hand sample of vesicular rhyolite

ancient are ash background bedrock clues college collegiate creamy crystalline crystals curriculum diamonds eruption escaped explosive extrusive felsic fine formation frothy gases geologic geology geoscience grained hand hardness high holes holey igneous intergrown labeled lava magma molten object one outgassing permeate rhyolite rock sample samples school small solid solitary state stone term that things tourist vesicles vesicular volcanic volcano vug welded where white