is rhyolite extrusive
Rhyolite is an extrusive igneous rock with a very high silica content. It is usually pink or gray in color with grains so small that they are difficult to observe without a hand lens.Rhyolite is made up of quartz, plagioclase and sanidine, with minor amounts of hornblende and biotite.Trapped gases often produce vugs in the rock. These often contain crystals, opal or glassy material.hyolite is a rock that is rarely used in construction or manufacturing. It is often vuggy or highly fractured. Its composition is variable. When better materials are not locally available rhyolite is sometimes used to produce crushed stone.