Rouaite is a very rare copper nitrate mineral typically found as small, dark green to bluish green tabular crystals or crusts. It is named after its type locality, the Roua copper mine in France, where it forms in oxidized zones of copper-rich ores.
Is this rouaite?
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 rouaite with a known reference. Rouaite 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. Rouaite leaves a green streak.
- 3Read the lusterHold the specimen under a strong light. Rouaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, bluish green, emerald-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, crusts, radial aggregates.
Often confused with
Rouaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Rouaite is noticeably harder (Mohs 3 vs. 2); streak differs, so Rouaite leaves green, Gerhardtite leaves light green.
How to tell apart: Streak differs, so Rouaite leaves green, Malachite leaves light green.
How to tell apart: Streak differs, so Rouaite leaves green, Connellite leaves pale blue.
Often found alongside rouaite
Minerals reported to co-occur with rouaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂(NO₃)(OH)₃
- Mohs hardness
- 3
- Density
- 3.51 g/cm³
- Streak
- Green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Crusts, Radial Aggregates
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Copper-bearing Sedimentary Rocks
Where rockhounds find rouaite
Classic worldwide localities
- Roua Copper Mine, Daluis, France
Field-hunting tip
Look in copper-bearing sedimentary rocks country, the host setting where rouaite typically forms. If you start seeing gerhardtite, brochantite, calcite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rouaite on the map
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