Kyanite
Kyanite is a blue silicate mineral unique for having different hardness values depending on the direction of scratch (4-5 lengthwise, 6-7 crosswise).
Kyanite properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | Al2SiO5 |
| Mohs hardness | 5 |
| Crystal system | triclinic |
| Luster | vitreous |
| Streak | White |
| Cleavage | Perfect |
| Fracture | Fibrous |
| Specific gravity | 3.6 |
| Transparency | translucent |
| Common colors | Blue, Green, Orange, Black |
| Rarity | uncommon |
Geology & background
Forms during regional metamorphism of aluminum-rich rocks under high pressure.
Important indicator mineral for geologists studying metamorphic conditions.
How to identify Kyanite
- Check whether the specimen's color and texture match typical Kyanite examples.
- Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Where Kyanite is found
Kyanite is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.
How much is Kyanite worth?
| Entry-level specimen | $10 |
|---|---|
| Typical collector specimen | $50 |
| Premium specimen | $300+ |
Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Jewelry
- High-temperature ceramics
- Collector specimens
Interesting facts
- Has two different hardnesses in perpendicular directions
- Name comes from Greek 'kyanos' meaning blue
- Used to make high-temperature ceramics and refractories
Care & safety
Treat Kyanite as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
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