Uranophane is a secondary uranium silicate that typically forms striking, vibrant yellow radiating tufts or fibrous coatings on host rock. It is a highly fluorescent mineral that glows bright neon green under ultraviolet light, making it a favorite for collectors of radioactive suites. It is commonly found as an alteration product in the oxidation zones of uranium-rich ore bodies.
Is this uranophane?
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 uranophane with a known reference. Uranophane sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Uranophane leaves a pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Uranophane typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, lemon-yellow, orange-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, fibrous, radiating clusters, drusy coatings.
Often confused with
Uranophane vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Uranophane and pearly on Autunite.
How to tell apart: Kasolite is the harder of the two (Mohs 4-5 vs. 2.5); streak differs — Uranophane leaves pale yellow, Kasolite leaves yellow; luster reads vitreous on Uranophane and greasy on Kasolite.
How to tell apart: Boltwoodite is the harder of the two (Mohs 3.5 vs. 2.5); streak differs — Uranophane leaves pale yellow, Boltwoodite leaves yellow; luster reads vitreous on Uranophane and pearly on Boltwoodite.
Often found alongside uranophane
Minerals reported to co-occur with uranophane. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(UO₂)₂(SiO₃OH)₂·5H₂O
- Mohs hardness
- 2.5
- Density
- 3.8-3.9 g/cm³
- Streak
- Pale Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, Fibrous, Radiating Clusters, Drusy Coatings
- Cleavage
- Perfect in One Direction
- Fluorescence
- Bright Green Under SW and LW UV
- Rarity
- Common
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-bearing Hydrothermal Deposits
- Typical price
- $10-150 depending on specimen size and aesthetic quality
Where rockhounds find uranophane
1 mapped spotsClassic worldwide localities
- Democratic Republic of the Congo
- Germany
- USA (Utah, Wyoming)
- France
- Canada
Field-hunting tip
Look in oxidized zones of uranium-bearing hydrothermal deposits country — that is the host setting where uranophane typically forms. If you start seeing autunite, gummite, torbernite in float, you are in the right ground. Field specimens usually show a acicular, fibrous, radiating clusters, drusy coatings habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming — start trip planning there.
Common questions
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Find uranophane on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
