1. A fine-grained igneous rock composed of feldspar and quartz, typically light-colored and formed from the rapid cooling of lava.
Usage: geology; technical

Examples

• The geologist identified the specimen as felsite based on its fine crystalline structure.
• Felsite forms when molten rock cools quickly at or near the Earth's surface.
• The volcanic outcrop contained bands of felsite alternating with darker basaltic layers.
• Under the microscope, felsite shows a characteristic microcrystalline texture.