Schorl is a common variety of the tourmaline group of minerals, pitch black and often glossy. Tourmalines are complex aluminium-boron silicate minerals. Other, less frequent tourmalines are elbaite, dravite and uvite, which are translucent and more colorful and used as semi precious and precious stones. Like all tourmalines schorl belongs to the trigonal crystal system and forms straight and elongate columnar crystals