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, so 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, so Trigodomeykite leaves black, Nickeline leaves brownish-black.
How to tell apart: Streak differs, so 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, 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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