We have determined the mode and phase chemistry of the 20- 10&mgr;m soil fraction for three levels in the Apollo 17 drill core and compared them to the >20&mgr;m fraction. The results indicate that the 20- 10&mgr;m fraction is enriched in Al2O3-rich clear glass and to a minor extent in olivine and depleted in pyroxene and ilmenite relative to the >20&mgr;m fraction. Plagioclase and pyroxene of highland-type compositions are relatively more abundant in the 20- 10&mgr;m fraction as well. These contrasts in mode and phase chemistry explain the enrichment in Al2O3 and depletion in FeO and TiO2 in the <20&mgr;m fraction which are observed in bulk chemical analyses of soil fractions. The contribution of highland-derived material increases with decreasing grain size. Highland material contributes 14% to 30% to the mode of the fused soil-free 200- 20&mgr;m fraction, but 25% to 55% of the fused soil-free 20- 10&mgr;m fraction. The enrichment of highland-derived material in the finer size fractions can be explained by the finer grain-size distribution of the more mature highland soil derived from the local massifs. A more effective transport of finer-grained particles may also contribute to this enrichment but we have no compelling evidence for this effect at the present time.