Widenmannite is an extremely rare lead uranyl carbonate that typically forms as small, tabular yellow crystals. It is primarily found in uranium-bearing hydrothermal deposits where it serves as a highly sought-after specimen for advanced mineral collectors due to its complex chemical structure.
Is this widenmannite?
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 widenmannite with a known reference. Widenmannite 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. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly to silky.
- 4Match the color rangeCompare against the expected color range: light yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular.
Often confused with
Widenmannite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Widenmannite leaves pale yellow, Vanmeersscheite leaves light yellow; luster reads pearly to silky on Widenmannite and vitreous on Vanmeersscheite.
How to tell apart: Luster reads pearly to silky on Widenmannite and vitreous, pearly on {001} on Autunite.
Often found alongside widenmannite
Minerals reported to co-occur with widenmannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂UO₂(CO₃)₂(OH)₂
- Mohs hardness
- ~2
- Density
- 6.89 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Pearly to silky
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of a hydrothermal As–Pb-bearing deposit (Michael mine, Germany); an alteration product of sulfides by sea water (Loe Warren zawn, England)
Where rockhounds find widenmannite
Classic worldwide localities
- Michael mine, Weiler, near Lahr, Black Forest, Germany
- Jáchymov (Joachimsthal), Czech Republic
- Loe Warren zawn, 0.75 km west of Botallack, St. Just, Cornwall, England
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of a hydrothermal As–Pb-bearing deposit (Michael mine, Germany); an alteration product of sulfides by sea water (Loe Warren zawn, England). If you start seeing hügelite, hallimondite, cerussite in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify widenmannite?+
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What rocks look like widenmannite?+
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Find widenmannite on the map
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