  We report microscopic, cathodoluminescence, chemical and O isotopic
measurements of FeO-poor isolated olivine grains (IOG) in the carbonaceous
chondrites Allende (CV3), Northwest Africa 5958 (C2-ung), Northwest Africa
11086 (CM2-an), Allan Hills 77307 (CO3.0). The general petrographic, chemical
and isotopic similarity with bona fide type I chondrules confirms that the IOG
derived from them. The concentric CL zoning, reflecting a decrease in
refractory elements toward the margins, and frequent rimming by enstatite are
taken as evidence of interaction of the IOG with the gas as stand-alone
objects. This indicates that they were splashed out of chondrules when these
were still partially molten. CaO-rich refractory forsterites, which are
restricted to $\Delta^{17}O < -4\permil$ likely escaped equilibration at lower
temperatures because of their large size and possibly quicker quenching. The
IOG thus bear witness to frequent collisions in the chondrule-forming regions.
