Leguernite is an extremely rare secondary uranium mineral typically found as small, yellow, tabular crystals. Collectors should look for it in the oxidation zones of uranium deposits, often occurring in association with other rare secondary uranium species.
Is this leguernite?
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 leguernite with a known reference. Leguernite 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. Leguernite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Leguernite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, pale yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Leguernite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Leguernite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Leguernite and pearly on Autunite.
How to tell apart: Streak differs — Leguernite leaves yellow, Uranophane leaves pale yellow.
Often found alongside leguernite
Minerals reported to co-occur with leguernite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₆(UO₂)₄(SO₄)₂(OH)₁₆·4H₂O
- Mohs hardness
- 2.5
- Density
- 3.55 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Fluorescence
- Bright Green Under UV Light
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Uranium-bearing Hydrothermal Veins
- Typical price
- $50-300 per specimen depending on size and crystal quality
Where rockhounds find leguernite
Classic worldwide localities
- La Crouzille, France
Field-hunting tip
Look in uranium-bearing hydrothermal veins country — that is the host setting where leguernite typically forms. If you start seeing uraninite, pyromorphite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find leguernite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
