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. Streak: yellowish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, yellow brown, yellow green, yellow orange, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: earthy, massive, radial.
Often confused with
Uranophane vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Uranophane leaves yellowish white, Autunite leaves pale yellow.
How to tell apart: Kasolite is the harder of the two (Mohs 4-5 vs. 2.5); streak differs, so Uranophane leaves yellowish white, Kasolite leaves pale yellow-brown; luster reads vitreous on Uranophane and subadamantine to greasy, dull to earthy when massive on Kasolite.
How to tell apart: Boltwoodite is the harder of the two (Mohs 3.5-4 vs. 2.5); streak differs, so Uranophane leaves yellowish white, Boltwoodite leaves white; luster reads vitreous on Uranophane and pearly; radial aggregates vitreous to silky; dull to earthy in microcrystalline pseudomorphs 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
- 3.9 g/cm³
- Streak
- Yellowish white
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Earthy, massive, radial
- Cleavage
- Perfect on {100}
- Fluorescence
- Weak yellow-green under SW and LW UV
- Rarity
- Common
- Uses
- Collector
- Host rock
- Alteration product of gummite
Where rockhounds find uranophane
1 mapped spotsClassic worldwide localities
- Oberpfalz, Bavaria (type locality)
Field-hunting tip
Where it forms: Alteration product of gummite. If you start seeing autunite, gummite, torbernite in float, you are in the right ground. Typical habit: earthy, massive, radial. 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
How do you identify uranophane?+
Where is uranophane found?+
Can I find uranophane in the United States?+
Is uranophane safe to handle?+
What rocks look like uranophane?+
What minerals are found with uranophane?+
What kind of rock does uranophane form in?+
What is uranophane used for?+
Find uranophane on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
