How Granite Countertops Are Made
Many people enjoy granite countertops because of the stone's great natural qualities. Let's take a look at how these counters are made, from the quarry to your kitchen.
Italy was a leader in granite processing before the mid 1990s and 2000s. In the early 2000s, more countries became a bigger part of the industry, both quarrying and processing granite. The United States is one of these countries, but others generally can provide more granite at lower prices. Thus, much of the granite in the United States is imported from Brazil, India, and China. About half of the imported granite in the US comes from Brazil.
Even though the United States imports a lot of granite, it is home to some of the largest granite quarries in the world, located in Vermont. The Rock of Ages corporation is one of the largest granite companies in the world, founded in 1885, and located in Graniteville, Vermont. This functioning quarry is also a popular tourist destination.
How is granite mined?
Your granite countertops begin in a quarry. Mining natural stone like granite begins with cutting a large block out of the quarry. It's important that the block is completely solid, without any cracks running through it. Imperfections mean that the block will not be able to be used to create uniform slabs to be used for various purposes.
The blocks are cut with a wire saw, which is a cable that has diamond beads regularly spaced along its length. This cable is threaded through holes drilled in the stone, and then spliced together into a loop. An engine provides the energy to drag the wire through the stone, maintaining consistent tension.
The blocks created with this wire saw are very large: about 30 to 50 feet in length and width, and about 6 to 9 feet in depth. This large chunk of stone is pushed out of the cliff face once it's cut, using different tools such as wedges, excavators, airbags, or even explosives. If all goes well, the block lands on a soft bed of dirt in one piece.
Next, the block is cut into slabs. This is done with gang saws, which have many equally spaced parallel blades or diamond wires, creating multiple slabs with one cut. This may take up to 50 hours with blades (diamond wire saws are faster). These slabs are generally around 9 by 6 feet (3 by 2 meters) in size, and either 3/4 or 1 1/4 inches thick.
These slabs are usually then polished on one side, and they're bundled togther in batches from the same block so that buyers can purchase multiple slabs that have similar coloring.
These slabs are fabricated into countertops based on specifications provided by an architect or designer. Fabricators have samples available, but as a natural material, there's always variation, even between slabs that were cut from the same block, so it is often possible to choose a specific slab from a warehouse. The specific measurements are provided and a computer program is used to lay out the cuts on the slab. Once the counters are cut to specifications, they're ready to be installed.