Figure F23. Glasses from the 14° to 16°N region of the Mid-Atlantic Ridge (Melson et al., 1977; C. Xia et al., unpubl. data) have a minimum Mg# = ~50%. Glasses with Mg#s < 50% are rare along the Mid-Atlantic Ridge. Mid-ocean-ridge glass data, including data from the Melson et al., Smithsonian catalog, were downloaded in April 2003 from PetDB (online at petdb.ldeo.columbia.edu/petdb/).