Study of the mineralogy of the Chester sandstones of southwestern Indiana shows an abundance of a very few minerals, and a trace of many more. The heavy minerals consist of 50 to 100 percent leucoxene, 25 to 50 percent zircon, and 10 to 25 percent tourmaline. Rutile, ilmenite and brookite compose from 1 to 10 percent of the heavy minerals. Magnetite, anatase, garnet, hornblende, kyanite, muscovite, hypersthene, pyrite, chlorite and barite are present sporadically and always in small quantity. The light minerals consist of quartz, feldspar, and calcite. The outstanding feature of the mineralogy of the Chester sandstones is the occurence and nature of the mineral leucoxene together with the other closely associated titanium-bearing minerals, brookite and rutile. It is recognized that the titanium oxide minerals, brookite and rutile, are developed authigenically from the decomposition of leucoxene.