Abstract The present work intends to study the development of refractory aggregates from Indian magnesite by modifying the lime–silica ratio. The raw magnesite has been evaluated in terms of chemical analysis, DTA-TG, IR Spectroscopy, XRD analysis. The material has been sintered at temperatures ranging from 1550°C to 1700°C along with modification of the lime–silica ratio. The sintered material has been characterized in terms of bulk density, apparent porosity, true density, relative density, cold modulus of rupture, hot modulus of rupture, thermal shock resistance, structural properties by XRD in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by FESEM study and compositional analysis of the developed phases has been carried out by EDAX study.