| Chemical formula | Na2Mg3Al2Si8O22(OH)2 |
| Class | Inosilicate Double chains of linked tetrahedra |
| Crystal system | Monoclinic |
| Habit | Acicular Asbestiform Fibrous |
| Color | Blue Gray |
| Hardness | 6-6.5 |
| Specific gravity | 3.1 to 3.2 |
| Cleavage/fracture | Two perfect prismatic {110}/ uneven |
| Luster | Vitreous |
| Transparency | Transparent to translucent |
| Streak | White to very light blue |
| δ | 0.01 – 0.02 |
| PPL | Colorless to blue or violet Often strongly pleochroic |
| XPL | Up to 2nd order interference colors Interference color may be masked by mineral color |
| after Perkins, 333 |
Glaucophane in Hand Sample
Glaucophane in Turkish blueschist
Glaucophane in Greek blueschist (the two samples on the left)
Fine-grained blueschist
Medium-grained blueschist
Garnet-studded retrograde blueschist after eclogite
Glaucophane in Thin Section
