What is Granite?
Structure and formation
Granite is an igneous rock made up of two main elements: feldspar and quartz, typically punctuated with other darker minerals, such as mica, muscovite or amphibole hornblende. Igneous rocks are those that are formed through the cooling of magma. Magma is the hot molten rock found in the Earth’s mantle. As the Earth’s tectonic plates shift, friction and heat generate a build-up of pressure, causing magma to be pushed upwards towards the planet’s surface. The molten liquid forces its way upwards through gaps and crevices within the Earth’s crust. As it rises, it gradually cools, forming massive solid deposits known as plutons and batholiths. Granite is the most common igneous rock found in the Earth’s continental crust. The large mineral crystals in granite show that it was formed by magma that has cooled slowly over a long period of time.
The mixture of minerals that comprise granite means the coloring of the stone varies between red, white, pink and grey. The word granite comes from the Latin granum meaning grain, as the grain of the rock is easily visible to the naked eye. One of the most easily recognisable rocks, granite has a distinctive salt-and-pepper speckled effect, due to the darker elements being mixed throughout the lighter quartz and feldspar. Granite is very hard and durable; a special diamond blade is required to cut it into slabs. As it forms deep underground in large plutons, it is a massive stone and extracting it from beneath the sedimentary rock that forms the Earth’s surface is a complex process, requiring explosives. The rock is usually removed from the ground in blocks measuring 10ft in length by 5ft in width and depth. These blocks are removed to factories, where they are cut into slabs and e
ither polished to give a glossy finish or heated to give a rough blistered finish, such as that regularly used in non-slip flooring.
Granite is a material used in a diverse range of building products, due to its strength and durability. It is a popular choice for worktops, as it is resistant to heat and does not harbour bacteria such as salmonella. Further to this, the surface generally remains cool (making it good for baking) and can be polished to give a very attractive high gloss finish. Another typical use of granite inside the home is for bathroom and kitchen tiles. The speckled effect gives a lovely finish, while the hardness and durability of the material ensures water is kept from getting into the walls or floors and that the tiles are less likely to get chipped or cracked than those made of porcelain or ceramic. Outside the home, the timeless, elegant appearance of granite has seen it become a common choice for gravestones, monuments and sculptures in recent years. The added advantage of using granite to build such structures is that the hardness of the stone means it is resistant to abrasion, erosion and acid rain.