1. A fine-grained volcanic rock of intermediate composition, typically gray or dark in color, composed mainly of plagioclase feldspar and one or more mafic minerals.
Usage: geology; technical

Examples

• Andesite is commonly found in volcanic arcs around the Pacific Ring of Fire.
• The mountain's slopes were composed largely of andesite lava flows.
• Geologists identified andesite samples from the volcanic eruption.
• Andesite forms when magma of intermediate silica content cools relatively quickly.
• The dark andesite rocks contrasted sharply with the lighter granite formations nearby.