Mounanaite is a rare lead-iron vanadate mineral that typically forms as small, tabular red-brown crystals or crusts. It is best known from its type locality in the Mounana mine of Gabon, often occurring in oxidized ore zones associated with other secondary lead minerals.
Is this mounanaite?
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 mounanaite with a known reference. Mounanaite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: brownish red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular, twinning common.
Often confused with
Mounanaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Mounanaite is noticeably harder (Mohs 4.5 vs. 3-3.5); streak differs, so Mounanaite leaves yellowish brown, Descloizite leaves orange to brownish red; luster reads adamantine on Mounanaite and greasy on Descloizite.
How to tell apart: Mounanaite is noticeably harder (Mohs 4.5 vs. 2.5-3); streak differs, so Mounanaite leaves yellowish brown, Vanadinite leaves white to pale red or pale yellow; luster reads adamantine on Mounanaite and subresinous to subadamantine on Vanadinite.
Often found alongside mounanaite
Minerals reported to co-occur with mounanaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbFe²⁺Fe³⁺(VO₄)₂(OH)₂
- Mohs hardness
- 4.5
- Density
- 4.85 g/cm³
- Colors
- Streak
- Yellowish brown
- Luster
- Adamantine
- Transparency
- Translucent to transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular, twinning common
- Cleavage
- On {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral in the oxidized zone of a sediment-hosted U–V deposit
Where rockhounds find mounanaite
Classic worldwide localities
- Mounana uranium mine, Franceville, Gabon
Field-hunting tip
Where it forms: A rare mineral in the oxidized zone of a sediment-hosted U–V deposit. If you start seeing francevillite, curienite, vanuralite in float, you are in the right ground. Typical habit: tabular, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
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Find mounanaite on the map
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