Rhyolite lavas occupy the opposite end of the chemical composition spectrum from basalt, and rhyolite flows are thick and pasty when they erupt often developing complexly folded layers as they ooze across the landscape.  They also develop beautiful colors ranging from red to yellow to purple.  Some rhyolite volcanoes explode, sending huge clouds of ash, pumice and broken rock into the air, which can weld together into a hard tuff when it falls back to earth.  Welded tuffs have a similar range of colors and interesting textures that develop from the mixture of materials and the flattening that accompanies welding.