Crystalline forsterite grain formation due to the coalescence growth of MgO and SiO2 smoke particles

Experimental studies of coalescence between MgO grains and SiO2 grains in smoke reveal the direct production of crystalline forsterite grains and amorphous Mg-bearing silicate owing to the difference of cooling velocity after the formation of Mg2SiO4 (forsterite) grains. This result suggests the observed crystalline Mg2SiO4 grains and amorphous Mg-bearing silicate in RSG, AGB, post-AGB and PNe were produced by the coalescence growth between MgO and SiO2 grains or Mg and SiO grains.