Euchroite is a rare hydrated copper arsenate known for its striking emerald-green, prismatic crystals. It is most famously found in the oxidation zones of copper deposits in Ľubietová, Slovakia, often appearing as attractive radiating sprays or individual distinct prisms.
Is this euchroite?
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 euchroite with a known reference. Euchroite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: emerald green, leek green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crystalline, druse.
Often confused with
Euchroite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Euchroite leaves green, Olivenite leaves olive-green to brown; luster reads vitreous on Euchroite and adamantine to vitreous, pearly to silky if fibrous on Olivenite.
How to tell apart: Streak differs, so Euchroite leaves green, Adamite leaves white.
Often found alongside euchroite
Minerals reported to co-occur with euchroite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂AsO₄(OH)·3H₂O
- Mohs hardness
- 3.5-4
- Density
- 3.44 g/cm³
- Colors
- Emerald greenLeek green
- Streak
- Green
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crystalline, druse
- Cleavage
- {101}, {110}, interrupted
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare mineral in the oxidized zone of some copper-bearing hydrothermal mineral deposits
Where rockhounds find euchroite
Classic worldwide localities
- Black Pine mine, Philipsburg, Granite Co., and along Cramer Creek, Missoula Co., Montana, USA
- Monte Cristo mine, Weden Creek, Snohomish Co., Washington, USA
- Sterling Hill, Ogdensburg, Sussex Co., New Jersey, USA
- L’ubietová, near Baňská Bystrica (Libethen, near Neusohl), Slovakia
- Laurium, Greece, in slag
- Zapachitsa copper deposit, Ismerez, Stara-Planina, Bulgaria
Field-hunting tip
Where it forms: A very rare mineral in the oxidized zone of some copper-bearing hydrothermal mineral deposits. If you start seeing olivenite, strashimirite, azurite in float, you are in the right ground. Typical habit: crystalline, druse. Train your eye for that shape before scanning the outcrop.
Common questions
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Find euchroite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
