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 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: white, gray white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: irregular grains.
Often confused with
Paracostibite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Paracostibite is noticeably harder (Mohs 7 vs. 5.5); streak differs, so Paracostibite leaves black, Cobaltite leaves grayish black.
How to tell apart: Paracostibite is noticeably harder (Mohs 7 vs. 5.5); streak differs, so Paracostibite leaves black, Gersdorffite leaves grayish black.
How to tell apart: Paracostibite is noticeably harder (Mohs 7 vs. 5-5.5); streak differs, so Paracostibite leaves black, Ullmannite leaves grayish black.
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
- 7
- Density
- 6.9 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Irregular grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In drill core from a massive base-metal sulfide deposit in a carbonatized chlorite-anthophyllite schist that is most likely an altered mafic rock, in a sequence of metavolcanics and metasediments (Trout Bay, Canada)
Where rockhounds find paracostibite
Classic worldwide localities
- Drill core from Trout Bay, 32 km west of Red Lake, Kenora district, Ontario, Canada (type locality)
- Wheal Cock, Botallack, St. Just, Cornwall, England
- Gruvåsen and Getön deposits, Bergslagen metallic province, Sweden
Field-hunting tip
Where it forms: In drill core from a massive base-metal sulfide deposit in a carbonatized chlorite-anthophyllite schist that is most likely an altered mafic rock, in a sequence of metavolcanics and metasediments (Trout Bay, Canada). If you start seeing sphalerite, chalcopyrite, galena in float, you are in the right ground. Typical habit: irregular grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify paracostibite?+
Where is paracostibite found?+
Is paracostibite safe to handle?+
What rocks look like paracostibite?+
What minerals are found with paracostibite?+
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Find paracostibite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
