In the third of our series of blogs about the origins of natural stone, we are looking at where granite comes from. Granite is one of the most durable natural stone tiles that comes in many colours and shades and can be used both for interior and exterior projects. You can see the variety we offer at our showroom and here.
Granite is a wide-spread type of intrusive igneous rock that has granular texture formed by the large and visible crystals of quartz, alkali feldspar and mica. It is formed beneath the earth's surface at depths up to 50 km by the slow cooling of magma. According to the scientific definition for a stone to be classified as granite it shall contain between 20 and 50% quartz particles and no more than 65% alkali feldspar. Depending on the predominance of the different minerals found in it, granite is mainly white, pink or gray but other colours are also seen in nature. The stone got its name from the Latin word granum, which means grain. Gneiss, basalt, gabbro and sodalite are other stones that are similar to granite both in looks and composition.
Depending on where it is quarried, granite may differ in its physical properties such as hardness, density, porosity and outer appearance, hence comes the difference in its market price. The stone has many applications in the carving of monuments, construction of buildings, decoration of commercial and residential premises. Low quality granite is often crushed into smaller pieces to be used as paving.
Granite together with other igneous rocks forms 95% of the Earth's crust and can be found almost all around the world, including in seabeds. It is most often found around mountain ranges and forms rounded hills along the mountain range. If we put aside the bureaucratic and financial hindrances that might surround its extraction rights, the actual process of quarrying granite is pretty simple. Once the granite deposit is located the first step is to remove vegetation, soil and other rocks that cover it and thus the face of the granite stone is exposed. It is then removed from the site in benches using a technology that is appropriate for the given quarry. Granite can be removed by drilling holes around the bench that is to be quarried, which is then cut by means of diamond wire saws, using hydraulic splitters or small explosives. Afterwards the bench is transported to a storage place using heavy machines where it is further cut into slabs or processed in any other way as per the requirements of the client.
Granite was a very popular building stone in ancient times – it was used in the construction of the Red Pyramid of Egypt, alongside limestone, and the Great Pyramid of Giza contains a granite sarcophagus. There were several quarries in Egypt to extract granite and some of them are still preserved. One of them is the famous Aswan quarry, where you can still see an unfinished huge obelisk lying in it.
Aswan granite quarry - source of obelisks
One of the biggest granite quarrying companies is the Rock of Ages corporation, which was founded in 1885. Their quarry in Graniteville, Vermont is a famous tourist attraction, beside being absolutely functional.
Rock of Ages quarry
The world's largest granite quarries were in Barre, Vermont. They were even depicted on a postcard, which is part of the Boston Public Library Tichnor Brothers collection under the No 87375. The picture for the card is believed to be taken somewhere between 1930 and 1945.