Amazonite

Amazonite is a blue-green variety of microcline, a mineral of the potassium feldspar family. Its color ranges from turquoise green to greenish blue, and it often shows pale streaks and a fine grid of lines.

The name is misleading. It comes from the Amazon River, because certain green stones were once believed to come from there. In fact, there are no amazonite deposits in the Amazon region. One of the oldest branding mistakes in the mineral world.

For a long time the color was blamed on copper. A 1985 study showed that it comes from small amounts of lead and water within the feldspar's crystal structure, with iron and other elements playing a smaller part.

People have been making jewelry from amazonite for more than three thousand years. Archaeological finds show it was used in Middle and New Kingdom Egypt and in Mesopotamia.

Amazonite forms in granitic pegmatites, coarse-grained rocks that crystallize in the last stages of cooling magma. Known deposits include Colorado in the United States, Russia, Ethiopia and South Africa. The Morefield Mine in Virginia is considered the source of the best amazonite in the United States.