Trachyte

noun

1. A light-colored igneous rock consisting essentially of alkali feldspar.
2. A volcanic rock exhibiting a characteristic roughness when handled.
3. An igneous rock, usually light gray in color and breaking with a rough surface. It consists chiefly of orthoclase feldspar with sometimes hornblende and mica.
4. A pale igneous rock consisting mostly of potassium feldspar and plagioclase.