Glossary: Andesite
A dark-colored, fine-grained volcanic rock that is intermediate in composition (with respect to silica, magnesium and iron) between rhyolite (high silica, low magnesium and iron) and basalt (low silica, high magnesium and iron).
A dark-colored, fine-grained volcanic rock that is intermediate in composition (with respect to silica, magnesium and iron) between rhyolite (high silica, low magnesium and iron) and basalt (low silica, high magnesium and iron).