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 — Cobaltite leaves greyish-black, Skutterudite leaves black.
How to tell apart: Streak differs — Cobaltite leaves greyish-black, Arsenopyrite leaves black.
How to tell apart: Streak differs — 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 — that is 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
How do you identify cobaltite?+
Where is cobaltite found?+
Can I find cobaltite in the United States?+
How much is cobaltite worth?+
Is cobaltite safe to handle?+
What rocks look like cobaltite?+
What minerals are found with cobaltite?+
What kind of rock does cobaltite form in?+
What is cobaltite used for?+
Find cobaltite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
