What type of rock forms when tiny crystals in magma form?

When tiny crystals form in magma, they create an igneous rock known as "intrusive" or "plutonic" rock. This occurs when magma cools slowly beneath the Earth's surface, allowing the crystals to grow larger, such as in granite. If the magma cools quickly on the surface, it forms "extrusive" or "volcanic" rock, like basalt, where the crystals are much smaller.