A large specimen of rubellite tourmaline, a variety of Elbaite with Pollucite. The Pollucite is very rich in this specimen and is basically all of the colorless Quartz-looking mineral. Rubellite contains about 3% rubidium and is commonly associated with the rare zeolite, Pollucite. Pollucite, the chief ore of cesium, contains about 43% cesium, although it is not that rich at Tanco.
Collected and studied by Dr. David London for his book titled "Pegmatites".