Did you know that the continents of the world rest on granite? It is the hard rock that forms much of the earth’s outer crust. The name “granite” comes from the Latin word granum, meaning “grain”. The grains in granite are crystals of quartz, feldspar, mica, and hornblende.
Granite varies in color. It may be greyish or pinkish, and it may also be colored by impurities. Granite is one of the “igneous” or fire-made rocks. It is formed, for the most part, at some depth in the earth. Granite was formed when hot rock or molten “magma” was slowly cooled in the earth. Magma is a dough-like rock.
Granite is us ly formed under mountain folds where the rocks on the surface act like a blanket to prevent its rapid cooling. The only time it is found at the surface is when the rocks lying on top of it have been worn away by the wind, water, or ice. It may also have been thrust upward by movements of the earth. When the surface rocks have weathered away, the great masses of harder granite are left. In the United Kingdom, Dartmoor, the rugged Cornish Coast, the Lake District. the Antrim Hills and the Isle of Skye are all granite outcrops.
When granite is exposed to the air, weathering begins at once. The feldspars break down first, changing to clay and salts. Only the quartz remains unchanged. In time, giant granite mountains are reduced to minerals. These minerals, with the remains of plants and animals, added, form the soil. Granite is one of the strongest building stones. It is used for building exteriors, monuments, and gravestones. It must be highly polished to prevent weathering. The ancient Egyptians used granite to build temples, columns, and pyramids.
What Is Granite Made Of?
Granite is a light-colored plutonic rock found throughout the continental crust, most commonly in mountainous areas. It consists of coarse grains of quartz (10-50%), potassium feldspar, and sodium feldspar.