Hibonite is an extremely rare calcium aluminum oxide mineral primarily known for its occurrence in calcium-aluminum-rich inclusions within carbonaceous chondrite meteorites. On Earth, it is found in high-grade metamorphic rocks and is prized by serious collectors and researchers for its complex chemistry and extraterrestrial origins.
Is this hibonite?
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 hibonite with a known reference. Hibonite sits at Mohs 7.5-8, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black, reddish brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic.
Often confused with
Hibonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Corundum is the harder of the two (Mohs 9 vs. 7.5-8); streak differs, so Hibonite leaves brown, Corundum leaves white; luster reads vitreous on Hibonite and adamantine to vitreous; pearly on partings on Corundum.
How to tell apart: Hibonite is noticeably harder (Mohs 7.5-8 vs. 5.5-6.5); streak differs, so Hibonite leaves brown, Magnetite leaves black; luster reads vitreous on Hibonite and metallic to submetallic, may be dull on Magnetite.
Often found alongside hibonite
Minerals reported to co-occur with hibonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAl₁₂O₁₉
- Mohs hardness
- 7.5-8
- Density
- 3.84 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic
- Cleavage
- {0001}, good; parting on {1010}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In metamorphosed limestone, pyroxenite, gneiss, and granulite of the amphibolite to granulite facies; also alluvial
Where rockhounds find hibonite
Classic worldwide localities
- Esiva, near Taolan̈aro (Fort Dauphin), and near Ambindandrakemba, Madagascar
- Furura granulite complex, southwest of Mahenge, Tanzania
- Shoriya Mountains, about 400 km southeast of Novosibirsk, western Siberia, Russia
- Punalur, Kerala, India
- Noted in some carbonaceous chondrite meteorites, as Allende, Murchison
Field-hunting tip
Where it forms: In metamorphosed limestone, pyroxenite, gneiss, and granulite of the amphibolite to granulite facies; also alluvial. If you start seeing calcic plagioclase, corundum, spinel in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hibonite?+
Where is hibonite found?+
Is hibonite safe to handle?+
What rocks look like hibonite?+
What minerals are found with hibonite?+
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Find hibonite on the map
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