Illustrated Volcano Glossary
diorite
- VolcanologyDiorite is an intrusive igneous rock of intermediate silica content (53-63%). It is the equivalent of its extrusive (volcanic) counterpart andesite.Diorite is composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and/or pyroxene. The chemical composition of diorite is intermediate between gabbro and granite.