What is Granite?

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 grayish 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 usually 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 rock lying on top of it have been worn away by wind, water, or ice. It may also have been trust 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 granite outcrops.


When granite is exposed to the air, weathering begins at once. The feldspar 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 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 the pyramids.

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