Types of Stone
Granite is a light-colored igneous rock with grains large enough to be visible with the unaided eye. It forms from the slow crystallization of magma below Earth's surface. Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals. This mineral composition usually gives granite a red, pink, gray, or white color with dark mineral grains visible throughout the rock. Granite is best applied as counter tops, floor tiles, paving stone, curbing, stair treads, building veneer, and cemetery monuments. Granite is hard enough to resist most abrasion, strong enough to bear significant weight, inert enough to resist weathering, and it accepts a brilliant polish. These characteristics make it a very desirable and useful dimension stone.
Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite and usually contains other minerals, such as micas, quartz, pyrite, iron oxides. When acidic elements come in contact with calcium carbonate, it creates an etch. An etch is not a scratch. Rather, it is merely the removal of polished finish on the surface. Marble can come in a polished or honed finish. It is softer than granite, so the best application for it is on fireplace surrounds, bathroom, some furniture, and in generally less-traveled areas. Marble is rated as a three on the Mohs Hardness Scale.
Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together. The result is a network of interlocking quartz grains of incredible strength. Quartzite, with a Mohs hardness of seven along with greater toughness, is superior to both granite and marble in many uses. It stands up better to abrasion in stair treads, floor tiles, and countertops. It is more resistant to most chemicals and environmental conditions. It is available in a range of neutral colors that many people prefer.