This research used samples and/or data provided by the Ocean Drilling Program (ODP). The U.S. National Science Foundation (NSF) sponsors ODP and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. Funding for this research was provided by a grant awarded to D.J. Miller from the U.S. Science Support Program (www.usssp-iodp.org/). We are grateful to Ray Guillemette for his time in running the microprobe and detailed discussions about microprobe analysis of volcanic glass samples. We also gratefully acknowledge Shanaka de Silva and Wolfgang Bach for their critical and constructive reviews of the paper. We also thank Lorri Peters for editing this paper.