Chadwickite is a rare secondary uranium arsenate mineral that typically forms as small, yellow, tabular crystals or coatings on uranium-bearing ores. It is primarily sought after by specialist collectors of radioactive minerals due to its rarity and distinct fluorescence under ultraviolet light.
Is this chadwickite?
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 chadwickite with a known reference. Chadwickite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: encrustations.
Often confused with
Chadwickite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull on Chadwickite and pearly to dull on Meta-autunite.
How to tell apart: Streak differs, so Chadwickite leaves yellow, Torbernite leaves pale green; luster reads dull on Chadwickite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
How to tell apart: Streak differs, so Chadwickite leaves yellow, Zeunerite leaves pale green; luster reads dull on Chadwickite and vitreous on Zeunerite.
Often found alongside chadwickite
Minerals reported to co-occur with chadwickite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- UO₂HAsO₃
- Mohs hardness
- 2
- Density
- 4.86 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Dull
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Encrustations
- Cleavage
- Perfect on {001}
- Fluorescence
- Bright green under UV light
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in a uranium deposit
Where rockhounds find chadwickite
Classic worldwide localities
- Wittichen in the Black Forest, Aufschluss, Germany (type locality)
Field-hunting tip
Where it forms: A secondary mineral in a uranium deposit. If you start seeing uraninite, metakahlerite, abernathyite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like chadwickite?+
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Find chadwickite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
