Epidote is a dark green gemstone that can vary in hue from nearly black to a yellow-green. It is also known as Pistacite. Epidote usually appears in a columnar or tubular form that can be prismatic.
Epidote

Epidote is a dark green gemstone that can vary in hue from nearly black to a yellow-green. It is also known as Pistacite. Epidote usually appears in a columnar or tubular form that can be prismatic.