The effect of quenching in air on the microstructure and the mechanical properties of the fly ash-based glass-ceramic samples were investigated. SEM observations clearly revealed that the presence of homogeneously dispersed tiny crystallites and crystalline grain size which increased with holding time at the nucleation stage. Furthermore, extensive cracks on the surface of the glass-ceramics were present due to quenching in air. On the other hand, XRD analyses clearly showed that the only crystalline phase that observed was diopside [Ca(Mg, Al)(Si, Al)(2)O-6]. The result of the Vickers microhardness tests indicated that the hardness values of the fly ash-based glass-ceramics decreased with increasing holding time at the nucleation temperature. Resistance to wear decreased with the increase in crystalline grain size, similar to hardness values.