Summary: Mechanically strained, in contrast to annealed, MgO produced greater yields of forsterite and protoenstatite by solid-state reaction with a quartz-cristo-balite mixture at 1200–1400° C. The specific surfaces of the strained and of the annealed MgO were similar. The strained MgO was more hygroscopic and similarity of the surface free energies was thus unlikely. The difference in the amounts of silicates produced from the two types of MgO decreased as the temperatures of synthesis increased. This was ascribed to loss of strain energy by unavoidable annealing before and after these temperatures had been reached.
Similar results were obtained when hydrated silica was substituted for the quartz-eristobalite mixture, but more forsterite was produced.