Goudeyite is a rare copper-aluminum arsenate mineral that typically forms vibrant, needle-like tufts or crusts in oxidized copper zones. It is highly sought after by micromounters and mineral collectors due to its intense color and delicate crystal habits, often appearing as distinct yellow-green or green sprays.
Is this goudeyite?
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 goudeyite with a known reference. Goudeyite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, yellow green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular, hexagonal.
Often confused with
Goudeyite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside goudeyite
Minerals reported to co-occur with goudeyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆Al(AsO₄)₃(OH)₆·3H₂O
- Mohs hardness
- 3-4
- Density
- 3.50 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular, hexagonal
- Cleavage
- Perfect on {100}; good on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in a hydrothermal Cu–Sn orebody in rhyolite porphyries and breccias (Majuba Hill, Nevada, USA)
Where rockhounds find goudeyite
Classic worldwide localities
- Majuba Hill mine, Antelope district, Pershing Co., Nevada, USA
- Virneberg mine, near Rheinbreitbach, Rhineland-Palatinate, Germany
- Chessy, near Lyon, Rhône, France
- Tsumeb, Namibia
Field-hunting tip
Where it forms: A rare secondary mineral in a hydrothermal Cu–Sn orebody in rhyolite porphyries and breccias (Majuba Hill, Nevada, USA). If you start seeing olivenite, clinoclase, cornwallite in float, you are in the right ground. Typical habit: acicular, hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify goudeyite?+
Where is goudeyite found?+
Is goudeyite safe to handle?+
What rocks look like goudeyite?+
What minerals are found with goudeyite?+
What kind of rock does goudeyite form in?+
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Find goudeyite on the map
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