| Granite is igneous rock. It is light in | | | | Where Granite is Found |
| color, but the grain can be medium or coarse. | | | | |
| The rock is composed mainly of alkali | | | | Granite is found on every continent of the |
| feldspar and quartz and is easily | | | | earth, especially in places where the earth |
| recognizable by the visible grains of the | | | | has been worn away by erosion. It often forms |
| various dark minerals. Granite rocks are the | | | | the core of mountains that forceful pressures |
| most common of all crystalline rocks found on | | | | within the earth have pushed upward. |
| the surface of the earth. They are found all | | | | Sometimes bodies of granite are found in |
| over the world, usually in great masses | | | | large outcroppings of rocks that are found in |
| called batholiths that often extend over | | | | chimney like and overhanging rock formations. |
| thousands of miles. This is a popular | | | | The Appalachian Mountain range in the United |
| material form use in monuments and buildings | | | | States is composed mostly of granite. It is |
| because of its hardness, durability and the | | | | also found in the Ozark Mountains, the Black |
| range of colors. | | | | Hills, and the front range of the Rocky |
| | | | Mountains. Granite is also produced in many |
| Composition of Granite | | | | states such as Georgia, California, Virginia, |
| | | | Minnesota, South Dakota and the Carolinas. |
| Granite is composed mainly of potash, | | | | |
| feldspar and quartz. The color of the rock | | | | How Granite is Formed |
| varies from gray to red and is usually | | | | |
| determined by the amount of the potash | | | | Geologists have two different theories about |
| feldspar. If there is a lot of glassy | | | | how granite was formed. One theory says that |
| crystals in granite, it will tend to have a | | | | granite formed directly from molten lava. The |
| bluish color. Dark minerals, such as | | | | other theory states that it was formed as a |
| hornblende, biotite mica and muscovite mica | | | | result of the alterations of other rocks and |
| can sometimes be found in granite. Some types | | | | that granite is metamorphic rock, rather than |
| of rock that are commonly called granite | | | | igneous rock. |
| contain different amounts of plagioclase | | | | |
| feldspar. Rocks that contain about one-fifth | | | | Uses of Granite |
| of the amount of potash feldspar relative to | | | | |
| the amount of plagioclase feldspar is really | | | | Granite has been used a building material for |
| granodiorite, rather than granite. Rocks that | | | | thousands of years. In ancient Egypt, the |
| have the same composition as granite, but | | | | obelisks were built from granite. Today, |
| have a very large amount of crystals are | | | | granite is used in building monuments, curbs |
| known as pegmatite. | | | | for roads, tombstones, and as a structural |
| | | | element in buildings. |