Schorl and Dravite are separate minerals, but are commonly categorized just by their color. Elbaite is an independent member of the Tourmaline group, and its color varies greatly. In the gem trade, however, Elbaite refers to green Tourmaline, and Tourmaline by itself also refers to green Tourmaline. About Tourmaline - Tourmaline is a very popular gemstone and collectors mineral. It exists in all colors and the multi-colored stones are unsurpassed in splendor.
Tourmaline is pyroelectric and piezoelectric.
If you were to put a Tourmaline specimen under great pressure or temperature change it will generate an electrical charge. Dust particles will become attached to the crystals ends when charged. When viewed from the ends the crystal color may be different from the outer color or may be deeper in color. And certain Tourmalines may have a cat's eye effect. And as luck will have it, it just so happens Tourmaline is the national gemstone of the United States.