Dioptase is highly prized by collectors for its stunning, intense emerald-green color and exceptional clarity. It typically forms sharp rhombohedral crystals in the oxidized zones of copper ore bodies and is quite fragile due to its perfect cleavage.
Is this dioptase?
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 dioptase with a known reference. Dioptase sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dioptase leaves a green streak.
- 3Read the lusterHold the specimen under a strong light. Dioptase typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: emerald-green, bluish-green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals, drusy, granular.
Often confused with
Dioptase vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Green Beryl is the harder of the two (Mohs 7.5-8 vs. 5); streak differs — Dioptase leaves green, Green Beryl leaves white.
How to tell apart: Dioptase is noticeably harder (Mohs 5 vs. 1.5-2); streak differs — Dioptase leaves green, Vivianite leaves white to light blue.
How to tell apart: Dioptase is noticeably harder (Mohs 5 vs. 3.5-4); streak differs — Dioptase leaves green, Brochantite leaves pale-green.
Often found alongside dioptase
Minerals reported to co-occur with dioptase. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuSiO₃·H₂O
- Mohs hardness
- 5
- Density
- 3.28-3.35 g/cm³
- Streak
- Green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic Crystals, Drusy, Granular
- Cleavage
- Perfect Rhombohedral
- Rarity
- Uncommon
- Uses
- Collector, Decorative
- Host rock
- Oxidized Zones of Copper Deposits
- Typical price
- $20-100 thumbnail, $200-2000 cabinet specimens
Where rockhounds find dioptase
1 mapped spotsClassic worldwide localities
- Tsumeb, Namibia
- Altyn-Tyube, Kazakhstan
- Arica, Chile
- Renfrew County, Ontario, Canada
Field-hunting tip
Look in oxidized zones of copper deposits country — that is the host setting where dioptase typically forms. If you start seeing malachite, chrysocolla, calcite in float, you are in the right ground. Field specimens usually show a prismatic crystals, drusy, granular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arizona — start trip planning there.
Common questions
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Find dioptase on the map
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