Natrochalcite is a striking emerald-green secondary mineral typically found in the oxidized zones of copper ore bodies. It most commonly occurs as distinct tabular crystals or as thin, crusty coatings associated with other sulfates in arid climates.
Is this natrochalcite?
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 natrochalcite with a known reference. Natrochalcite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale greenish.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: emerald green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous.
Often confused with
Natrochalcite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside natrochalcite
Minerals reported to co-occur with natrochalcite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCu₂(SO₄)₂(OH)·H₂O
- Mohs hardness
- 4.5
- Density
- 3.49 g/cm³
- Colors
- Streak
- Pale greenish
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous
- Cleavage
- On {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral typically formed in an arid climate in the oxidized zone of copper deposits
Where rockhounds find natrochalcite
Classic worldwide localities
- Chuquicamata, at the Fortuna mine, east of Baquedano, and from the Santiagina mine, Sierra Gorda, southwest of Calama, Antofagasta, Chile
- Capo Calamita, Elba, Italy
Field-hunting tip
Where it forms: A rare mineral typically formed in an arid climate in the oxidized zone of copper deposits. If you start seeing kröhnkite, antlerite, brochantite in float, you are in the right ground. Typical habit: fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify natrochalcite?+
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What rocks look like natrochalcite?+
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Find natrochalcite on the map
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