Devilline is a striking secondary copper mineral that typically forms delicate, fan-shaped clusters of bright blue to greenish-blue platy crystals. It is most commonly found in the oxidation zones of sulfide ore deposits, often appearing as coatings on other copper minerals like malachite or azurite. Because of its fragile nature and solubility, it is highly prized by mineral collectors who appreciate its vivid color and unique crystal habits.
Is this devilline?
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 devilline with a known reference. Devilline sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Devilline leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Devilline typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, greenish-blue, emerald-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, fan-like aggregates, tufts.
Often confused with
Devilline vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside devilline
Minerals reported to co-occur with devilline. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCu₄(SO₄)₂(OH)₆·3H₂O
- Mohs hardness
- 2.5
- Density
- 3.2 g/cm³
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts, Fan-like Aggregates, Tufts
- Cleavage
- Perfect On {001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Oxidized Zones of Copper Deposits
- Typical price
- $10-150 thumbnail, $200+ cabinet specimen
Where rockhounds find devilline
Classic worldwide localities
- Herrengrund, Slovakia
- Cornwall, England
- Chessy-les-Mines, France
- Bisbee, Arizona, USA
- Laurion, Greece
Field-hunting tip
Look in oxidized zones of copper deposits country — that is the host setting where devilline typically forms. If you start seeing malachite, azurite, brochantite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, fan-like aggregates, tufts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find devilline on the map
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