Daubréeite is a rare secondary bismuth halide mineral often occurring as a result of the alteration of bismuth-bearing minerals. It typically presents as soft, pearly crusts or massive aggregates within hydrothermal ore veins. Collectors look for its association with primary bismuth minerals in localities like Bolivia.
Is this daubréeite?
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 daubréeite with a known reference. Daubréeite sits at Mohs 2-2.5, 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: earthy.
- 4Match the color rangeCompare against the expected color range: yellow, yellow brown, cream white.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: compact, earthy, massive.
Often confused with
Daubréeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bismite is the harder of the two (Mohs 4.5 vs. 2-2.5); streak differs, so Daubréeite leaves white, Bismite leaves gray to yellow; luster reads earthy on Daubréeite and subadamantine to dull, earthy on Bismite.
How to tell apart: Streak differs, so Daubréeite leaves white, Bismutite leaves gray; luster reads earthy on Daubréeite and vitreous, waxy, may be dull to earthy on Bismutite.
Often found alongside daubréeite
Minerals reported to co-occur with daubréeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiO(OH)
- Mohs hardness
- 2-2.5
- Density
- 6.4-6.5 g/cm³
- Streak
- White
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Compact, earthy, massive
- Cleavage
- {001}, perfect (by analogy to bismoclite)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by alteration of bismuth or bismuthinite, intermixed with “clay” (Tazna, Bolivia)
Where rockhounds find daubréeite
Classic worldwide localities
- Constancia mine, Tazna, Bolivia
Field-hunting tip
Where it forms: A secondary mineral formed by alteration of bismuth or bismuthinite, intermixed with “clay” (Tazna, Bolivia). If you start seeing kaolinite in float, you are in the right ground. Typical habit: compact, earthy, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find daubréeite on the map
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