Uranocircite is a brilliant yellow secondary uranium mineral often found as thin, square, tabular crystals or micaceous flakes. It is highly sought after by collectors for its striking neon-green fluorescence under ultraviolet light. Due to its radioactive nature, it should always be handled with care and stored in a secure, isolated container.
Is this uranocircite?
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 uranocircite with a known reference. Uranocircite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: yellow, yellow green.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: foliated, tabular.
Often confused with
Uranocircite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Uranocircite leaves light yellow, Autunite leaves pale yellow; luster reads pearly on Uranocircite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Uranocircite leaves light yellow, Torbernite leaves pale green; luster reads pearly on Uranocircite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
Often found alongside uranocircite
Minerals reported to co-occur with uranocircite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba(UO₂)₂(PO₄)₂·10-12H₂O
- Mohs hardness
- 2-2.5
- Density
- 3.46 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Pearly
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Foliated, tabular
- Cleavage
- Perfect on {001}; distinct on {100}
- Fluorescence
- Green under SW and LW UV
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Secondary mineral in quartz veins with other secondary uranium minerals
Where rockhounds find uranocircite
Classic worldwide localities
- Bergen, near Falkenstein in Voigtland, Saxony, Germany (type locality)
Field-hunting tip
Where it forms: Secondary mineral in quartz veins with other secondary uranium minerals. If you start seeing autunite, torbernite, uraninite in float, you are in the right ground. Typical habit: foliated, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify uranocircite?+
Where is uranocircite found?+
Is uranocircite safe to handle?+
What rocks look like uranocircite?+
What minerals are found with uranocircite?+
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Find uranocircite on the map
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