Figure F11. Primitive glasses (Mg# > 60%) from the 14°–16°N region of the Mid-Atlantic Ridge (Melson et al., 1977; C. Xia et al., unpubl. data) extend to >52 wt% SiO₂ and are among the most SiO₂-rich primitive glasses that have been recovered from the mid-ocean ridges. Mid-ocean-ridge glass data, including data from the Melson et al. catalog, were downloaded in April 2003 from PetDB (online at petdb.ldeo.columbia.edu/petdb/).