This is the greenish-blue amazonite pebble. Dimensions: 2.7 x 2.4 x 1.8″ (6.8 x 6.2 x 4.5cm). Weight — 8.4oz (238 grams). Origin: Russia, Transbaikalia.
Some information about amazonite:
Amazonite (sometimes called «Amazon stone») is a green variety of microcline feldspar. The name is taken from that of the Amazon River, from which certain green stones were formerly obtained, but it is doubtful whether green feldspar occurs in the Amazon area.
In Russia amazonite is found almost exclusively from the area of Miass in the Ilmensky Mountains, 50 miles southwest of Chelyabinsk, where it occurs in granitic rocks.
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.