Granite general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite. Granite is nearly always massive (i.e., lacking any internal structures), hard, and tough. These properties have made granite a widespread construction stone throughout human history. The average density of granite is between , its compressive strength usually lies above 200 MPa, and its viscosity near STP is 3–6·10 Pa·s. The melting temperature of dry granite at ambient pressure is ; it is strongly reduced in the presence of water, down to
A-type granite A-type granite A-type granites are a class of granite. They are characterised by low water and a lack of tectonic fabric. A stands for anorogenic or anhydrous. The granite class was proposed by Loiselle and Wones in 1979. It was in addition to I-, S- and M-type granites. The A-type granites form in an extensional tectonic setting. This could either be far from any orogeny, or after orogeny is completed. Chemical characteristics of A-type granites include high silica, alkalis, zirconium, niobium, gallium, yttrium and cerium. The ratio of gallium to aluminium is high, as is the ratio of iron to