With bands of pyrite or fools gold, this is Black Gold Amazonite. Amazonite is a rare blue-green variety of microcline (a feldspar mineral) that is used as a semiprecious stone. It's relative hardness is 6 - 6.5. From the same group comes the other three well known feldspars. Labradorite, sunstone and moonstone. It is opaque. These stones are from Southern Africa.