Kolwezite is a rare copper-cobalt carbonate mineral named after its type locality in the Kolwezi mining district. It is typically found as crusts or botryoidal masses in the oxidized zones of copper deposits, often showing a distinctive light to medium green color.
Is this kolwezite?
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 kolwezite with a known reference. Kolwezite sits at Mohs ~4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: beige.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: beige brown, green, black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: encrustations, nodular.
Often confused with
Kolwezite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Kolwezite is noticeably harder (Mohs ~4 vs. 1-2); streak differs, so Kolwezite leaves beige, Aurichalcite leaves light blue; luster reads vitreous on Kolwezite and silky to pearly on Aurichalcite.
How to tell apart: Streak differs, so Kolwezite leaves beige, Malachite leaves pale green; luster reads vitreous on Kolwezite and adamantine to vitreous; silky if fibrous; dull to earthy if massive on Malachite.
How to tell apart: Kolwezite is noticeably harder (Mohs ~4 vs. 2-2.5); streak differs, so Kolwezite leaves beige, Hydrozincite leaves white; luster reads vitreous on Kolwezite and pearly, silky to dull or earthy in aggregates on Hydrozincite.
Often found alongside kolwezite
Minerals reported to co-occur with kolwezite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Co)₂(CO₃)(OH)₂
- Mohs hardness
- ~4
- Density
- 3.97 g/cm³
- Streak
- Beige
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Encrustations, nodular
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon secondary mineral in the oxidation zone of some Cu–Co hydrothermal ore deposits
Where rockhounds find kolwezite
Classic worldwide localities
- Musonoi and Kamoto Cu–Co mines, near Kolwezi, and the Mupine, and Mashamba West mines, Katanga Province, Congo (Shaba Province, Zaire)
Field-hunting tip
Where it forms: An uncommon secondary mineral in the oxidation zone of some Cu–Co hydrothermal ore deposits. If you start seeing cobaltian malachite, cobaltian dolomite, heterogenite in float, you are in the right ground. Typical habit: encrustations, nodular. Train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like kolwezite?+
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Find kolwezite on the map
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