Cuprosklodowskite is a striking secondary uranium mineral that forms beautiful, bright green acicular or fibrous needle-like crystals. It is highly sought after by collectors for its vivid color and intense green fluorescence under UV light, though it requires specialized storage due to its radioactivity and fragility.
Is this cuprosklodowskite?
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 cuprosklodowskite with a known reference. Cuprosklodowskite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to silky in aggregates.
- 4Match the color rangeCompare against the expected color range: grass green, green yellow, light green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular, radial.
Often confused with
Cuprosklodowskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cuprosklodowskite leaves greenish yellow, Vandenbrandeite leaves green; luster reads dull to silky in aggregates on Cuprosklodowskite and vitreous on Vandenbrandeite.
How to tell apart: Cuprosklodowskite is noticeably harder (Mohs 4 vs. 2-2.5); streak differs, so Cuprosklodowskite leaves greenish yellow, Torbernite leaves pale green; luster reads dull to silky in aggregates on Cuprosklodowskite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
How to tell apart: Cuprosklodowskite is noticeably harder (Mohs 4 vs. 2-2.5); streak differs, so Cuprosklodowskite leaves greenish yellow, Autunite leaves pale yellow; luster reads dull to silky in aggregates on Cuprosklodowskite and vitreous, pearly on {001} on Autunite.
Often found alongside cuprosklodowskite
Minerals reported to co-occur with cuprosklodowskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu(UO₂)₂(SiO₃OH)₂·6H₂O
- Mohs hardness
- 4
- Density
- 3.85 g/cm³
- Streak
- Greenish yellow
- Luster
- Dull to silky in aggregates
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Acicular, radial
- Cleavage
- {100}
- Fluorescence
- Bright green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by alteration of earlier uranium minerals, both in situ and after transport of solutions
Where rockhounds find cuprosklodowskite
Classic worldwide localities
- Sanostee area, San Juan Co., in the Woodrow mine, Laguna district, Valencia Co., and in the Grants district, McKinley Co., New Mexico, USA
- Frey No. 4 mine, Frey Canyon, the Posey mine, Red Canyon, and the Happy Jack mine, White Canyon, San Juan Co., Utah, USA
- Ram claims, Pinto Mountains, Riverside Co., California, USA
- Congo (Zaire), from Katanga (Shaba) Province, at Kambove and Kalongwe, Shinkolobwe and the Musonoi mine, Kolwezi
- Jáchymov (Joachimsthal), Czech Republic
- Johanngeorgenstadt, Saxony, Germany
Field-hunting tip
Where it forms: A secondary mineral formed by alteration of earlier uranium minerals, both in situ and after transport of solutions. If you start seeing becquerelite, brochantite, uranophane in float, you are in the right ground. Typical habit: acicular, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cuprosklodowskite?+
Where is cuprosklodowskite found?+
Is cuprosklodowskite safe to handle?+
What rocks look like cuprosklodowskite?+
What minerals are found with cuprosklodowskite?+
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Find cuprosklodowskite on the map
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