What is Granite?

Granite-QuarryGranite is a widely occurring type of igneous stone.

Igneous means it is formed from magma, which is a hot, fluid rock beneath the surface of the earth. Granites are usually medium to coarsely crystalline. Granites can be pink to dark gray or even black, depending on their chemistry and mineralogy.

Granite has many potential origins within the earth’s crust, but to be granite it must intrude other rocks. This means that under pressure molten magma must be forced into other rocks. The actual process that produces granite in the earth’s crust is disputed and has led to varied schemes of classification.

Granite formations are nearly always massive (meaning they lack internal structures), hard and tough. As a result granite has gained widespread use as a construction stone.

The word granite comes from the Latin word “granum,” meaning a grain. This is because of its coarse-grained crystalline structure.

Historical Uses of Granite

The Red Pyramid of Egypt, the third largest Egyptian pyramid, is named for the light crimson hue of its exposed granite surfaces. The Great Pyramid of Giza contains a huge granite sarcophagus fashioned of “Red Aswan Granite.” Because of its durability and beauty, ancient Egyptians also used granite in high wear areas of buildings to make columns, door lintels, sills, jambs, and as wall and floor veneer.

Many large Hindu temples in southern India, particularly those built by the 11th century king Rajaraja Chola I, were made of granite. There is a large amount of granite in these structures and they are comparable to the Great Pyramid of Giza.

An unusual use of granite was for the construction of the rails for the Haytor Granite Tramway, in 1820 in Devon, England.

Modern Uses Of Granite

Granite has been extensively used as a dimension stone and as flooring tile in public and commercial buildings and monuments. With increasing amounts of acid rain, granite has begun to supplant marble as a monument material, since it is more durable. Polished granite is also a popular choice for kitchen countertops due to its high durability and aesthetic qualities.

Granite is currently known only to exist where it forms a major part of the continental crust. Granite often occurs as relatively small, less than 100 km sq. stock masses and in batholiths that are often associated with orogenic mountain ranges.

Granitic rock is widely distributed throughout the continental crust of the Earth and is the most abundant basement rock that underlies the relatively thin sedimentary veneer of the continents. However, since granite formations may exist as deeply as 150 miles, it is only accessible for quarrying in limited locations. The countries with the most commercial granite include Finland, Norway, Sweden, Spain, Brazil, India and several countries in southern Africa, such as Angola, Namibia, Zimbabwe and South Africa.