We report microprobe, instrumental neutron activation analysis, and radiochemical neutron activation analysis data for three large igneous inclusions in the Yamato (Y-)75097, Y-793241, and Y-794046 ordinary chondrites. The inclusions in the first two chondrites are troctolitic cumulates that have undergone appreciable reactions with their hosts either during emplacement and/or cooling. Olivine-spinel Fe-Mg exchange pairs in these two inclusions record equilibration temperatures of about 710¿C, and these temperatures are similar to those exhibited by mineral pairs in the Y-75097 and Y-793241 hosts. The inclusion in Y-794046 is texturally unique, consisting of fine-grained, randomly distributed olivines, coarse (~2 mm) fascicular pyroexene laths, and angular pockets of maskelynite/plagioclase feldspar. The phase compositions are readily interpreted as having resulted from extremely rapid, essentially isochemical cooling to temperatures 1670¿C. We suggest that this igneous inclusion formed in situ by shock. ¿ American Geophysical Union 1994