Ianbruceite is a rare zinc arsenate that forms sky blue to pale blue aggregates of thin flakes and tapered platy crystals. It is a secondary mineral in the oxidized zone of a polymetallic sulfide deposit. Associated minerals include leiteite, legrandite and adamite. It was first described from the "Zinc pocket" on the 44 level, Tsumeb mine, Otjikoto (Oshikoto) region, Namibia.
Is this ianbruceite?
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 ianbruceite with a known reference. Ianbruceite sits at Mohs 1, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: sky blue, pale blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates of thin flakes and tapered platy crystals.
Often confused with
Ianbruceite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ianbruceite
Minerals reported to co-occur with ianbruceite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₂(AsO₄)(OH)(H₂O)·2H₂O
- Mohs hardness
- 1
- Density
- 3.197 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates of thin flakes and tapered platy crystals
- Cleavage
- Perfect on (100)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxidized zone of a polymetallic sulfide deposit
Where rockhounds find ianbruceite
Classic worldwide localities
- Tsumeb Mine, Namibia
Field-hunting tip
Where it forms: A secondary mineral in the oxidized zone of a polymetallic sulfide deposit. If you start seeing leiteite, köttigite, legrandite in float, you are in the right ground. Typical habit: aggregates of thin flakes and tapered platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ianbruceite?+
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What rocks look like ianbruceite?+
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Find ianbruceite on the map
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