A granite counter top is made of a rock called granite. Granite is a common type of igneous rock. Granite rocks are usually white or buff in color and have medium to coarse grain, sometimes with some individual crystals larger than the groundmass forming a porphyry. A porphyry is a rock. Granite rocks can be pink, dark grey or even black. The color of a granite couter top depends on the granite rock’s chemistry and mineralogy.
Protuberancies of granite tend to form rounded mountain ranges. They also form large hills called tors and terrains of rounded boulders jutting out of flat and sandy soil. Granite will also sometimes occur in a circular depression that is surrounded by a range of hills. These formations are formed by a series of contact metamorphic rocks that have been baked by the heat of intrusive granitic masses. In geology an intrusion is usually a body of an igneous rock that has crystallized from a molten magma below the surface of the Earth.
Bodies of magma that solidify underground before they reach the surface of the earth are called plutons, named for Pluto, the Roman god of the underworld. Correspondingly, rocks of this kind are also referred to as igneous plutonic rocks. Granite is not a substance that can be whipped up in a modern day laboratory. There are a lot of enviromental factors that make the granite used in granite counter tops.
Granite is nearly always big, hard and tough. Because granite is so tough, it has gained widespread use as a contstruction stone. Granite counter tops are dense. They have an average denisity of 2.75 g/cm3; with a range of 1.74 to 2.80. The etymology of the word granite is Latin. Granite primarily consists of orthoclase and plagioclase feldspars. It also contains quartz, hornblende and biotite. Muscovite and minor accessory minerals such as magnetite, garnet, zircon and apatite are also present in granite. Rarely, a pyroxene is present. Granite has a beautiful coarse grain from the presence of all of these minerals that make is very lovely for a granite counter top. Granite is classified as a coarse grained plutonic rock.
Geologists use a QAPF diagram to classify granite. A QAPF diagram is a double triangle diagram which is used to classify igneous rocks based on their mineralogic composition. The acronym, QAPF, stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for classification in QAPF diagram. Granite is classified according to the QAPF diagram for coarse grained plutonic rocks (granitoids) and is named according to the percentage of Quartz, Alkali feldspar (orthoclase) and Plagioclase Feldspar on the A-Q-P half of the diagram. Highly peralkaline forms of granite which are silica undersaturated may have a feldspathoid such as nepheline, and are classified on the A-F-P half of the diagram.
