Andalusite
| Colour | Brown, Green, Pink, Purple, Yellow |
|---|---|
| Mohs hardness | 6.5–7.5 |
| Lustre | Vitreous |
| Streak | White |
| Crystal system | Orthorhombic |
| Transparency | Transparent to nearly opaque with inclusions |
| Cleavage | Good on {110}, poor on {100} |
| Fracture | uneven to subconchoidal |
| Chemical formula | Al 2 SiO 5 |
| Specific gravity | 3.17 (± .04) |
What is Andalusite?
Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5. This mineral was called andalousite by Delamétherie, who thought it came from Andalusia, Spain. It soon became clear that it was a locality error, and that the specimens studied were actually from El Cardoso de la Sierra, in the Spanish province of Guadalajara, not Andalusia.
How to identify Andalusite
- Lustre: Vitreous.
- Hardness: Mohs 6.5–7.5 — hard enough to scratch glass.
- Streak: White.
- Habit: Orthorhombic crystal system.
Andalusite in different forms
Stones often confused with Andalusite
Frequently asked questions
How hard is Andalusite?
Andalusite is Mohs 6.5–7.5 on the hardness scale.
What colour is Andalusite?
Andalusite is typically brown, green, pink, purple, yellow (Pink, violet, yellow, green, white, gray; in thin section, colorless to pink or green).