Gillardite is a rare copper-nickel hydroxychloride mineral that typically forms as delicate, bright green platy or micaceous aggregates. It is primarily identified by its characteristic vibrant green color and association with nickel ore deposits in oxidized zones. Due to its scarcity and fragile crystal habit, it is highly sought after by systematic mineral collectors.
Is this gillardite?
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 gillardite with a known reference. Gillardite 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: green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: aggregates, triangular crystals.
Often confused with
Gillardite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Gillardite leaves green, Atacamite leaves apple-green; luster reads vitreous on Gillardite and adamantine to vitreous on Atacamite.
How to tell apart: Streak differs, so Gillardite leaves green, Clinoatacamite leaves greenish white; luster reads vitreous on Gillardite and adamantine to vitreous on Clinoatacamite.
All properties
- Chemical formula
- Cu₃Ni(OH)₆Cl₂
- Mohs hardness
- 3
- Density
- 3.76 g/cm³
- Colors
- Streak
- Green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Aggregates, triangular crystals
- Cleavage
- Good on {10*1}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In silicified ferruginous gossan developed on a komatiite-hosted sulfide deposit
Where rockhounds find gillardite
Classic worldwide localities
- 132 North deposit, Widgiemooltha, Western Australia, Australia (type locality)
Field-hunting tip
Where it forms: In silicified ferruginous gossan developed on a komatiite-hosted sulfide deposit. If you start seeing ni-bearing clinoatacamite in float, you are in the right ground. Typical habit: aggregates, triangular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find gillardite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
