Geologic samples including hand samples and thin sections that were collected between 1955 and 1956 by Helen Foster and Harold May during the geologic mapping of the Pacific islands of Ryukyu that extend southwest from Japan. Most of the samples were collected from Ishigaki Island and were analyzed to interpret the geology of Ishigaki in USGS Professional Paper 399-A. Ruth Deike of the USGS Geologic Division began an inventory of the samples and thin sections in 2007, but the samples were soon after sent to the Core Research Center for storage. The inventory of the samples was completed by Chris Stuckey of the Core Research Center with a total of 807 hand samples and thin sections. Supplementary data has been added whenever possible from Helen Foster’s field notes and locality information derived from field map points as well as from USGS Professional Paper 399-A.
