Roci de la A la ZRocks from A to Z

Andesite is an intermediate volcanic rock that is typically formed in subduction zones where oceanic crust is being subducted beneath continental crust. The texture of andesite is typically porphyritic, meaning that it contains both fine-grained and coarse-grained crystals. The fine-grained matrix of the rock is composed of Plagioclase Feldspar and volcanic glass, while the larger crystals are typically composed of minerals such as Amphibole, Pyroxene, and occasionally Biotite or Quartz. Andesite texture varies depending on cooling rate and crystal size.