Granite is a natural stone and has been used as a building material for many centuries. Granite is an igneous rock, which means that it is formed by volcanic activity, which strength approaches that of diamonds. Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles and other minerals. Granite is very durable and can only be scratched by something harder than granite. Granite can withstand heat up to 1200 degrees F.