Pictures and Descriptions of Igneous Rock Types ThoughtCo
Andesite is an extrusive igneous rock that is higher in silica than basalt and lower than rhyolite or felsite. Click the photo to see the fullsize version. In general, color is a good clue to the silica content of extrusive igneous rocks, with basalt being dark and felsite being light. Although geologists would do a chemical analysis before ...