Cobaltite is a distinctive cobalt-arsenic sulfide mineral often found in brilliant silver-white or reddish-tinted metallic crystals. Collectors typically look for its sharp pseudocubic habit, though it is frequently found in massive or granular forms associated with other metallic sulfides.
Is this cobaltite?
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 cobaltite with a known reference. Cobaltite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cobaltite leaves a greyish-black streak.
- 3Read the lusterHold the specimen under a strong light. Cobaltite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, reddish-white, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: pseudocubic crystals, pyritohedrons, massive, granular.
Often confused with
Cobaltite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cobaltite leaves greyish-black, Skutterudite leaves black.
How to tell apart: Streak differs, so Cobaltite leaves greyish-black, Arsenopyrite leaves black.
How to tell apart: Streak differs, so Cobaltite leaves greyish-black, Pyrite leaves greenish-black to brownish-black.
Often found alongside cobaltite
Minerals reported to co-occur with cobaltite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoAsS
- Mohs hardness
- 5.5
- Density
- 6.3 g/cm³
- Streak
- Greyish-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Pseudocubic Crystals, Pyritohedrons, Massive, Granular
- Cleavage
- Perfect On {001}
- Rarity
- Uncommon
- Uses
- Collector, Ore of Cobalt
- Host rock
- Hydrothermal Veins, Contact Metamorphic Deposits
- Typical price
- $20-150 for thumbnail to cabinet specimens
Where rockhounds find cobaltite
1 mapped spotsClassic worldwide localities
- Tunaberg, Sweden
- Cobalt, Ontario, Canada
- Bou Azzer, Morocco
- Skutterud, Norway
Field-hunting tip
Look in hydrothermal veins, contact metamorphic deposits country, the host setting where cobaltite typically forms. If you start seeing arsenopyrite, chalcopyrite, magnetite in float, you are in the right ground. Field specimens usually show a pseudocubic crystals, pyritohedrons, massive, granular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming. Start trip planning there.
Common questions
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Find cobaltite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
