Geology And Geophysics

How Granite is Formed

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"How Granite is Formed"
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Highly durable and extremely beautiful granite is most prized of all rocks. Traditionally widely used as a building material, especially in ancient Egypt, today granite is more likely to be found as a countertop in a kitchen.

Granite is an igneous rock and as such is formed when molten rock, magma, cools slowly. Magma is found between the mantle and the crust of the earth, and often flows towards the surface of the earth. As the magma rises to the surface though it starts to cool down, and unless it finds an escape route, could solidify as an intrusive rock formation. The solidification though is a slow process, and where plutons are formed, plutons being large chambers of magma, it can take millions of years for it to actually solidify.

The slowness of the cooling process, and also the pressure involved, ensures that large crystals form, and therefore granite is formed. To form granite though the magma itself must have a particular type of composition, and must in particular be high in silicate concentration, with quartz, feldspar and mica all present.

The slowness of the process that creates granite ensures that it is one of the hardest of all rocks, and both feldspar and quartz can be harder than manufactured steel.

The formation of granite means that granite can be found in a range of colours, from pink through to grey and black. The colour itself is dependent upon the mineralogy of the granite, and in particular the chemistry composition of the feldspar. Feldspar is natural light in colour, and a higher concentration of it will result in pink granite.

Today granite is quarried, where huge blocks are cut away and then cut into thinner slabs. It is these slabs that are used by kitchen makers.

Granite though can be seen all around the world in its natural environment. The hardness of granite means that it outlasts many of the metamorphic rocks that surround it as it forms. As the landscape changes, the earth’s surface can erode leaving granite outcrops, tors or rounded massifs. This creates distinct landscapes the likes of Dartmoor and Exmoor in England.

Granite has a natural beauty that ensures that when found in the natural environment it can be an awe inspiring site. This beauty though can be transported into the home, with granite work surfaces high in demand. When in the kitchen though it is easy to overlook the millions of years, and the process involved, that it takes to actually form granite.

More about this author: Tim Harry

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