Langisite is a rare cobalt-nickel arsenide mineral known almost exclusively from its type locality at the Langis Mine in Ontario. It typically appears as metallic, pinkish-white to brassy grains within massive arsenide ore. It is highly sought after by collectors of rare cobalt-arsenic minerals.
Is this langisite?
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 langisite with a known reference. Langisite sits at Mohs 6-6.5, 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: pink, reddish gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: anhedral grains, inclusions.
Often confused with
Langisite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Langisite leaves black, Nickeline leaves pale brownish black.
How to tell apart: Langisite is noticeably harder (Mohs 6-6.5 vs. 5); streak differs, so Langisite leaves black, Maucherite leaves blackish gray.
How to tell apart: Langisite is noticeably harder (Mohs 6-6.5 vs. 4.5-5); streak differs, so Langisite leaves black, Safflorite leaves grayish black.
Often found alongside langisite
Minerals reported to co-occur with langisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoAs
- Mohs hardness
- 6-6.5
- Density
- 8.17 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Anhedral grains, inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pockets of ore minerals, mineralized fault gouge, and breccia cemented with calcite and quartz
Where rockhounds find langisite
Classic worldwide localities
- Langis mine, Casey Township, Cobalt-Gowganda area, Ontario, Canada (type locality)
Field-hunting tip
Where it forms: In pockets of ore minerals, mineralized fault gouge, and breccia cemented with calcite and quartz. If you start seeing cobalt pentlandite, siegenite, parkerite in float, you are in the right ground. Typical habit: anhedral grains, inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
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Find langisite on the map
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