Figure 19. Photomicrograph showing a wide range of lithic and vitric clast types present in a lithic vitric tuff from Subunit IID (Sample 192-1184A-31R-7, 40-43 cm). The clasts include glass shards (light brown), basalt, and tachylite (black). The glass is completely altered to smectite, and the matrix is composed mainly of zeolite (field of view = 5.5 mm wide; plane-polarized light).