Dumortierite
| Colour | Blue, Green, Purple, Red |
|---|---|
| Mohs hardness | 7–8.5 |
| Lustre | Vitreous to dull |
| Streak | White |
| Crystal system | Orthorhombic |
| Transparency | Transparent to translucent |
| Cleavage | Distinct on {100}, poor on {110}; parting on {001} |
| Fracture | Fibrous |
| Chemical formula | Al 7 BO 3 (SiO 4 ) 3 O 3 or Al 6.5-7 BO 3 (SiO 4 ) 3 (O,OH) 3 |
| Specific gravity | 3.3–3.4 |
What is Dumortierite?
Dumortierite is a fibrous variably colored aluminium boro-silicate mineral, Al7BO3(SiO4)3O3. It crystallizes in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals. The crystals are vitreous and vary in color from brown, blue, and green to more rare violet and pink. Substitution of iron and other tri-valent elements for aluminium results in the color variations. It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.4. Crystals show pleochroism from red to blue to violet. Dumortierite quartz is blue colored quartz containing abundant dumortierite
How to identify Dumortierite
- Lustre: Vitreous to dull.
- Hardness: Mohs 7–8.5 — hard enough to scratch glass.
- Streak: White.
- Habit: Orthorhombic crystal system.
Dumortierite in different forms
Stones often confused with Dumortierite
Frequently asked questions
How hard is Dumortierite?
Dumortierite is Mohs 7–8.5 on the hardness scale.
What colour is Dumortierite?
Dumortierite is typically blue, green, purple, red (Blue, greenish-blue, violet-blue, pale blue, red).