Granite Tutorial

Composition

• Granite belongs to the geological class of igneous rocks. These types of rocks were formed by the slow cooling of magma during a process that could take thousands of years. This slow cooling process allowed for the growth of crystalline materials, primarily quartz, within the granite. These crystals are responsible for giving granite its unique, decorative appearance. The type of crystals that form in the granite may result in a wide variety of colors and patterns in the rock. Feldspar and mica are other minerals that are commonly found in granite.

Properties

• Granite is one of the hardest of all naturally occurring materials, with a hardness rating of around 7 on the Mohs Scale, compared to diamond, which has a rating of 10. Although granite is quite tough, it can be chipped or broken if struck with a hard object. Granite is quite dense, so it resists staining. It can be polished to a high gloss, making it attractive for decorative applications. It is heat resistant at temperatures common to household uses, but may be affected by intense heat.

Applications

• Granite is tough and resistant to wear, making it appropriate for use as floor tile in residential, commercial and municipal settings. Granite can be cut, hewn or sawed into thin slabs. It can be chiseled and shaped without producing secondary flaws, making it appropriate for monuments and memorial stones. Its heat resistance and durability have made granite a popular material for kitchen countertops. Since granite is water resistant it can be used to line shower and bath stalls.

Radon

• All naturally occurring rocks, including granite, have the potential of containing radioactive materials such as radium or uranium, according to the U.S. Environmental Protection Agency. When these radioactive elements decay they produce a colorless, odorless, radioactive gas called radon. The EPA notes that granite is less likely than some other common building materials to emit radon, due to granite's nonporous nature. If you are concerned about the possibility of radon in your home due to the presence of granite tiles or countertops, the EPA recommends testing the air in your home with a do-it-yourself test kit.