Figure F10. Volcanic rock fragments: felsitic grains are characterized by microcrystalline quartz and feldspar crystals of equant dimensions. The presence of abundant feldspar is denoted by the prominent yellow stain. These grains also contain a substantial admixture of clay-size clay minerals and various opaque crystals. Left = plane-polarized light, right = cross-polarized light.
Previous | Close | Next | Top of page