This labradorite is from the Southwestern Region in the Tulear Province of Madagascar. Some of the best material known and marketed is from this locale. Labradorite is a variety of plagioclase feldspar. It is a silicate that contains the elements Al, Ca, Na and Si. It can be formed when large crystals or phenocrysts within an igneous rock, such as some granites, basalts and gabbros contain feldspar phenocrysts. Like some feldspars, such as moonstone, sanadine and labradorite, when they are properly oriented to light they have an iridescence called a Schiller effect. This particular piece has a gemstone quality with large surface areas of iridescence. It has a free form shape that was cut and polished to expose the maximum affect within the stone. It measures 6 1/2 x 3 3/4 x 3 inches or 165 x 95 x 76. It weighs 3 pounds 12 ounces.