Uroxite is a rare uranium hydroxide, typically light yellow. It occurs in post-mining, secondary efflorescent crusts on asphaltum-quartz matrix of mine walls. It is associated with feynmanite and gypsum. It was first described from the Burro mine, Slick Rock district, San Miguel Co., Colorado, USA.
Is this uroxite?
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 uroxite with a known reference. Uroxite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Uroxite leaves a very pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Uroxite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, radiated aggregates.
Often confused with
Uroxite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Uroxite leaves very pale yellow, Uranophane leaves yellowish white.
How to tell apart: Kasolite is the harder of the two (Mohs 4-5 vs. 2-3); streak differs, so Uroxite leaves very pale yellow, Kasolite leaves yellow; luster reads vitreous on Uroxite and greasy on Kasolite.
Often found alongside uroxite
Minerals reported to co-occur with uroxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- [(UO₂)₂(C₂O₄)(OH)₂(H₂O)₂]·H₂O
- Mohs hardness
- 2-3
- Density
- 4.187 g/cm³
- Colors
- Streak
- Very Pale Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Radiated Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-molybdenum Deposits
Where rockhounds find uroxite
Classic worldwide localities
- Jachymov, Czech Republic
- Katanga, DR Congo
- Utah, USA
Field-hunting tip
Look in oxidized zones of uranium-molybdenum deposits country, the host setting where uroxite typically forms. If you start seeing uraninite, gummite, molybdenite in float, you are in the right ground. Field specimens usually show a fibrous, radiated aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find uroxite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
