Wikimedia Commons

Iolite

Hardness (Mohs): 7–7.5
Chemical Formula: (Mg,Fe)2Al4Si5O18
Crystal System: Orthorhombic
Size: Specimen size varies; record the piece, not the species

Silicates

Iolite is the gem name for cordierite. It is strongly pleochroic, violet in one direction and yellow-gray in another.

This page is only for Iolite. Comments below are for this material.