With bands of pyrite or "Fool's 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.