Rameauite is a rare secondary uranium mineral that forms distinct, often radial, yellow-orange prismatic crystals. It is primarily found in the oxidized zones of uranium-rich hydrothermal deposits and is highly sought after by collectors of radioactive minerals due to its scarcity and aesthetic crystal form.
Is this rameauite?
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 rameauite with a known reference. Rameauite 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. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, pseudo hexagonal.
Often confused with
Rameauite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Rameauite and adamantine to greasy on Becquerelite.
How to tell apart: Luster reads vitreous on Rameauite and adamantine on Billietite.
How to tell apart: Streak differs, so Rameauite leaves yellow, Fourmarierite leaves orange; luster reads vitreous on Rameauite and adamantine to subadamantine on Fourmarierite.
Often found alongside rameauite
Minerals reported to co-occur with rameauite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Ca(UO₂)₆O₆(OH)₄(H₂O)₅·H₂O
- Mohs hardness
- 2-3
- Density
- 5.60 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, pseudo hexagonal
- Cleavage
- Good on {010}
- Fluorescence
- Bright yellow under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidation zone of uranium deposits
Where rockhounds find rameauite
Classic worldwide localities
- Found in the Orphan mine, Grand Canyon, Coconino Co., Arizona, USA
- Margnac mine, Compreignac, Haute-Vienne, France
- Shinkolobwe, Katanga Province, Congo (Shaba Province, Zaire)
Field-hunting tip
Where it forms: In the oxidation zone of uranium deposits. If you start seeing calcite, uranophane, uraninite in float, you are in the right ground. Typical habit: prismatic, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
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Find rameauite on the map
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