
Microcline feldspar variety Amazonite with Smoky
Quartz from Two Point Claim, Teller County,
Colorado
'Amazonite' (sometimes called "Amazon stone") is a green variety of
microcline feldspar.
The 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.
Amazonite is a mineral of limited occurrence. Formerly it was obtained almost exclusively from the area of
Miyask in the
Ilmen mountains, 50 miles southwest of
Chehabinsk,
Russia, where it occurs in granitic rocks. More recently, high-quality crystals have been obtained from
Pike's Peak,
Colorado, where it is found associated with smoky
quartz,
orthoclase, and
albite in a coarse
granite or
pegmatite. Crystal Peak, Teller County,
Colorado is a well-known locality for crystals of amazonite. Some other localities in the
United States yield amazonite, and it is also found in
pegmatite in
Madagascar.
Because of its bright
green colour when polished, amazonite is sometimes cut and used as a
gemstone, although it is easily fractured.
For many years, the source of amazonite's color was a mystery. Naturally, many people assumed the color was due to copper because
copper compounds often have blue and green colors. More recent studies suggest that the blue-green color results from small quantities of
lead and water in the feldspar. (Hoffmeister and Rossman, 1985)
See also:
List of minerals
References
★
, Hoffmeister and Rossman, , , Am. Min., 1985
★
Colorado Gem Trails: And Mineral Guide, , Richard, Perl, Swallow Press, 1972,
★ http://www.mindat.org/show.php?id=184
★ http://webmineral.com/data/Microcline.shtml