Urancalcarite is a rare secondary uranium mineral that typically forms as delicate, radiating tufts of acicular crystals. It is primarily found in the oxidized zones of uranium deposits and is highly prized by collectors for its brilliant neon-yellow fluorescence under UV light.
Is this urancalcarite?
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 urancalcarite with a known reference. Urancalcarite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Urancalcarite leaves a light yellow streak.
- 3Read the lusterHold the specimen under a strong light. Urancalcarite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular or fibrous radial aggregates.
Often confused with
Urancalcarite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Urancalcarite leaves light yellow, Uranophane leaves pale yellow; luster reads pearly on Urancalcarite and vitreous on Uranophane.
How to tell apart: Streak differs — Urancalcarite leaves light yellow, Liebigite leaves pale yellow; luster reads pearly on Urancalcarite and vitreous on Liebigite.
Often found alongside urancalcarite
Minerals reported to co-occur with urancalcarite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(UO₂)₄(CO₃)(OH)₆·3H₂O
- Mohs hardness
- 2.5
- Density
- 4.15 g/cm³
- Colors
- Streak
- Light Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Fibrous Radial Aggregates
- Cleavage
- Perfect
- Fluorescence
- Bright Yellow-green Under UV Light
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find urancalcarite
Classic worldwide localities
- Tyuya-Muyun District, Kyrgyzstan
- Jáchymov, Czech Republic
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where urancalcarite typically forms. If you start seeing uraninite, calcite, rutherfordine in float, you are in the right ground. Field specimens usually show a acicular or fibrous radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify urancalcarite?+
Where is urancalcarite found?+
How much is urancalcarite worth?+
Is urancalcarite safe to handle?+
What rocks look like urancalcarite?+
What minerals are found with urancalcarite?+
What kind of rock does urancalcarite form in?+
What is urancalcarite used for?+
Find urancalcarite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
