Tongbaite is an extremely rare chromium carbide mineral typically found as microscopic grains within chromitite deposits. It is primarily sought after by advanced mineral collectors and those interested in rare chromium-bearing species. It is challenging to identify in the field and is best confirmed through laboratory X-ray diffraction analysis.
Is this tongbaite?
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 tongbaite with a known reference. Tongbaite sits at Mohs 8-9, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tongbaite leaves a dark gray streak.
- 3Read the lusterHold the specimen under a strong light. Tongbaite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: pale brownish yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: small grains, granular.
Often confused with
Tongbaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tongbaite is noticeably harder (Mohs 8-9 vs. 5.5); streak differs, so Tongbaite leaves dark gray, Chromite leaves dark brown; luster reads metallic on Tongbaite and submetallic on Chromite.
How to tell apart: Tongbaite is noticeably harder (Mohs 8-9 vs. 5.5-6); streak differs, so Tongbaite leaves dark gray, Cohenite leaves gray-black.
Often found alongside tongbaite
Minerals reported to co-occur with tongbaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cr₃C₂
- Mohs hardness
- 8-9
- Density
- 6.64 g/cm³
- Colors
- Streak
- Dark Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Small Grains, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Ultramafic Rocks
Where rockhounds find tongbaite
Classic worldwide localities
- Tongbai Mountains, Henan Province, China
- chromite deposits in ophiolites
Field-hunting tip
Look in ultramafic rocks country, the host setting where tongbaite typically forms. If you start seeing chromite, olivine, serpentine in float, you are in the right ground. Field specimens usually show a small grains, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tongbaite?+
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What rocks look like tongbaite?+
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Find tongbaite on the map
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