Using a gas -jet levitator, Mg -silicate glasses containing forsterite (Mg 2 SiO 4 ) or enstatite (MgSiO 3 ) are obtained, -jet. It can transform the levitated droplets into crystals or glass during cooling. The critical cooling rate for glass formation (R c ) for levitated Mg -silicate melts ( 10 -1 -10 2 K/s) is considerably lower than that for non -levitated melts (>10 3 K/s) because of the inhibition of crystallization by the sample holder in the former. Furthermore, the crystallization temperature of the levitated Mg -silicate melts is very low (~ 900 °C). Chondrules in chondrites are assumed to have been formed from the melt droplets in such a levitation environment. Several researchers have concluded that R c for a chondrule melt held by a platinum wire is equal to the upper limit of the cooling rate for the chondrule melt, estimated to be ~ 1000 K/h. However, in a levitation environment, SiO 2 -rich melts do not crystallize at this cooling rate. We conclude that the previously proposed maximum cooling rate for chondrule melts has been greatly overestimated. We infer that spontaneous crystallization of a completely melted chondrule precur--tion of chondrule melts, it is necessary that the precursor of the chondrules should be partially melted or the completely melted precursor should be in contact with nebular dust.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.