To set some ground rules: All of these are igneous rocks. Granite and rhyolite are considered felsic, while basalt and gabbro are mafic (click here for more information on mafic and felsic). What type of igneous rocks are basalt and rhyolite? Extrusive igneous rocks erupt onto the surface, where theyRead More →

Rhyolitic eruptions are most likely to be explosive. The material blown out of a volcano is called pyroclastic debris, or tephra. Bubbles that form quickly in a huge mass of sticky rhyolitic magma can shatter into a froth of innumerable tiny glass-walled bubbles, producing a rock called pumice. Why areRead More →