Karpenkoite is a rare cobalt vanadate, typically orange. Associated minerals include martyite, quartz and gypsum. It was first described from Little Eva mine, Yellow Cat District, Grand County, Utah, USA.
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 ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: orange.
- 5Look at form & habitCrystal system: trigonal. 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, so Karpenkoite leaves pale yellow-orange, Chrysotile leaves white; luster reads vitreous on Karpenkoite and silky on Chrysotile.
How to tell apart: Streak differs, so Karpenkoite leaves pale yellow-orange, Lizardite leaves white; luster reads vitreous on Karpenkoite and waxy on Lizardite.
How to tell apart: Streak differs, so Karpenkoite leaves pale yellow-orange, Antigorite leaves white; luster reads vitreous on Karpenkoite and resinous, greasy, silky, waxy, earthy 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
- Co₃(V₂O₇)(OH)₂·2H₂O
- Mohs hardness
- ~3
- Density
- 3.415 g/cm³
- Colors
- Streak
- Pale yellow-orange
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Platy crystals, pseudohexagonal scales
- Cleavage
- Perfect on {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed during the post-mining oxidation of corvusite and montroseite in a moist environment at ambient temperatures
Where rockhounds find karpenkoite
Classic worldwide localities
- Little Eva mine, Yellow Cat District, Grand County, Utah, USA
Field-hunting tip
Where it forms: A secondary mineral formed during the post-mining oxidation of corvusite and montroseite in a moist environment at ambient temperatures. If you start seeing martyite, quartz, gypsum in float, you are in the right ground. Typical habit: platy crystals, pseudohexagonal scales. 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.
