Preparation and characterization of ferromagnetic glass ceramic in the system Fe2O3 center dot CaO center dot ZnO center dot SiO2 with different nucleating agents was studied. The effect of La2O3, CoO, Cr2O3 and MoO3 as nucleating agents was investigated. Differential thermal analysis; X-ray diffraction and transmission electron microscope were used to investigate thermal behavior, sequence of crystallization and microstructure of the samples. XRD analysis for as prepared samples revealed the crystallization of single magnetite phase. Heat treatment at 900 degrees C/2 h revealed the appearance of minor amounts of calcium silicate, hematite and cristobalite beside magnetite. TEM revealed crystallization of crystallite size in the range 50-100 nm. Lattice parameters, cell volume and crystallite size were stimulated from XRD data. Magnetic properties of quenched samples were measured under 20 kG. (C) 2012 Elsevier Ltd. All rights reserved.