Uranosphaerite is a rare secondary uranium mineral that typically forms distinct orange, spherical, or globular radiating crystal aggregates. It is most commonly found in historical bismuth-uranium mining districts in Europe, often associated with altered uraninite. Due to its radioactive nature and scarcity, it is sought after primarily by advanced mineral collectors specializing in uranium or bismuth species.
Is this uranosphaerite?
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 uranosphaerite with a known reference. Uranosphaerite 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. Uranosphaerite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Uranosphaerite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: orange, orange-yellow, yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: globular, spherical aggregates, crusts.
Often confused with
Uranosphaerite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside uranosphaerite
Minerals reported to co-occur with uranosphaerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi(UO₂)O₂OH
- Mohs hardness
- 2-3
- Density
- 6.32 g/cm³
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Globular, Spherical Aggregates, Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Uranium-bearing Veins
- Typical price
- $50-300 thumbnail, $200-800 cabinet
Where rockhounds find uranosphaerite
Classic worldwide localities
- Schneeberg, Saxony, Germany
- Jáchymov, Czech Republic
Field-hunting tip
Look in hydrothermal uranium-bearing veins country — that is the host setting where uranosphaerite typically forms. If you start seeing uraninite, bismuth, quartz in float, you are in the right ground. Field specimens usually show a globular, spherical aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify uranosphaerite?+
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Find uranosphaerite on the map
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