Tschermigite is a rare ammonium aluminum sulfate that typically forms as a white efflorescent crust or small octahedral crystals near burning coal seams. It is highly soluble in water and must be kept in a cool, dry environment to prevent dehydration and breakdown of the specimen.
Is this tschermigite?
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 tschermigite with a known reference. Tschermigite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tschermigite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Tschermigite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals, fibrous crusts, or efflorescent masses.
Often confused with
Tschermigite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside tschermigite
Minerals reported to co-occur with tschermigite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)Al(SO₄)₂·12H₂O
- Mohs hardness
- 1.5-2
- Density
- 1.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals, Fibrous Crusts, Or Efflorescent Masses
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Associated with Burning Coal Seams and Carbonaceous Shales
- Typical price
- $20-100 per specimen depending on crystal size
Where rockhounds find tschermigite
1 mapped spotsClassic worldwide localities
- Tschermig, Czech Republic
- Baker County, Oregon, USA
- Hunan Province, China
- Kyzyl-Kum, Uzbekistan
Field-hunting tip
Look in associated with burning coal seams and carbonaceous shales country — that is the host setting where tschermigite typically forms. If you start seeing jarosite, gypsum, sulfur in float, you are in the right ground. Field specimens usually show a octahedral crystals, fibrous crusts, or efflorescent masses habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming — start trip planning there.
Common questions
How do you identify tschermigite?+
Where is tschermigite found?+
Can I find tschermigite in the United States?+
How much is tschermigite worth?+
What rocks look like tschermigite?+
What minerals are found with tschermigite?+
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Find tschermigite on the map
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