Kieserite is a common magnesium sulfate mineral found primarily in marine evaporite deposits. It typically occurs as massive, granular, or compact earthy aggregates and is often indistinguishable from other salts without chemical testing or X-ray diffraction.
Is this kieserite?
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 kieserite with a known reference. Kieserite sits at Mohs 3.5, 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: white, colorless, green yellow, gray white, yellowish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Kieserite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Kieserite is noticeably harder (Mohs 3.5 vs. 2-2.5).
How to tell apart: Kieserite is noticeably harder (Mohs 3.5 vs. 1.5-2); luster reads vitreous on Kieserite and subvitreous, pearly on {010} cleavages, silky if fibrous on Gypsum.
How to tell apart: Kieserite is noticeably harder (Mohs 3.5 vs. 2-2.5); luster reads vitreous on Kieserite and pearly to vitreous on Hexahydrite.
Often found alongside kieserite
Minerals reported to co-occur with kieserite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgSO₄·H₂O
- Mohs hardness
- 3.5
- Density
- 2.571 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- On {110}, {111}, perfect; on {111}, {101}, {011}, imperfect
- Rarity
- Common
- Uses
- Industrial, Fertilizer, Collector
- Host rock
- Typically in marine salt deposits; rarely as a volcanic sublimate or efflorescence
Where rockhounds find kieserite
2 mapped spotsClassic worldwide localities
- Carlsbad potash district, Eddy Co., New Mexico, extending into west, Texas, USA
- Paradox Basin, Grand Co., Utah, USA
- Stassfurt-Westeregeln district, Bartensleben mine, Saxony-Anhalt, Germany
- Hildesia mine, near Hannover, and at Wathlingen, Lower Saxony, Germany
- Hallstatt, Austria
- Stebnyk and Kalusz, Ukraine
Field-hunting tip
Where it forms: Typically in marine salt deposits; rarely as a volcanic sublimate or efflorescence. If you start seeing halite, carnallite, polyhalite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada, Utah. Start trip planning there.
Common questions
How do you identify kieserite?+
Where is kieserite found?+
Can I find kieserite in the United States?+
What rocks look like kieserite?+
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Find kieserite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
