Cr 2 O 3 -nucleated fine grained mono-mineral glass-ceramics of augite were produced from low-silica fly ash and additives of SiO 2 , Al 2 O 3 and MgCO 3 , via two steps of heat treatment for nucleation and crystal growth. The starting glass approached the composition of CaMg 0.75 Al 0.4 Fe 0.1 Si 1.75 O 6 , derived from CaMg 0.75 Al 0.5 Si 1.75 O 6 , which belongs to diopside – Ca-Tschermak solid solutions. The influence of Cr 2 O 3 (up to 0.75wt.%) on the development of crystalline phases, the properties and the microstructure of the resultant glass-ceramics crystallized at different temperatures was investigated.