The Lunar Mare Basalt suite

Recent studies have greatly expanded our knowledge of lunar mare basalts. Since 1976 there has been a revision of the Apollo 12 low‐Ti mare basalt suite and the discovery of a new very low‐Ti (VLT: < 1% TiO2) basalt suite at Apollo 17 and in the new Soviet samples from Mare Crisium (LUNA 24). Current studies suggest that the VLT basalts may be in some way related to the enigmatic “green glasses” which are found in the soils from every lunar landing site. Telescopic studies of spectral reflectance and crater systematics show that basalts of varying Ti content were extruded throughout the history of mare volcanism. These new discoveries indicate that mare basalts can no longer be classified into the two simple groups of older, high‐Ti basalts and younger, low‐Ti basalts.