Powder technology and sintering were used to transform a heavy metal containing vitrified municipal incinerator fly ash into glass ceramic products. Highly crystalline and dense products (>95% theoretical density) were fabricated developing an optimised heat treatment in order to influence the crystallisation and densification kinetics of powder compacts. The best fabricated glass ceramic samples were sintered for 6 h at 1000°C after a holding time of 4 h at 880°C. They exhibited a microstructure composed mainly of elongated crystals of pyroxene type in a residual glassy matrix. The remaining porosity was low and limited to small isolated pores. The material showed attractive mechanical properties, i.e. relatively high fracture strength and toughness, very low brittleness index and relatively high thermal shock resistance. The products have a large application potential especially as construction and building materials. As shown in this study some open questions concerning the chemical durability and toxicity of the products remain, however, and they must be fully answered before these glass ceramics can be realistically considered for the envisaged applications.