Some examples of intrusive igneous rocks are granite, diorite, syenite, gabbro and pyroxenite. These rocks were formed over eons in magma chambers deep in the earth under high pressure and high temperatures.
Granite is a rock that's often used as a building material, because it is both strong and aesthetically pleasing. Granite is a felsic rock, which means it's made largely out of feldspar and quartz. It can also contain other "impurities" such as pyrite, zircon and garnet.
Diorite resembles granite, though it's made largely out of a mineral called plagioclase. It also contains smaller amounts of hornblende and other minerals. Diorite is much less common than granite.
Named after a city in Egypt, syenite is a rock with a medium grain that's made from plagioclase, potassic feldspar and amphibole. It is also used as a building stone.
Gabbro is a dark and coarse-grained rock that's considered mafic instead of felsic. This means it is made of minerals made largely of iron and magnesium, such as olivine. It is used as a facing stone for buildings and can be dark gray, brown or green.
Pyroxenite is an ultramafic rock with a coarse grain. Its colors can range from green to brown to black.