Trébeurdenite is a rare member of the hydrotalcite group characterized by its platy, pseudo-hexagonal crystal habit and distinct green color. It is typically found as a secondary mineral in altered metamorphic environments, often requiring microscopic study for positive identification.
Is this trébeurdenite?
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 trébeurdenite with a known reference. Trébeurdenite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Trébeurdenite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Trébeurdenite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green, pale green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, pseudo-hexagonal.
Often confused with
Trébeurdenite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside trébeurdenite
Minerals reported to co-occur with trébeurdenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂Mg₆(OH)₁₆CO₃·4H₂O
- Mohs hardness
- 2
- Density
- 2.16 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Pseudo-hexagonal
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphic Rocks
- Typical price
- $20-100 per specimen
Where rockhounds find trébeurdenite
Classic worldwide localities
- Trébeurden, Brittany, France
- various hydrothermal occurrences
Field-hunting tip
Look in hydrothermal veins in metamorphic rocks country — that is the host setting where trébeurdenite typically forms. If you start seeing goethite, magnesite, serpentine in float, you are in the right ground. Field specimens usually show a platy crystals, pseudo-hexagonal habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify trébeurdenite?+
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What rocks look like trébeurdenite?+
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Find trébeurdenite on the map
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