Granite and ryholite have similar composition but granite is course-grained whereas rhyolite is fine grained what is the difference?

Answer 1

Granite forms underground where magma cools slowly, allowing relatively large crystals to form. Rhyolite forms above ground as lava cools quickly, meaning that any crystals will be small.

Answer 2

The main difference is in the cooling rate - granite cools slowly beneath the Earth's surface, allowing larger crystals to form, giving it a coarse-grained texture. Rhyolite, on the other hand, cools rapidly at the surface, leading to smaller crystals and a fine-grained texture.