Uramarsite is a rare secondary uranium mineral typically found in oxidized zones of uranium deposits. It usually appears as bright yellow to yellow-green platy crystals that resemble mica, often found as coatings or clusters on matrix rock.
Is this uramarsite?
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 uramarsite with a known reference. Uramarsite 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. Uramarsite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Uramarsite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals, micaceous aggregates.
Often confused with
Uramarsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Uramarsite leaves yellow, Autunite leaves pale yellow.
How to tell apart: Streak differs — Uramarsite leaves yellow, Torbernite leaves pale green; luster reads pearly on Uramarsite and vitreous on Torbernite.
Often found alongside uramarsite
Minerals reported to co-occur with uramarsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (H₃O,Ca,Pb)₂(UO₂)₂(AsO₄,PO₄)₂·nH₂O
- Mohs hardness
- 2-3
- Density
- 3.3-3.6 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Platy Crystals, Micaceous Aggregates
- Cleavage
- Perfect Basal
- Fluorescence
- Strong Yellow-green Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins, Uranium Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find uramarsite
Classic worldwide localities
- Jáchymov, Czech Republic
- Schneeberg, Germany
- Les Montmins, France
Field-hunting tip
Look in hydrothermal veins, uranium deposits country — that is the host setting where uramarsite typically forms. If you start seeing uraninite, meta-torbernite, pharmacosiderite in float, you are in the right ground. Field specimens usually show a platy crystals, micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find uramarsite on the map
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