Joliotite is a rare secondary uranium carbonate mineral typically found as thin, earthy crusts or powdery coatings in oxidized uranium-bearing deposits. It is best identified by its bright yellow color and association with other secondary uranium species, though it is often difficult to distinguish from other similar uranyl minerals without X-ray diffraction. Collectors should take extreme care when handling due to its radioactive nature.
Is this joliotite?
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 joliotite with a known reference. Joliotite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: lemon yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: scaly, spherical.
Often confused with
Joliotite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Joliotite leaves yellow, Urancalcarite leaves light yellow.
How to tell apart: Streak differs, so Joliotite leaves yellow, Autunite leaves pale yellow.
How to tell apart: Streak differs, so Joliotite leaves yellow, Zellerite leaves white; luster reads vitreous on Joliotite and earthy on Zellerite.
Often found alongside joliotite
Minerals reported to co-occur with joliotite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- UO₂(CO₃)·nH₂O
- Mohs hardness
- 1-2
- Density
- 4.04 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Scaly, spherical
- Cleavage
- {100}, probable
- Fluorescence
- Fluorescent
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized portions of a uranium deposit
Where rockhounds find joliotite
Classic worldwide localities
- Menzenschwand, Black Forest, Germany
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized portions of a uranium deposit. If you start seeing billietite, rutherfordine, studtite in float, you are in the right ground. Typical habit: scaly, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify joliotite?+
Where is joliotite found?+
Is joliotite safe to handle?+
What rocks look like joliotite?+
What minerals are found with joliotite?+
What kind of rock does joliotite form in?+
What is joliotite used for?+
Find joliotite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
