Iolite-Cordierite

Iolite

(Mg,Fe)2Al4Si5O18

Magnesium Iron Aluminium Cyclosilicate

Silicate Group

Orthorhombic – Dipyramidal System

Hardness: 7-7.5

Blue, smoky blue, bluish violet; greenish, yellowish brown, gray; colorless to very pale blue in thin section