Aurichalcite is a stunning secondary mineral known for its delicate, acicular crystals that often form beautiful, sky-blue tufts and crusts. Collectors treasure it for its vibrant color and intricate, radiating crystal habits, which are commonly found in the oxidized zones of base metal ore deposits.
Is this aurichalcite?
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 aurichalcite with a known reference. Aurichalcite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Aurichalcite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Aurichalcite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: pale blue, greenish-blue, sea-green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, lath-like, botryoidal crusts, tufted sprays.
Often confused with
Aurichalcite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Hemimorphite is the harder of the two (Mohs 4.5-5 vs. 2); streak differs — Aurichalcite leaves pale blue, Hemimorphite leaves white; luster reads pearly on Aurichalcite and vitreous on Hemimorphite.
How to tell apart: Malachite is the harder of the two (Mohs 3.5-4 vs. 2); streak differs — Aurichalcite leaves pale blue, Malachite leaves light green; luster reads pearly on Aurichalcite and vitreous on Malachite.
How to tell apart: Streak differs — Aurichalcite leaves pale blue, Chrysocolla leaves white; luster reads pearly on Aurichalcite and vitreous on Chrysocolla.
Often found alongside aurichalcite
Minerals reported to co-occur with aurichalcite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Zn,Cu)₅(CO₃)₂(OH)₆
- Mohs hardness
- 2
- Density
- 3.6-3.9 g/cm³
- Streak
- Pale Blue
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals, Lath-like, Botryoidal Crusts, Tufted Sprays
- Cleavage
- Perfect in One Direction
- Rarity
- Common
- Uses
- Collector
- Host rock
- Oxidized Zones of Zinc and Copper Deposits
- Typical price
- $10-150 thumbnail to cabinet size
Where rockhounds find aurichalcite
Classic worldwide localities
- Ojuela Mine, Mexico
- Kelly Mine, USA
- Laurion, Greece
- Tsumeb, Namibia
Field-hunting tip
Look in oxidized zones of zinc and copper deposits country — that is the host setting where aurichalcite typically forms. If you start seeing smithsonite, hemimorphite, hydrozincite in float, you are in the right ground. Field specimens usually show a acicular crystals, lath-like, botryoidal crusts, tufted sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find aurichalcite on the map
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