Amazonite

Amazonite, also known as Amazonstone, is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. Its chemical formula is (KAlSi3O8), which is polymorphic to orthoclase.Deep robins-egg blue color amazonite crystal on smoky quartz and albite, from Teller County, Colorado (size: 3.4 x 3.3 x 2.5 cm).Amazonite crystal on smoky quartz, from Pikes Peak, El Paso County, ColoradoLarge deep-turquoise amazonite crystal with attached stark-white microcline, from Konso, SNNPR, Ethiopia (size: 16.4 x 11.9 x 8.0 cm).Two smoky quartz crystals surrounded by amazonite crystals, from Smoky Hawk Mine, Crystal Peak, Teller County, Colorado (11.0 x 8.2 x 6.3 cm).Amazonite crystals on orthoclase, from Konso, SNNPR, Ethiopia.Deep lustrous crystal of amazonite, from Take 5 Claim, Crystal Peak, Teller County, Colorado (size: 4.4 x 4 x 3.5 cm). Amazonite, also known as Amazonstone, is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. Its chemical formula is (KAlSi3O8), which is polymorphic to orthoclase. Its name is taken from that of the Amazon River, from which certain green stones were formerly obtained, but it is doubtful whether green feldspar occurs in the Amazon area. Although it has been used for over two thousand years, as attested by archaeological finds in Egypt and Mesopotamia, no ancient or medieval authority mentions it. It was first described as a distinct mineral only in the 18th century. Green and greenish-blue varieties of potassium feldspars which are predominantly triclinic are designatedas amazonite. It has been described as a 'beautiful crystallized variety of a bright verdigris-green' and as possessing a 'lively green colour.' It is occasionally cut and used as a gemstone. Amazonite is a mineral of limited occurrence. Formerly it was obtained almost exclusively from the area of Miass in the Ilmensky Mountains, 50 miles southwest of Chelyabinsk, Russia, where it occurs in granitic rocks.