rocks look like douglasite?+
What minerals are found with douglasite?+
What kind of rock does douglasite form in?+
What is douglasite used for?+
Find douglasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
