Leydetite is a rare hydrated iron uranyl sulfate mineral typically found as a secondary mineral in uranium-bearing deposits. It forms distinct, small yellow prismatic crystals that are highly sought after by collectors of rare radioactive species.
Is this leydetite?
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 leydetite with a known reference. Leydetite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pale yellow, greenish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Leydetite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside leydetite
Minerals reported to co-occur with leydetite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe(UO₂)(SO₄)₂·11H₂O
- Mohs hardness
- ~2
- Density
- 2.55 g/cm³
- Colors
- Streak
- Yellowish white
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxidized zone of a uranium deposit
Where rockhounds find leydetite
Classic worldwide localities
- Mas d’Alary uranium deposit, Lodève, Hérault, France
Field-hunting tip
Where it forms: A secondary mineral in the oxidized zone of a uranium deposit. If you start seeing pyrite, uraninite, calcite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify leydetite?+
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What rocks look like leydetite?+
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Find leydetite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
