Igneous rocks form when molten magma
pushes up into the crust
or through it. Igneous rock contains various minerals
in seemingly randomly arranged, interlocking
crystals. There are two types of igneous rock - intrusive
Intrusive rocks cool slowly with big crystals. They cool slowly because they're underground. An example of an intrusive rock is granite. Granite is very hard.
Extrusive rocks cool quickly with small crystals. An example of an extrusive igneous rock is basalt.