Domeykite is a metallic copper arsenide typically found as massive or botryoidal aggregates that tarnish to a dull yellowish color over time. It is easily identified by its high density and metallic luster, often occurring alongside native copper in hydrothermal veins. Collectors should handle this mineral with caution due to its arsenic content.
Is this domeykite?
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 domeykite with a known reference. Domeykite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Domeykite leaves a metallic white streak.
- 3Read the lusterHold the specimen under a strong light. Domeykite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: tin-white, silver-white, yellowish.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, botryoidal, reniform, or granular.
Often confused with
Domeykite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Domeykite leaves metallic white, Algodonite leaves white.
How to tell apart: Streak differs — Domeykite leaves metallic white, Arsenic leaves black.
How to tell apart: Nickeline is the harder of the two (Mohs 5-5.5 vs. 3-3.5); streak differs — Domeykite leaves metallic white, Nickeline leaves brownish-black.
Often found alongside domeykite
Minerals reported to co-occur with domeykite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃As
- Mohs hardness
- 3-3.5
- Density
- 7.2-7.9 g/cm³
- Streak
- Metallic White
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Botryoidal, Reniform, Or Granular
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Ore of Copper
- Host rock
- Hydrothermal Veins, Copper Deposits
- Typical price
- $20-150 thumbnail, $200+ cabinet specimen
Where rockhounds find domeykite
Classic worldwide localities
- Chañarcillo, Chile
- Mohawk Mine, Michigan, USA
- Zwickau, Germany
- Cornwall, England
Field-hunting tip
Look in hydrothermal veins, copper deposits country — that is the host setting where domeykite typically forms. If you start seeing native copper, arsenic, calcite in float, you are in the right ground. Field specimens usually show a massive, botryoidal, reniform, or granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find domeykite on the map
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