Oswaldpeetersite is a rare uranyl carbonate mineral typically found as delicate, vibrant yellow lath-like crystals. It is primarily known from the Musonoi Mine in the Congo and is highly sought after by collectors specializing in secondary uranium minerals due to its intense fluorescence under UV light.
Is this oswaldpeetersite?
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 oswaldpeetersite with a known reference. Oswaldpeetersite 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. Oswaldpeetersite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Oswaldpeetersite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular to lath-like crystals.
Often confused with
Oswaldpeetersite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside oswaldpeetersite
Minerals reported to co-occur with oswaldpeetersite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (UO₂)₂CO₃(OH)₂·4H₂O
- Mohs hardness
- 2
- Density
- 4.15 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular to Lath-like Crystals
- Cleavage
- Perfect On {001}
- Fluorescence
- Bright Green Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-bearing Hydrothermal Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find oswaldpeetersite
Classic worldwide localities
- Musonoi Mine, Democratic Republic of the Congo
Field-hunting tip
Look in oxidized zones of uranium-bearing hydrothermal deposits country — that is the host setting where oswaldpeetersite typically forms. If you start seeing studtite, meta-autunite, cuprosklodowskite in float, you are in the right ground. Field specimens usually show a acicular to lath-like crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find oswaldpeetersite on the map
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