Carrboydite is a rare secondary mineral typically found as botryoidal coatings or crusts in the oxidized zones of nickel sulfide deposits. It is often identified by its distinct pale green color and its association with weathered nickel-bearing minerals. Collectors prize it for its unique, though delicate, crystalline morphology found in specific arid Australian mining regions.
Is this carrboydite?
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 carrboydite with a known reference. Carrboydite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to waxy.
- 4Match the color rangeCompare against the expected color range: blue green, yellow green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: nodular, platy.
Often confused with
Carrboydite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Carrboydite leaves greenish white, Woodwardite leaves light blue; luster reads dull to waxy on Carrboydite and pearly on Woodwardite.
How to tell apart: Streak differs, so Carrboydite leaves greenish white, Goslarite leaves white; luster reads dull to waxy on Carrboydite and vitreous, silky if fibrous on Goslarite.
How to tell apart: Streak differs, so Carrboydite leaves greenish white, Morenosite leaves pale green to white; luster reads dull to waxy on Carrboydite and vitreous on Morenosite.
Often found alongside carrboydite
Minerals reported to co-occur with carrboydite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ni₁₄Al₉(SO₄)₆(OH)₄₃·7H₂O
- Mohs hardness
- 2
- Density
- 2.50 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Dull to waxy
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Nodular, platy
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of nickel sulfide deposits
Where rockhounds find carrboydite
Classic worldwide localities
- Carr Boyd Rocks nickel mine, Yerilla district, 80 km north-northeast of Kalgoorlie, and at the 132 North nickel mine, 4 km southwest of Widgiemooltha, Western Australia
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of nickel sulfide deposits. If you start seeing malachite, azurite, paratacamite in float, you are in the right ground. Typical habit: nodular, platy. Train your eye for that shape before scanning the outcrop.
Common questions
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Find carrboydite on the map
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