Figure F12. Digital photomicrograph (crossed nicols) of a coarse-grained volcaniclastic sandstone. A subrounded lithoclast of basalt with microphenocrysts of feldspar and clinopyroxene is present in the center. In addition, surrounding acidic clasts (dark, speckly) are present. Other grains are pyroxene, biotite, quartz, feldspar, and bioclastic grains set with a calcite spar cement (interval 180-1114A-15R-1, 46-48 cm).