The garnets analyzed in this study are from Sample 183-1137A-33R-3, 50-53 cm (Shipboard Scientific Party, 2000). They occur as sedimentary grains within the sandstone of Unit 5, beneath Unit 4 subaerial flood basalts, and above Unit 6 conglomerate. Both the Unit 5 and Unit 6 sediments are interpreted as braided stream facies deposited during a hiatus between flood basalt eruptions.
Unit 5 comprises medium-grained sandstone to siltstone. Garnet sand grains are somewhat smaller (0.15-0.2 mm) than the dominant lithic and feldspar grains. They are angular, consistent with their hardness (6.5-7.5) and occurrence in immature sediment. Some of the grains have a purplish shade in plane-polarized light.