Whats a pegmatite?
Picture granite as a mass of hot molten material (magma) below the surface of the earth, cooling slowly into solid rock. If part of the magma contains a lot of water, it will hold more dissolved minerals, and it will cool even more slowly than the surrounding granite. The effect of this very slow cooling of mineral-rich magma is the formation of pockets of large crystals (such as mica, quartz, tourmaline, and lepidolite) within the granitic rock, commonly found with all the crystals pointing inward. These bodies of rock within a granite mass with large crystals are called pegmatites. Most of the spectacular crystal-producing areas in the world, including Minas Gerais (Brazil), Sri Lanka and San Diego County, are pegmatite areas. Crystals up to 10 meters (33 feet) in length have been found in pegmatites. In San Diego County, pegmatite deposits have yielded famous and spectacular gemstone crystals, including many varieties of tourmaline, beryl, topaz, kunzite, and spodumene. Trace elemen
