Amazonite, also known as Amazon stone, is a green tectosilicate mineral, a variety of the potassium feldspar called microcline.
Its name taken from that of the Amazon River, from which green stones formerly obtained, though it is unknown whether those stones were amazonite. It first described as a distinct mineral only in the 18th century.
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.