Phosphowalpurgite is a rare secondary uranium phosphate mineral that forms as a constituent in the oxidation zones of uranium-bismuth deposits. It is best identified by its bright yellow, tabular crystal plates and association with other secondary uranium minerals. Due to its radioactive nature, it is strictly for advanced mineral collectors who understand proper safety and storage protocols.
Is this phosphowalpurgite?
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 phosphowalpurgite with a known reference. Phosphowalpurgite 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: light brownish grey.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: brownish gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: encrustations, euhedral crystals.
Often confused with
Phosphowalpurgite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Phosphowalpurgite is noticeably harder (Mohs <5 vs. 3.5); streak differs, so Phosphowalpurgite leaves light brownish grey, Walpurgite leaves pale brownish yellow; luster reads vitreous to adamantine on Phosphowalpurgite and adamantine to greasy on Walpurgite.
How to tell apart: Phosphowalpurgite is noticeably harder (Mohs <5 vs. 2-2.5); streak differs, so Phosphowalpurgite leaves light brownish grey, Torbernite leaves pale green.
Often found alongside phosphowalpurgite
Minerals reported to co-occur with phosphowalpurgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (UO₂)Bi₄O₄(PO₄)₂(H₂O)₂
- Mohs hardness
- <5
- Density
- 6.36 g/cm³
- Colors
- Streak
- Light brownish grey
- Luster
- Vitreous to adamantine
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Encrustations, euhedral crystals
- Cleavage
- {010}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by weathering of primary bismuth and uraninite in hydrothermal quartz veins
Where rockhounds find phosphowalpurgite
Classic worldwide localities
- Ore depost near Smrkovec,k in western Bohemia, Czech Republic (type locality)
Field-hunting tip
Where it forms: A secondary mineral formed by weathering of primary bismuth and uraninite in hydrothermal quartz veins. If you start seeing apatite, atelestite, bismutoferrite in float, you are in the right ground. Typical habit: encrustations, euhedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify phosphowalpurgite?+
Where is phosphowalpurgite found?+
Is phosphowalpurgite safe to handle?+
What rocks look like phosphowalpurgite?+
What minerals are found with phosphowalpurgite?+
What kind of rock does phosphowalpurgite form in?+
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Find phosphowalpurgite on the map
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