Albite is a common feldspar mineral, often associated with the plagioclase series. It contains no less than 90% sodium and no more than 10%of either potassium or calcium in the cation position in the crystal structure. Albite is the last of feldspars to crystallize from molten rock. It is often found with rare and beautiful minerals. Twinned crystals are common and single crystals showing a perfect twin are rarely found. It occurs in granitic and pegmatite masses, in some hydrothermal vein deposits. Albite crystal specimens are available at varying prices, depending on their weight and their mix with other varieties such as lepidolite and clevelandite.