Andesite is a type of volcanic rock that is commonly found in areas with volcanic activity. It is primarily composed of minerals like plagioclase, amphibole, and biotite, giving it a medium gray color. Andesite typically forms from the cooling and solidification of lava that has a moderate silica content, making it less viscous than rhyolite but more viscous than basalt. This rock is often associated with volcanic arcs, which are formed at convergent plate boundaries. Andesite can be found in regions such as the Andes Mountains in South America, where it plays a significant role in the geological landscape. Its unique properties make it important for understanding volcanic processes and the Earth's crust.