Trigodomeykite is a rare hexagonal polymorph of the copper arsenide domeykite. It is typically found in massive, metallic form and is often associated with native copper deposits where arsenic-rich fluids have interacted with primary ore zones.
Is this trigodomeykite?
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 trigodomeykite with a known reference. Trigodomeykite 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. Trigodomeykite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Trigodomeykite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, tin-white, pale yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive.
Often confused with
Trigodomeykite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Trigodomeykite leaves black, Domeykite leaves metallic white.
How to tell apart: Nickeline is the harder of the two (Mohs 5-5.5 vs. 3-3.5); streak differs — Trigodomeykite leaves black, Nickeline leaves brownish-black.
How to tell apart: Streak differs — Trigodomeykite leaves black, Algodonite leaves white.
Often found alongside trigodomeykite
Minerals reported to co-occur with trigodomeykite. 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
- 7.5-7.9 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Ore of Copper
- Host rock
- Hydrothermal Veins
- Typical price
- $20-100 per specimen
Where rockhounds find trigodomeykite
Classic worldwide localities
- Michigan, USA
- Copiapo, Chile
- Saxony, Germany
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where trigodomeykite typically forms. If you start seeing copper, cuprite, arsenic in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find trigodomeykite on the map
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