Clinoclase is a rare and striking copper arsenate mineral highly prized by collectors for its deep, rich blue-green color. It typically forms as radiating spray-like clusters or thin tabular crystals within the oxidized zones of copper deposits.
Is this clinoclase?
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 clinoclase with a known reference. Clinoclase sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Clinoclase leaves a bluish-green streak.
- 3Read the lusterHold the specimen under a strong light. Clinoclase typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark blue, bluish-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates, crusts, or drusy coatings.
Often confused with
Clinoclase vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Clinoclase leaves bluish-green, Liroconite leaves pale blue.
How to tell apart: Streak differs — Clinoclase leaves bluish-green, Olivenite leaves olive-green; luster reads vitreous on Clinoclase and adamantine on Olivenite.
How to tell apart: Streak differs — Clinoclase leaves bluish-green, Vivianite leaves white to light blue.
Often found alongside clinoclase
Minerals reported to co-occur with clinoclase. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃AsO₄(OH)₃
- Mohs hardness
- 2.5-3
- Density
- 4.38 g/cm³
- Colors
- Streak
- Bluish-green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates, Crusts, Or Drusy Coatings
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Copper-arsenic Hydrothermal Deposits
- Typical price
- $50-500 thumbnail, $500-2000+ cabinet
Where rockhounds find clinoclase
Classic worldwide localities
- Cornwall, England
- Utah, USA
- Black Forest, Germany
- Arizona, USA
Field-hunting tip
Look in oxidized copper-arsenic hydrothermal deposits country — that is the host setting where clinoclase typically forms. If you start seeing olivenite, conichalcite, malachite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates, crusts, or drusy coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find clinoclase on the map
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