Zaïrite is a rare bismuth-iron phosphate mineral belonging to the alunite supergroup. It is typically found as small, vibrant yellow to greenish-brown crusts or minute crystals within hydrothermal mineral assemblages.
Is this zaïrite?
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 zaïrite with a known reference. Zaïrite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy.
- 4Match the color rangeCompare against the expected color range: greenish, greenish white, yellow green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: microcrystalline aggregates, crusts, or small rhombohedral crystals.
Often confused with
Zaïrite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Zaïrite leaves white, Corkite leaves yellow; luster reads waxy on Zaïrite and vitreous to resinous on Corkite.
How to tell apart: Streak differs, so Zaïrite leaves white, Beudantite leaves grayish yellow to green; luster reads waxy on Zaïrite and vitreous, resinous, may be frosted on Beudantite.
Often found alongside zaïrite
Minerals reported to co-occur with zaïrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiFe₃(PO₄)₂(OH)₆
- Mohs hardness
- 4.5
- Density
- 4.37 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Microcrystalline aggregates, crusts, or small rhombohedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral in the weathering zone of quartz wolframite deposits
Where rockhounds find zaïrite
Classic worldwide localities
- Eta-Etu district, northern Kivu Province, Congo (Zaire)
Field-hunting tip
Where it forms: A rare mineral in the weathering zone of quartz wolframite deposits. If you start seeing bismuth, bismutite, quartz in float, you are in the right ground. Typical habit: microcrystalline aggregates, crusts, or small rhombohedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zaïrite?+
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Find zaïrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
