The huge, grand granite that surrounds us |15 April 2013

Seychelles granites contribute a lot towards the islands’ natural beauty

They come in every form. They are the backbones of our mountains and they hang sometimes precariously against them with shiny deep brownish colour. They more or less do not support any vegetation attached to them. They form part of the natural beauty of the Seychelles environment.

Even if we see them everyday do we know much about the granite rocks? We take you on a short voyage of discovery.

 Granite is a strong stone because its mineral grains have grown tightly together during a very slow cooling period. The quartz and feldspar that compose it are harder than steel. This makes granite desirable for buildings and for ornamental purposes such as gravestones. Granite can resist weathering and acid rain. Here in Seychelles we use granite is used as construction material – be it crushed for macadam, crusher dust or polished into large tiles used for kitchen tops or tombstone. Chunks of granite are also used to build walls. It is believed here in Seychelles that walls built of granite are the strongest and the best. The ancient Egyptians used granite to build temples, columns, and the pyramids.

 It is the hard rock that forms much of the earth's outer crust. The name "granite" comes from the Latin word gramim, meaning" grain". The grains in granite are crystals of quartz, feldspar, mica, and hornblende. Granite varies in colour. It may be greyish or pinkish and it may also be coloured 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 rocks lying on top of it have been worn away by 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 remains of plants and animals added, form the soil.