<p>Sintering behaviour of nanocrystallites of chemically pure stoichiometric magnesium aluminate spinel (spinel) prepared by co-precipitation has been studied by using α-Al₂O₃ (corundum) as additive. α-Al₂O₃ during classical sintering of spinel at 1650°C does not form any low melting compound or second phase because of its solid-solution with spinel and its retention in spinel structure during furnace cooling to room temperature. This causes cation vacancies in spinel structure and does not hinder densification with controlled microstructure. Density, porosity, shrinkage, etc. at 1450-1650°C have been studied with 1 to 10 wt% additions of α-Al₂O₃. XRD and SEM reveal no precipitation of α-Al₂O₃ during cooling and development of similar type spinel based microstructures irrespective of α-Al₂O₃ additions at 1650°C. At 1650°C, ~99%ρ_th is achieved with addition of 1 wt% α-Al₂O₃ as compared to ~98%ρ_th without addition. Measured true specific gravity (T.S.G) of sintered pellets with α-Al₂O₃ addition by pycnometric method was close to calculated data from XRD studies determined using MgAl₂O₄-alumina solid solution mathematical frame.</p> Graphical Abstract <p></p>