Paracostibite is a rare cobalt antimony sulfide mineral that occurs primarily as metallic, anhedral grains within hydrothermal veins. It is frequently associated with other cobalt-nickel arsenides and sulfides, often requiring microscopic analysis or X-ray diffraction for definitive identification in the field.
Is this paracostibite?
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 paracostibite with a known reference. Paracostibite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Paracostibite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Paracostibite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, anhedral grains.
Often confused with
Paracostibite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Cobaltite is the harder of the two (Mohs 5.5 vs. 3.5-4); streak differs, so Paracostibite leaves black, Cobaltite leaves greyish-black.
How to tell apart: Gersdorffite is the harder of the two (Mohs 5.5 vs. 3.5-4); streak differs, so Paracostibite leaves black, Gersdorffite leaves grayish-black.
How to tell apart: Ullmannite is the harder of the two (Mohs 5-5.5 vs. 3.5-4).
Often found alongside paracostibite
Minerals reported to co-occur with paracostibite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoSbS
- Mohs hardness
- 3.5-4
- Density
- 7.3 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-200 per specimen
Where rockhounds find paracostibite
Classic worldwide localities
- Cobalt, Ontario, Canada
- Tunaberg, Sweden
- Stephansberg, Germany
Field-hunting tip
Look in hydrothermal veins country, the host setting where paracostibite typically forms. If you start seeing cobaltite, skutterudite, nickeline in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find paracostibite on the map
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