From Rings 'n Things gemstone index.
A great reference.

"Amazonite

aka Amazon Stone

Amazonite is a rare blue-green variety of microcline (a feldspar mineral) used as a semiprecious stone. Its brilliant color was once thought to be caused by copper, but now is attributed to the presence of lead or possibly iron. Amazonite is an opaque stone, often found with white, yellow or gray inclusions and a silky luster or silvery sheen. It takes a relatively good polish, but still maintains a somewhat raw, natural texture that makes it even more appealing to many people. Its name is derived from the Amazon River, although no deposits have been found there. Amazonite should be cleaned in lukewarm soapy water, never with a steamer or ultrasonic cleaner. Abrasives, acids and other chemicals can damage amazonite, as can scratches and sharp blows.
The ancient Egyptians and other Middle Eastern cultures made items from amazonite. It also has been found among artifacts of Pre-Columbian Central and South America. The most sought-after amazonite has historically come from Russia, where deposits are found in granite along the Ilmen Mountains. Europeans familiar with the Russian stone confused it with another green stone they saw in South America's Amazon Basin, which later turned out to be a form of nephrite jade. However, the name "Amazon stone," then "amazonite," had already become attached to the green feldspar. The Pike's Peak district of Colorado, U.S.A., became the most important source of amazonite after 1876. When examples of the stone were unveiled at the Centennial Exhibition, their impressive purity and size eventually put competing Russian mineral vendors out of business.
Amazonite is believed to have many healing characteristics, including improving your skin, marriage, clarity of thought and social interaction. It is also credited with alleviating muscle spasms, stress and exhaustion. The gemstone is found mainly in the U.S.A., Russia, Madagascar, Namibia, Zimbabwe and Australia. "