Dreyerite is a rare bismuth vanadate mineral that typically forms as small, bright yellow to orange-yellow platy crystals. It is most commonly found as a secondary mineral in the oxidized zones of uranium-vanadium deposits, often associated with other bismuth minerals.
Is this dreyerite?
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 dreyerite with a known reference. Dreyerite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: brownish yellow, orange.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy.
Often confused with
Dreyerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Pucherite is the harder of the two (Mohs 4 vs. 2-3); luster reads adamantine on Dreyerite and vitreous to adamantine on Pucherite.
How to tell apart: Luster reads adamantine on Dreyerite and earthy to subvitreous on Clinobisvanite.
Often found alongside dreyerite
Minerals reported to co-occur with dreyerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiVO₄
- Mohs hardness
- 2-3
- Density
- 6.25 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Adamantine
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Platy
- Cleavage
- Distinct on {111}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In rhyolitic tuffs, intercalated with carbonaceous matter and silicified wood
Where rockhounds find dreyerite
Classic worldwide localities
- Hirschhorn, near Kaiserlautern, Rhineland-Palatinate, Germany
Field-hunting tip
Where it forms: In rhyolitic tuffs, intercalated with carbonaceous matter and silicified wood. If you start seeing bismite, mixite, carnotite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.
Common questions
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Find dreyerite on the map
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