Iolite
Trade name
Iolite is the gem-trade name for cordierite.
Photos
About Cordierite
Full reference data — crystallography, X-ray diffraction, and cited physical properties — is on the Cordierite species page.
| Formula | Mg2Al4Si5O18 |
|---|---|
| Hardness (Mohs) | 7-7.5 |
| Specific gravity | 2.6-2.66 |
| Density (calculated) | 2.613 |
| Crystal system | orthorhombic |
| Color range | blue, smoky |
| Luster | vitreous |
| Streak | white |