Kapundaite is an extremely rare phosphate mineral that typically forms as small, bright yellow to orange-yellow radiating blades. It is primarily found as a secondary mineral in the oxidized zones of copper deposits, often occurring on limonite-rich matrices.
Is this kapundaite?
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 kapundaite with a known reference. Kapundaite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kapundaite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Kapundaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-orange.
- 5Look at form & habitCrystal system: triclinic. Typical habit: bladed to lath-like crystals, often in radial sprays or crusts.
Often confused with
Kapundaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kapundaite
Minerals reported to co-occur with kapundaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Ca)₂(Fe³⁺,Mg)₄(PO₄)₄(OH)₂·5H₂O
- Mohs hardness
- 3
- Density
- 3.31 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Bladed to Lath-like Crystals, Often in Radial Sprays or Crusts
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Copper Ore Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find kapundaite
Classic worldwide localities
- Kapunda Copper Mine, South Australia
- Brumado, Bahia, Brazil
Field-hunting tip
Look in oxidized zones of copper ore deposits country, the host setting where kapundaite typically forms. If you start seeing chalcosiderite, goethite, libethenite in float, you are in the right ground. Field specimens usually show a bladed to lath-like crystals, often in radial sprays or crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find kapundaite on the map
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