Calciopetersite is a rare secondary mineral typically found as delicate, needle-like crystals or sprays within oxidized base-metal deposits. It is best identified by its vibrant green color and association with other secondary copper minerals in weathered mine dumps.
Is this calciopetersite?
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 calciopetersite with a known reference. Calciopetersite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light olive-green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: olive green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular, radial.
Often confused with
Calciopetersite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Calciopetersite leaves light olive-green, Mixite leaves pale bluish green.
How to tell apart: Streak differs, so Calciopetersite leaves light olive-green, Plagionite leaves blackish lead-gray, deep red-brown; luster reads vitreous on Calciopetersite and metallic on Plagionite.
Often found alongside calciopetersite
Minerals reported to co-occur with calciopetersite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆Ca(PO₄)₂(PO₃OH)(OH)₆·3H₂O
- Mohs hardness
- 3
- Density
- 3.179 g/cm³
- Colors
- Streak
- Light olive-green
- Luster
- Vitreous
- Transparency
- Translucent to transparent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular, radial
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral derived by weathering chalcopyrite and other copper sulfides
Where rockhounds find calciopetersite
Classic worldwide localities
- An abandoned quarry near Domašov nad Bystřicí, 20 km northeast of Olomouc, northern Moravia, Czech Republic
- Fantoni quarry, Monte Beni, Firenzuola, Florence, Tuscany, Italy
Field-hunting tip
Where it forms: A secondary mineral derived by weathering chalcopyrite and other copper sulfides. If you start seeing chrysocolla, malachite, allophane in float, you are in the right ground. Typical habit: acicular, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calciopetersite?+
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What rocks look like calciopetersite?+
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Find calciopetersite on the map
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