Andesite is a type of igneous rock that is found in most volcanic regions of the world, especially around volcanoes that line the Pacific Basin. Its main mineral components are plagioclase, pyroxene, and hornblende. The study of andesite has helped scientists understand the geological processes by which this igneous rock can be formed.
Andesite is generally found as surface deposits and may therefore be considered the "extrusive" equivalent to diorite.These rocks are characteristic of subduction tectonic environments in active oceanic margins, such as the west coast of South America. This type of rock is plentiful around volcanoes that line the Pacific Basin.
