Chaoite is an extremely rare polymorph of carbon first discovered in shock-metamorphosed graphite gneiss from an impact crater. It typically occurs as white or gray microcrystalline inclusions within graphite and is distinguished from other carbon allotropes by its unique crystal structure resulting from high-pressure shock events.
Is this chaoite?
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 chaoite with a known reference. Chaoite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chaoite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Chaoite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: microcrystalline aggregates.
Often confused with
Chaoite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Chaoite leaves white, Graphite leaves black.
How to tell apart: Diamond is the harder of the two (Mohs 10 vs. 1-2); streak differs — Chaoite leaves white, Diamond leaves none; luster reads metallic on Chaoite and adamantine on Diamond.
Often found alongside chaoite
Minerals reported to co-occur with chaoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- C
- Mohs hardness
- 1-2
- Density
- 3.33 g/cm³
- Streak
- White
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Microcrystalline Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Impact Craters
- Typical price
- expensive
Where rockhounds find chaoite
Classic worldwide localities
- Bayer crater, Nördlinger Ries, Germany
- Popigai crater, Russia
- Manicouagan crater, Canada
Field-hunting tip
Look in impact craters country — that is the host setting where chaoite typically forms. If you start seeing graphite, diamond, carbonado in float, you are in the right ground. Field specimens usually show a microcrystalline aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find chaoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
