Walpurgite is a rare secondary uranium-bismuth mineral typically found as thin, yellow, tabular crystals or radiating sprays in oxidized hydrothermal veins. It is highly prized by collectors for its brilliant yellow fluorescence under UV light, though it requires careful handling due to its uranium content.
Is this walpurgite?
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 walpurgite with a known reference. Walpurgite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Walpurgite leaves a yellowish streak.
- 3Read the lusterHold the specimen under a strong light. Walpurgite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange-yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, radiating clusters, drusy coatings.
Often confused with
Walpurgite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Walpurgite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs — Walpurgite leaves yellowish, Torbernite leaves pale green; luster reads adamantine on Walpurgite and vitreous on Torbernite.
How to tell apart: Walpurgite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs — Walpurgite leaves yellowish, Autunite leaves pale yellow; luster reads adamantine on Walpurgite and pearly on Autunite.
How to tell apart: Streak differs — Walpurgite leaves yellowish, Mixite leaves white; luster reads adamantine on Walpurgite and vitreous on Mixite.
Often found alongside walpurgite
Minerals reported to co-occur with walpurgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (BiO)₄(UO₂)(AsO₄)₂·2H₂O
- Mohs hardness
- 3.5
- Density
- 5.76 g/cm³
- Colors
- Streak
- Yellowish
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Radiating Clusters, Drusy Coatings
- Cleavage
- Perfect On {001}
- Fluorescence
- Bright Yellow Under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-bismuth Deposits
- Typical price
- $50-300 per thumbnail specimen
Where rockhounds find walpurgite
Classic worldwide localities
- Schneeberg, Saxony, Germany
- Jáchymov, Czech Republic
- Wittichen, Germany
Field-hunting tip
Look in oxidized zones of uranium-bismuth deposits country — that is the host setting where walpurgite typically forms. If you start seeing torbernite, zeunerite, uranospinite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating clusters, drusy coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find walpurgite on the map
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