The Probert Encyclopaedia of Rocks & Minerals

ANDESITE

Andesite is a crystalline igneous rock, occurring mostly in lava flows, but sometimes in dykes and veins. It consists principally of plagioclase feldspar, and is often porphyritic, showing large crystals of feldspar scattered through a fine-grained mass, usually of small feldspar crystals, but often containing much glassy material. Andesite forms most of the recent volcanic rock of the Andes, and is thus named after the Andes.
Research Andesite