Description
Amazonite, sometimes also called Amazon stone, is a green variety of microcline feldspar. The name comes from the Amazon River, from which a certain type of green stone was formerly mined, but it is doubtful whether green feldspar also occurs in the Amazon region. Amazonite is only found in limited quantities. It was previously mined almost exclusively near the Russian town of Miass in the Ilmen Mountains of the Southern Urals, where it occurs in granitic rocks. More recently, crystals have also been found in Pikes Peak, Colorado, where it occurs in complexes with smoky quartz, orthoclase, and albite in rough granite or pegmatite. Several other locations in the United States, including Crystal Peak in the same Colorado, also contain amazonite deposits, and amazonite has also been found in pegmatite deposits in Madagascar. Because of the bright green color the mineral can acquire through polishing, amazonite is sometimes cut into pieces and used as a gemstone, although it can easily fracture. The origin of amazonite's green color has long been a matter of speculation. Many believed the color was caused by copper, as copper deposits often have blue and green hues. However, recent studies indicate that the blue-green color is the result of small amounts of lead and water in the feldspar (Hoffmeister and Rossman, 1985).
