Crystallisation Of Cu-Containing K-Fluor-Richterite (Knaca(Mg,Cu)5Si8O22F2) Glasses

Gradual substitutions of Cu for Mg in K-fluor-richterite glass-ceramics were investigated. Crystallisation of Cu-free or Cu-containing glasses gave K-fluor-richterite, enstatite, diopside, forsterite, rodderite, tenorite, cuprite, fluorite and crystalline silica. Colour changes in the crystallised glasses, from blue to orange or dark brown with increasing copper indicates change of either valency or the position of copper in the glass-ceramic structure.