Protasite is a rare barium-uranium mineral known primarily from the Shinkolobwe mine in the Congo. It typically forms thin, orange, tabular crystals and is a highly sought-after species for advanced radioactive mineral collectors.
Is this protasite?
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 protasite with a known reference. Protasite 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: yellow-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: light orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy, pseudo hexagonal.
Often confused with
Protasite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Protasite leaves yellow-orange, Becquerelite leaves yellow; luster reads subadamantine on Protasite and adamantine to greasy on Becquerelite.
How to tell apart: Streak differs, so Protasite leaves yellow-orange, Fourmarierite leaves orange; luster reads subadamantine on Protasite and adamantine to subadamantine on Fourmarierite.
Often found alongside protasite
Minerals reported to co-occur with protasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba(UO₂)₃O₃(OH)₂(H₂O)₃
- Mohs hardness
- 2.5
- Density
- 5.39 g/cm³
- Colors
- Streak
- Yellow-orange
- Luster
- Subadamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy, pseudo hexagonal
- Cleavage
- Good on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidized zone of uranium-bearing mineral deposits
Where rockhounds find protasite
Classic worldwide localities
- Shinkolobwe, Katanga Province, Congo (Shaba Province, Zaire)
Field-hunting tip
Where it forms: In the oxidized zone of uranium-bearing mineral deposits. If you start seeing uraninite, uranophane, bauranoite in float, you are in the right ground. Typical habit: platy, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify protasite?+
Where is protasite found?+
Is protasite safe to handle?+
What rocks look like protasite?+
What minerals are found with protasite?+
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Find protasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
