Wermlandite is a rare layered double hydroxide mineral typically found as small, thin, yellow-to-pale greenish grayish platy crystals. It is primarily known from the historic manganese mines of Långban, Sweden, where it forms in the metamorphic mineral assemblages. Collectors should look for its characteristic pearly luster and perfect basal cleavage, though it is often found as tiny inclusions or crusts on other manganese-bearing minerals.
Is this wermlandite?
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 wermlandite with a known reference. Wermlandite sits at Mohs 1.5, 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: pearly.
- 4Match the color rangeCompare against the expected color range: bluish, greenish gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: hexagonal, platy, thin.
Often confused with
Wermlandite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside wermlandite
Minerals reported to co-occur with wermlandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₇Al₂(OH)₁₈[Ca(H₂O)₆](SO₄)₂·6H₂O
- Mohs hardness
- 1.5
- Density
- 1.932 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Trigonal
- Crystal habit
- Hexagonal, platy, thin
- Cleavage
- On {0001}, perfect, micaceous
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare in a metamorphosed Fe–Mn orebody in a low-temperature fissure-filling assemblage among large calcite crystals
Where rockhounds find wermlandite
Classic worldwide localities
- Långban, Värmland, Sweden
Field-hunting tip
Where it forms: Very rare in a metamorphosed Fe–Mn orebody in a low-temperature fissure-filling assemblage among large calcite crystals. If you start seeing calcite, magnetite in float, you are in the right ground. Typical habit: hexagonal, platy, thin. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wermlandite?+
Where is wermlandite found?+
What rocks look like wermlandite?+
What minerals are found with wermlandite?+
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Find wermlandite on the map
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