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. Calciopetersite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Calciopetersite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, bluish-green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular or fibrous radial sprays.
Often confused with
Calciopetersite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Calciopetersite leaves pale green, Mixite leaves white.
How to tell apart: Streak differs — Calciopetersite leaves pale green, Plagionite leaves black; 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
- CaCu₆(PO₄)₂(OH)₆·3H₂O
- Mohs hardness
- 3
- Density
- 3.8 g/cm³
- Colors
- Streak
- Pale Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular or Fibrous Radial Sprays
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Copper-lead Deposits
- Typical price
- $50-300 per specimen depending on quality and matrix
Where rockhounds find calciopetersite
Classic worldwide localities
- Touissit, Morocco
- Laurion, Greece
- Majuba Hill, Nevada, USA
Field-hunting tip
Look in oxidized copper-lead deposits country — that is the host setting where calciopetersite typically forms. If you start seeing malachite, azurite, limonite in float, you are in the right ground. Field specimens usually show a acicular or fibrous radial sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find calciopetersite on the map
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