Ranunculite is a rare secondary uranium mineral typically found as bright yellow botryoidal crusts. It is named for its buttercup-yellow color and is primarily collected by specialized radioactive mineral enthusiasts.
Is this ranunculite?
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 ranunculite with a known reference. Ranunculite 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. Ranunculite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ranunculite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: yellow, bright yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, crusts, earthy aggregates.
Often confused with
Ranunculite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ranunculite leaves yellow, Autunite leaves pale yellow; luster reads dull on Ranunculite and pearly on Autunite.
How to tell apart: Streak differs — Ranunculite leaves yellow, Torbernite leaves pale green; luster reads dull on Ranunculite and vitreous on Torbernite.
Often found alongside ranunculite
Minerals reported to co-occur with ranunculite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlH(UO₂)₂(PO₄)₂(OH)₂·9H₂O
- Mohs hardness
- 2-3
- Density
- 3.2 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, Crusts, Earthy Aggregates
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Phosphate-rich Shales
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find ranunculite
Classic worldwide localities
- Revin, Ardennes, France
Field-hunting tip
Look in metamorphosed phosphate-rich shales country — that is the host setting where ranunculite typically forms. If you start seeing variscite, meta-autunite, uraninite in float, you are in the right ground. Field specimens usually show a botryoidal, crusts, earthy aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ranunculite on the map
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