COMMENT Richard L. Hervig, Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1704 Drury and van Roermund (1988) reported the observation by trans-mission electron microscopy of Fe-Ti-rich multiphase microinclusions in olivines from hot, deformed garnet Iherzolites found in kimberlite. They suggested that this is caused by infiltration metasomatism, and that micro-probe analyses of these olivines, which show high trace-element contents, are not indicating the solid-solution components in olivine in equilibrium with coexisting orthopyroxene, clinopyroxene, and garnet. It is agreed that trace-element enrichment probably resulted from an enrichment event(s), and that the observed chemistry is probably not representative of the upper mantle. However, the chemistry of these olivines represents an equilibrium relation with the other phases; thus, the textures observed by Drury and van Roermund (1988) are best explained as exsolution phenomena that occurred some time after enrichment and homogenizatio the phasesn of . A compilation of trace-element chemistry (as determined by electron-and ion-probe microbeam analytical techniques) in several types of mantle-derived nodules was given in Hervig et al. (1986). They showed that the olivines from hot, deformed (HD) garnet Iherzolites generally stand out from other upper-mantle olivines. Among the HD samples are the highest AI2O3, V2O3, and Na20 contents of any olivine, and they commonly show the highest concentrations of Ti, Cr, Sc, and Li. I empha-size that this increase is not arbitrary from sample to sample, but is in consonance with the chemistry of coexisting phases. The electron- and ion-probe analyses were made on 20-30 ij.m spots and most likely over-lapped on the multiphase microinclusions. These inclusions show a bimo-dal size distribution: <0.05 ^m and 0.2-1 /?m (Drury and van Roermund, 1988). The microbeam analyses presumably represent a random mixture of olivine and inclusions. Iron Contents The iron content of phases from HD garnet Iherzolites is generally higher than in undeformed, cooler garnet Iherzolites. However, the Fe-Mg relations between the HD minerals are those expected for an equilibrium assemblage, and a geothermometer based on Fe-Mg exchange between olivine and garnet gives temperatures in general agreement with the more commonly used two-pyroxene geothermometer (see review by Finnerty and Boyd, 1984). Sodium, Chromium, Aluminum, Vanadium, and Scandium A metasomatic event might not add enough iron to change signifi-cantly the composition of the minerals in garnet lherzolite, so it is more revealing to study the trace-element composition of these phases. Not only is the Na content of HD olivine high (up to 400 ppm Na20), but also the orthopyroxenes show up to 0.4 wt% Na20, significantl higher thay n typi-cal low-temperature garnet lherzolite orthopyroxene. Hervig and Smith (1980) discovered that the logarithm of the molar ratio (Na20