A precursor for magnesium aluminum spinel powder, composed of crystalline ammonium dawsonite hydrate (NH4Al(OH)(2)CO3.H2O)and hydrotalcite (Mg6Al2(CO3)(OH)(16). 4H(2)O) phases, was synthesized via precipitation, using ammonium bicarbonate as the precipitant. The precursor was characterized by differential thermal analysis/thermogravimetry, X-rag diffractometry, and scanning electron microscopy. Reactive spinel powder, which could he densified to translucency under vacuum at 1750 degreesC in 2 h without additives, was obtained by calcining the precursor at 1100 degreesC for 2 h.