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 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chadwickite leaves a pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Chadwickite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, crusts.
Often confused with
Chadwickite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Chadwickite leaves pale yellow, Meta-autunite leaves yellow; luster reads vitreous on Chadwickite and pearly on Meta-autunite.
How to tell apart: Streak differs — Chadwickite leaves pale yellow, Torbernite leaves pale green.
How to tell apart: Streak differs — Chadwickite leaves pale yellow, Zeunerite leaves pale green; luster reads vitreous on Chadwickite and pearly 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
- (UO₂)(HAsO₄)·4H₂O
- Mohs hardness
- 2-3
- Density
- 4.6-4.8 g/cm³
- Colors
- Streak
- Pale Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular Crystals, Crusts
- Cleavage
- Perfect Basal
- Fluorescence
- Bright Green Under UV Light
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Uranium Veins
- Typical price
- $50-300 per specimen
Where rockhounds find chadwickite
Classic worldwide localities
- Jáchymov, Czech Republic
- Great Bear Lake, Canada
- White Canyon, Utah, USA
Field-hunting tip
Look in hydrothermal uranium veins country — that is the host setting where chadwickite typically forms. If you start seeing uraninite, arsenopyrite, goethite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find chadwickite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
