Wölsendorfite is a rare secondary uranium mineral typically forming as an alteration product of uraninite. Collectors should look for its distinctive orange to red platy crystals often associated with fluorite or other secondary uranium minerals in oxidized vein deposits.
Is this wölsendorfite?
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 wölsendorfite with a known reference. Wölsendorfite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: red, carmine red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: aggregates, platy.
Often confused with
Wölsendorfite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Wölsendorfite is noticeably harder (Mohs 5 vs. 3-4); streak differs, so Wölsendorfite leaves yellowish-orange, Fourmarierite leaves orange; luster reads vitreous to adamantine on Wölsendorfite and adamantine to subadamantine on Fourmarierite.
How to tell apart: Streak differs, so Wölsendorfite leaves yellowish-orange, Curite leaves orange; luster reads vitreous to adamantine on Wölsendorfite and adamantine on Curite.
How to tell apart: Wölsendorfite is noticeably harder (Mohs 5 vs. 4); streak differs, so Wölsendorfite leaves yellowish-orange, Vandenbrandeite leaves green.
Often found alongside wölsendorfite
Minerals reported to co-occur with wölsendorfite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₇(UO₂)₁₄O₁₉(OH)₄·12H₂O
- Mohs hardness
- 5
- Density
- 6.8 g/cm³
- Colors
- Streak
- Yellowish-orange
- Luster
- Vitreous to adamantine
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Aggregates, platy
- Cleavage
- {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare alteration product of uraninite in the oxide zone of uranium-bearing mineral deposits
Where rockhounds find wölsendorfite
Classic worldwide localities
- Williams quarry, near Easton, Northampton Co., Pennsylvania, USA
- Branchville, Fairfield Co., Connecticut, USA
- Hell Hole claims, Wheeler Basin, Grand Co., Colorado, USA
- Wölsendorf, Bavaria, Germany
- Kerségalec, near Lignol, Morbihan, France
- Val Rendena, Trentino-Alto Adige, Italy
Field-hunting tip
Where it forms: A rare alteration product of uraninite in the oxide zone of uranium-bearing mineral deposits. If you start seeing uraninite, rutherfordine, becquerelite in float, you are in the right ground. Typical habit: aggregates, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wölsendorfite?+
Where is wölsendorfite found?+
Is wölsendorfite safe to handle?+
What rocks look like wölsendorfite?+
What minerals are found with wölsendorfite?+
What kind of rock does wölsendorfite form in?+
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Find wölsendorfite on the map
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