Lake George Amazonite

Description

This Amazonite (K,Al,Si,O) is from Lake George, Colorado. In addition to Lake George, Amazonite can also be found in Arapahoe, Custer, Douglas County, El Paso, Park, and Teller Counties within Colorado, in 18 other States, and on nearly every Continent, in or near pegmatites, metamorphic rock, and granite.

Amazonite, aka Amazonstone, a blue variety of Microcline and K-feldspar, was named in 1847 after a green stone collected near the Amazon river. According to wikipedia, “though, it is unknown whether those stones were amazonite. 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.”

Also from wikipedia, “For many years, the source of Amazonite’s color was a mystery. Some people assumed the color was due to copper because copper compounds often have blue and green colors. A 1985 study suggests that the blue-green color results from quantities of lead and water in the feldspar. Subsequent 1998 theoretical studies by A. Julg expand on the potential role of aliovalent lead in the color of microcline. Other studies suggest the colors are associated with the increasing content of lead, rubidium, and thallium ranging in amounts between 0.00X and 0.0X in the feldspars, with even extremely high contents of PbO, lead monoxide, (1% or more) known from the literature. A 2010 study also implicated the role of divalent iron in the green coloration. These studies and associated hypotheses indicate the complex nature of the color in amazonite; in other words, the color may be the aggregate effect of several mutually inclusive and necessary factors.”

The last interesting bit learned from wikipedia was that in 2021, the German Institut für Edelsteinprüfung found that after testing Amazonite with an acid simulating saliva, as though a child were to swallow this, more than five times the recommended amount of lead would be absorbed. So, it might be a pretty rock, but don’t let little children play with it.