Metacalciouranoite is an extremely rare secondary uranium mineral typically found as an alteration product in oxidized uranium-rich deposits. It is best identified by its distinct yellowish color, greasy luster, and characteristic radioactive nature, often appearing as platy crusts or earthy masses.
Is this metacalciouranoite?
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 metacalciouranoite with a known reference. Metacalciouranoite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Metacalciouranoite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Metacalciouranoite typically shows a greasy luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, granular aggregates.
Often confused with
Metacalciouranoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Metacalciouranoite leaves yellow, Uranophane leaves pale yellow; luster reads greasy on Metacalciouranoite and vitreous on Uranophane.
How to tell apart: Streak differs, so Metacalciouranoite leaves yellow, Autunite leaves pale yellow; luster reads greasy on Metacalciouranoite and pearly on Autunite.
How to tell apart: Luster reads greasy on Metacalciouranoite and adamantine on Becquerelite.
Often found alongside metacalciouranoite
Minerals reported to co-occur with metacalciouranoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Ba)U₂O₇·2H₂O
- Mohs hardness
- 3-4
- Density
- 4.8-5.2 g/cm³
- Streak
- Yellow
- Luster
- Greasy
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy Crystals, Granular Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find metacalciouranoite
Classic worldwide localities
- Khovalyg-Aksy, Tuva, Russia
- Tyuya-Muyun, Kyrgyzstan
Field-hunting tip
Look in oxidized zones of uranium deposits country, the host setting where metacalciouranoite typically forms. If you start seeing uraninite, calcite, gummite in float, you are in the right ground. Field specimens usually show a platy crystals, granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify metacalciouranoite?+
Where is metacalciouranoite found?+
How much is metacalciouranoite worth?+
Is metacalciouranoite safe to handle?+
What rocks look like metacalciouranoite?+
What minerals are found with metacalciouranoite?+
What kind of rock does metacalciouranoite form in?+
What is metacalciouranoite used for?+
Find metacalciouranoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
