What intrusive crystal size?

Intrusive crystal size refers to the size of crystals that form within igneous rocks as they cool slowly underground. These crystals are generally larger than those found in extrusive rocks, as the slower cooling process allows more time for crystal growth. Common examples of intrusive rocks with large crystal sizes include granite and diorite. The size can vary from a few millimeters to several centimeters, depending on the cooling rate and the composition of the magma.