Granite and rhyolite are two of the most commonly found igneous rocks that possess a high silica content. They are formed through the cooling of magma above or below the Earth's surface.
Granite is found below the Earth's surface and is composed primarily of lightly-colored quartz and feldspar minerals. It has a coarse grain type with typically large crystals. Rhyolite is considered an extrusive counterpart to granite, as it contains a high amount of feldspar and quartz and has a similar appearance. It forms above ground from highly viscous lava and displays a fine grain type. Rhyolite typically has extremely small crystals due to a fast cooling process that prevents the crystals from growing.