This is an attractive Amazonite pendant, with a sterling silver bail and sterling necklace.
Amazonite (sometimes called "Amazon stone") is a green variety of microcline feldspar. Amazonite is a moderately rare mineral. Formerly, it was obtained almost exclusively from the area of Miass in the Ilmensky Mountains, in Russia, where it occurs in granitic rocks. More recently, high-quality crystals have been obtained from Pike's Peak, Colorado.
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.
(As always, if you don't like the choice of bail or necklace, just contact me and we can make changes.)