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. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: silky.
- 4Match the color rangeCompare against the expected color range: pale, golden yellow.
- 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.
How to tell apart: Streak differs, so Kapundaite leaves yellow, Arthurite leaves light green; luster reads silky on Kapundaite and vitreous on Arthurite.
How to tell apart: Streak differs, so Kapundaite leaves yellow, Dufrénite leaves green; luster reads silky on Kapundaite and vitreous to silky on Dufrénite.
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
- CaNaFe₄(PO₄)₄(OH)₃·5H₂O
- Mohs hardness
- ~3
- Density
- 2.93 g/cm³
- Colors
- PaleGolden yellow
- Streak
- Yellow
- Luster
- Silky
- Transparency
- Translucent to transparent
- Crystal system
- Triclinic
- Crystal habit
- Bladed to lath-like crystals, often in radial sprays or crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a phosphorite deposit that has undergone metamorphism, followed by weathering and secondary enrichment
Where rockhounds find kapundaite
Classic worldwide localities
- Toms phosphate quarry, 8 km east-southeast of Kapunda, South Australia, Australia
Field-hunting tip
Where it forms: In a phosphorite deposit that has undergone metamorphism, followed by weathering and secondary enrichment. If you start seeing leucophosphite, natrodufrenite, meurigite-na in float, you are in the right ground. Typical habit: bladed to lath-like crystals, often in radial sprays or crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kapundaite?+
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Find kapundaite on the map
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