Figure F21. Abundance of Sc vs. MgO comparing data for Sites 1205 and 432 at Nintoku Seamount with data for Suiko Seamount (Kirkpatrick et al., 1980; M. Regelous et al., unpubl. data), Mauna Kea Volcano (Yang et al., 1996; S. Huang and F.A. Frey, unpubl. data), and mid-ocean-ridge basalt (MORB) from the East Pacific Rise (data from J.M. Sinton, pers. comm., 1998). Important observations are the lower Sc content of Hawaiian basalt relative to East Pacific Rise MORB and the decrease in Sc content with decreasing MgO at <5 wt% MgO for Nintoku lavas. Sc is a compatible element in garnet and clinopyroxene. Consequently, the difference in Sc content between Pacific MORB and Hawaiian basalt reflects the greater importance of residual garnet during the formation of Hawaiian lavas, and the decrease in Sc content at <5 wt% MgO in Nintoku lavas reflects clinopyroxene fractionation.