Cousinite is a rare, radioactive uranium mineral found primarily as a secondary oxidation product in uranium-rich deposits. It typically presents as earthy yellow crusts or coatings and is highly sought after by radioactive mineral specialists due to its scarcity and distinct association with the Shinkolobwe mine.
Is this cousinite?
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 cousinite with a known reference. Cousinite 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. Cousinite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Cousinite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown.
- 5Look at form & habitCrystal system: amorphous. Typical habit: crusts, powdery coatings, massive.
Often confused with
Cousinite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Cousinite leaves yellow, Uranophane leaves pale yellow; luster reads earthy on Cousinite and vitreous on Uranophane.
How to tell apart: Streak differs — Cousinite leaves yellow, Autunite leaves pale yellow; luster reads earthy on Cousinite and pearly on Autunite.
Often found alongside cousinite
Minerals reported to co-occur with cousinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg(UO₂)₂(MoO₄)₂(OH)₂·~5H₂O
- Mohs hardness
- 2-3
- Density
- 3.3-3.6 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Amorphous
- Crystal habit
- Crusts, Powdery Coatings, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find cousinite
Classic worldwide localities
- Shinkolobwe, Democratic Republic of the Congo
Field-hunting tip
Look in oxidized zones of uranium deposits country — that is the host setting where cousinite typically forms. If you start seeing uraninite, becquerelite, soddyite in float, you are in the right ground. Field specimens usually show a crusts, powdery coatings, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find cousinite on the map
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