Granite: From Formation to Product

Granite, which is probably the world’s best known igneous rock, is widely used in a large number of industries. Here is a brief timeline of its production, from formation to conversion into the everyday products that we use.

Formation

Granite is formed when magma, a mix of molten and semi-molten rock, slowly crystallizes beneath the earth’s surface. Granite consists of a variety of substances, including quartz, feldspar, mica and other minerals. It is usually colored red, pink, grey or white although grains of minerals can be clearly seen through a piece of rock. The way granite is formed can affect the look and strength of the stone, hence the different colors of granite kitchen worktops available.

Mining

There are various methods of extracting pieces of granite from the ground. Granite tends to exist in large slabs in granite quarries, so blasting is not used, as it would shatter the slabs. Instead, granite has to be cut from the earth in large pieces using specialised large-scale industrial cutting equipment. The most common means of cutting granite from the earth are drilling and jet piercing. Heavy duty cranes and chemicals are also used in the process of digging around the granite slabs to release them and lift them onto large trucks to transport them to the processing site.

It takes around 30 days to turn granite from a rock in the Earth to a counter ready to make your kitchen look amazing. That’s around 2 days to slice a block into individual slabs, 2 days to apply the resin and the rest of the time getting the slabs to market.

Granite is mined in the USA but can also be imported from many places around the world. You can import African and Indian Granite as well as from South America.

Processing

Processing, or fabrication, of the granite takes place either on the extraction site or at a dedicated processing plant. The process involves three main functions; sawing, polishing and routing.

Sawing

The blocks of granite that have been mined are cut into smaller slabs using specialist cutting machinery. One of the most efficient and popular granite saws is the diamond wire saw. When the block of granite has been reduced to a workable size, it is cut again, using a bridge saw, into the shape of the product that it is intended to be used for. One again, diamonds are involved in the cutting process. Another modern type of saw is one that uses jets of water combined with an abrasive material that cuts the granite quickly and smoothly.

Polishing

The process of polishing produces the type of finish that is required for the completed product. The type of finish can vary from rough and abrasive, as in the granite used in paving stones, to the mirror finish of the type seen on many kitchen worktops. The polishers that are used are made up of abrasive, rotating pads. The finer the abrasive surface is, the higher the polish will be.

Routing

Routing involves the creation of edge profiles and the cutting of designs for larger item such as fireplaces. The designs may be simple or complex and the process involves the use of a spinning, diamond covered, water-cooled blade.

Completing the Process

Whilst some granite products, such as paving stones, are ready for immediate use following processing, there is a final stage that certain products have to go through. It is not possible, for instance, to cut a slab of granite for individual kitchen worktops without seeing the worktop itself. This final cutting process is usually carried out by granite merchants based on templates that are prepared to show the dimensions and characteristics of the surface required.

granite formation infographic

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