Granite is intrusive, which means that the magma was trapped deep in the crust, and probably took a very long time to cool down enough to crystallize into solid rock. This allows the minerals which form plenty of time to grow, and results in a coarse-textured rock in which individual mineral grains are easily visible.
Basalt is a common extrusive volcanic rock. An inert rock found worldwide, basalt is the generic term for solidified volcanic lava. Safe and abundant, basalt rock has long been known for its thermal properties, strength and durability.