Paulscherrerite is a rare uranium oxide mineral that forms as an alteration product of uraninite. It typically presents as small, dull, brownish octahedral crystals often associated with other uranium secondary minerals in hydrothermal deposits.
Is this paulscherrerite?
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 paulscherrerite with a known reference. Paulscherrerite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Paulscherrerite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Paulscherrerite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: brown, yellow-brown, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals.
Often confused with
Paulscherrerite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Paulscherrerite leaves yellow, Uraninite leaves brownish-black to greenish-black; luster reads submetallic on Paulscherrerite and submetallic to dull on Uraninite.
How to tell apart: Streak differs — Paulscherrerite leaves yellow, Uranium Ore leaves brownish-black.
Often found alongside paulscherrerite
Minerals reported to co-occur with paulscherrerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- UO₂·xH₂O
- Mohs hardness
- 5-6
- Density
- 9.5-10.5 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Veins
- Typical price
- $100-500 per specimen
Where rockhounds find paulscherrerite
Classic worldwide localities
- Schneeberg, Saxony, Germany
- Witwatersrand, South Africa
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where paulscherrerite typically forms. If you start seeing uraninite, gummite, quartz in float, you are in the right ground. Field specimens usually show a octahedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify paulscherrerite?+
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Find paulscherrerite on the map
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