Plot of Co versus Sm (after Steele et al., 1992) showing (a) all holohyaline beads from the 74220 and 15426 samples analyzed in this study; (b) region of the Co-Sm plot with only 15426 holohyaline bead centers shown and fields for groupings of A, B, C glasses from Steele et al. (1992) shown. These authors introduced two subgroups for the B type beads, iB (lower Sm) and hB (higher Sm).