Nakauriite is a rare hydrated copper sulfate-carbonate that typically forms as soft, sky-blue fibrous crusts or tiny needle-like aggregates. It is almost exclusively found in association with serpentinite environments, often appearing as an alteration product of primary ore minerals.
Is this nakauriite?
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 nakauriite with a known reference. Nakauriite sits at Mohs 2-3, 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: dull.
- 4Match the color rangeCompare against the expected color range: sky blue, light blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, fibrous, microscopic crystals.
Often confused with
Nakauriite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull on Nakauriite and vitreous, porcelaneous, earthy on Chrysocolla.
How to tell apart: Streak differs, so Nakauriite leaves white, Langite leaves greenish blue; luster reads dull on Nakauriite and vitreous to silky on Langite.
Often found alongside nakauriite
Minerals reported to co-occur with nakauriite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₈(SO₄)₄(CO₃)(OH)₆·48H₂O
- Mohs hardness
- 2-3
- Density
- 2.39 g/cm³
- Colors
- Streak
- White
- Luster
- Dull
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, fibrous, microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As fracture fillings in serpentinite (Nakauri, Japan); on chromatite from serpentinite (Hagdale quarry, Scotland)
Where rockhounds find nakauriite
Classic worldwide localities
- Gabbs mine, Gabbs district, Nye Co., Nevada, USA
- Cedar Hill quarry, Lancaster Co., Pennsylvania, USA
- An abandoned mine at Nakauri, about 6 km southeast of Shinshiro, Aichi Prefecture, Japan
- Hagdale quarry, Unst, Shetland Islands, Scotland
Field-hunting tip
Where it forms: As fracture fillings in serpentinite (Nakauri, Japan); on chromatite from serpentinite (Hagdale quarry, Scotland). If you start seeing chrysotile, magnetite, artinite in float, you are in the right ground. Typical habit: acicular, fibrous, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nakauriite?+
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What rocks look like nakauriite?+
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Find nakauriite on the map
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