Uranotungstite is a rare secondary uranium mineral that forms as thin, yellow, platy crystals in the oxidation zones of uranium deposits. It is highly prized by collectors of radioactive minerals due to its scarcity and distinct crystalline habit. Due to its radioactive nature, it requires specialized handling and secure storage protocols.
Is this uranotungstite?
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 uranotungstite with a known reference. Uranotungstite 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: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: yellow, brownish, yellow brown, orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: microscopic crystals.
Often confused with
Uranotungstite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Uranotungstite leaves yellow, Autunite leaves pale yellow; luster reads dull on Uranotungstite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Uranotungstite leaves yellow, Torbernite leaves pale green; luster reads dull on Uranotungstite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
Often found alongside uranotungstite
Minerals reported to co-occur with uranotungstite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba(UO₂)₂W₂O₈(OH)₂·H₂O
- Mohs hardness
- ~2
- Density
- 4.27 g/cm³
- Streak
- Yellow
- Luster
- Dull
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Microscopic crystals
- Cleavage
- {010}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral formed in polymetallic base metal deposits
Where rockhounds find uranotungstite
Classic worldwide localities
- Menzenschwand and the Clara mine, near Oberwolfach, Black Forest, Germany
Field-hunting tip
Where it forms: A rare secondary mineral formed in polymetallic base metal deposits. If you start seeing metauranocircite, metaheinrichite, bergenite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify uranotungstite?+
Where is uranotungstite found?+
Is uranotungstite safe to handle?+
What rocks look like uranotungstite?+
What minerals are found with uranotungstite?+
What kind of rock does uranotungstite form in?+
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Find uranotungstite on the map
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