Granite

Mount Rushmore

Granite is the best known igneous rock, formed by magma slowly crystallizing underneath Earth’s surface, and characterized by grains large enough to be visible to the naked eye. The main minerals Granite is composed by are quartz and feldspar, but it also includes minor amounts of micas, orthoclase and amphiboles. Its colours vary depending on the quantities of these minerals, generally being a light coloured stone, ranging from pink to red to white, with smaller black grains.

Specifically, Granite is a plutonic rock whose quantity of quartz is between 10 and 50 percent of the felsic components, and alkali feldspar accounts for 65 to 90 percent of the total feldspar content. This is although a very technical definition which would require geological studies by petrologist (people who study rocks) before confirming whether a stone is Granite or not; in fact, many rocks identified as Granite will not be called so by petrologists, they might instead be defined alkali granites, granodiorites, pegmatites, or aplites, or simply be called “granitoid rocks” to make it easier.

In the commercial business, any stone with visible grains which is harder than Marble is called a Granite; for this reason materials like Gabbro, Schist, Basalt or Quartzite (even though people started categorizing this last one separately) are commonly sold as Granite.
The most famous Granite formation, then converted into a piece of art, everyone has seen at least once is Mount Rushmore, South Dakota, carved from a Granite mountain.

This stone is widely used indoors, mainly for kitchen worktops or flooring, and outdoors, for landscaping and wall cladding. In the Mohs hardness scale, being composed mainly by quartz and feldspar, it scores between 6 and 7, which is a considerably higher number than Marble, which scores between 2 and 3. Because of its high resistance to abrasion and low water absorption characteristics, the finishes appliable to this stone are countless, the most popular being Polished, Honed and Leather.

Here is a list of the most common stones traded as Granite:

(click on names to open material sheet)