Arthurite is a rare secondary copper arsenate mineral typically found in the oxidized zones of copper deposits. It usually forms small, vibrant apple-green acicular crystal sprays or coatings associated with other secondary copper minerals. Because of its rarity and striking color, it is a highly sought-after species for mineral collectors.
Is this arthurite?
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 arthurite with a known reference. Arthurite 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. Arthurite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Arthurite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: apple-green, yellow-green, emerald-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular crystals, lath-like, globular, crusts.
Often confused with
Arthurite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside arthurite
Minerals reported to co-occur with arthurite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂Fe³⁺(AsO₄,PO₄,SO₄)₂(OH)₂·4H₂O
- Mohs hardness
- 3-4
- Density
- 3.32 g/cm³
- Streak
- Pale Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Lath-like, Globular, Crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Copper-arsenic Veins
- Typical price
- $50-500 depending on specimen quality and rarity of locality
Where rockhounds find arthurite
Classic worldwide localities
- Huel Gorland, Cornwall, England
- Mapimi, Durango, Mexico
- Rudabánya, Hungary
- Black Pine mine, Montana, USA
Field-hunting tip
Look in oxidized hydrothermal copper-arsenic veins country — that is the host setting where arthurite typically forms. If you start seeing clinoclase, olivenite, conichalcite in float, you are in the right ground. Field specimens usually show a acicular crystals, lath-like, globular, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify arthurite?+
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Find arthurite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
