Plancheite is a beautiful, distinctively fibrous copper silicate that often forms stunning botryoidal or tufted masses. Collectors prize it for its vibrant sky-blue to deep-blue coloration and its association with other secondary copper minerals in oxidized ore zones.
Is this plancheite?
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 plancheite with a known reference. Plancheite sits at Mohs 5.5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Plancheite leaves a light blue streak.
- 3Read the lusterHold the specimen under a strong light. Plancheite typically shows a silky luster.
- 4Match the color rangeCompare against the expected color range: blue, light blue, dark blue, greenish-blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: botryoidal, fibrous, acicular aggregates.
Often confused with
Plancheite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Plancheite is noticeably harder (Mohs 5.5-6 vs. 2-4); streak differs — Plancheite leaves light blue, Chrysocolla leaves white; luster reads silky on Plancheite and vitreous on Chrysocolla.
How to tell apart: Streak differs — Plancheite leaves light blue, Hemimorphite leaves white; luster reads silky on Plancheite and vitreous on Hemimorphite.
How to tell apart: Plancheite is noticeably harder (Mohs 5.5-6 vs. 3.5-4); luster reads silky on Plancheite and vitreous to dull on Azurite.
Often found alongside plancheite
Minerals reported to co-occur with plancheite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₈Si₈O₂₂(OH)₄·H₂O
- Mohs hardness
- 5.5-6
- Density
- 3.37 g/cm³
- Streak
- Light Blue
- Luster
- Silky
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Botryoidal, Fibrous, Acicular Aggregates
- Cleavage
- Good
- Rarity
- Uncommon
- Uses
- Collector, Decorative
- Host rock
- Oxidized Zones of Copper Ore Deposits
- Typical price
- $15-150 thumbnail, $50-400 cabinet
Where rockhounds find plancheite
Classic worldwide localities
- Katanga Copper Crescent (DR Congo)
- Namibia
- Arizona (USA)
Field-hunting tip
Look in oxidized zones of copper ore deposits country — that is the host setting where plancheite typically forms. If you start seeing chrysocolla, malachite, dioptase in float, you are in the right ground. Field specimens usually show a botryoidal, fibrous, acicular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find plancheite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
