Francevillite is a rare secondary uranium vanadate mineral that typically forms vibrant yellow platy or tabular crystals. It is found in the oxidized zones of uranium deposits and is highly sought after by radioactive mineral collectors.
Is this francevillite?
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 francevillite with a known reference. Francevillite 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. Francevillite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Francevillite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, tabular aggregates, crusts.
Often confused with
Francevillite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside francevillite
Minerals reported to co-occur with francevillite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ba,Pb)(UO₂)₂(VO₄)₂·5H₂O
- Mohs hardness
- 2.5
- Density
- 5.0-5.5 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy Crystals, Tabular Aggregates, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Uranium Deposits in Sandstones
- Typical price
- $20-150 per specimen depending on size and crystal quality
Where rockhounds find francevillite
Classic worldwide localities
- Franceville, Gabon
- Katanga, DR Congo
- Utah, USA
Field-hunting tip
Look in oxidized uranium deposits in sandstones country — that is the host setting where francevillite typically forms. If you start seeing curite, uraninite, vandenbrandeite in float, you are in the right ground. Field specimens usually show a platy crystals, tabular aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find francevillite on the map
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