Karpenkoite is a very rare cobalt-bearing member of the serpentine group. It is typically found as small, dark green platy crystals forming on oxidized cobalt-rich ore deposits and is highly sought after by systematic mineral collectors.
Is this karpenkoite?
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 karpenkoite with a known reference. Karpenkoite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Karpenkoite leaves a light green streak.
- 3Read the lusterHold the specimen under a strong light. Karpenkoite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, blackish green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, pseudohexagonal scales.
Often confused with
Karpenkoite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Karpenkoite leaves light green, Chrysotile leaves white; luster reads vitreous on Karpenkoite and silky on Chrysotile.
How to tell apart: Streak differs — Karpenkoite leaves light green, Lizardite leaves white; luster reads vitreous on Karpenkoite and greasy on Lizardite.
How to tell apart: Streak differs — Karpenkoite leaves light green, Antigorite leaves white; luster reads vitreous on Karpenkoite and greasy on Antigorite.
Often found alongside karpenkoite
Minerals reported to co-occur with karpenkoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Co₆(Si₄O₁₀)(OH)₈
- Mohs hardness
- 2-3
- Density
- 2.66 g/cm³
- Colors
- Streak
- Light Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Pseudohexagonal Scales
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Cobalt-rich Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find karpenkoite
Classic worldwide localities
- Aidyrlya ore deposit, Russia
Field-hunting tip
Look in oxidized zones of cobalt-rich deposits country — that is the host setting where karpenkoite typically forms. If you start seeing quartz, goethite, hematite in float, you are in the right ground. Field specimens usually show a platy crystals, pseudohexagonal scales habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find karpenkoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
