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 8.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark gray.
- 3Read the lusterHold the specimen under a strong light. Luster: strong metallic.
- 4Match the color rangeCompare against the expected color range: light 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 8.5 vs. 5.5); streak differs, so Tongbaite leaves dark gray, Chromite leaves brown; luster reads strong metallic on Tongbaite and metallic to submetallic on Chromite.
How to tell apart: Tongbaite is noticeably harder (Mohs 8.5 vs. 5.5-6); streak differs, so Tongbaite leaves dark gray, Cohenite leaves gray-black; luster reads strong metallic on Tongbaite and metallic on Cohenite.
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
- 8.5
- Density
- 6.64 g/cm³
- Colors
- Light brownish yellow
- Streak
- Dark gray
- Luster
- Strong metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Small grains, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In ultramafic rocks (China)
Where rockhounds find tongbaite
Classic worldwide localities
- Liu Zhuang, Tongbai Co., Henan Province, and in the Hong district, Tibet, China
Field-hunting tip
Where it forms: In ultramafic rocks (China). If you start seeing magnesiochromite, pyrrhotite, pentlandite in float, you are in the right ground. Typical habit: small grains, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tongbaite?+
Where is tongbaite found?+
What rocks look like tongbaite?+
What minerals are found with tongbaite?+
What kind of rock does tongbaite form in?+
What is tongbaite used for?+
Find tongbaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
