Pollucite was discovered in 1846 and named after Pollux a brother of Helen of Troy in Greek mythology. It is the only mineral were cesium is the essential element. Gems are normally small and under 10cts. in size. Pollucite forms in granite pegmatites as fine grained cubic crystals with vitreous to slightly greasy luster and conchoidal or brittle fracture. Inclusions are usually whitish, resembling spikes or balls or snowflakes. Pollucite is transparent and colorless and is remarkable as one of the few colorless gemstones with a single refractive index (1.52) between 1.50 and 1.70. Pollucite is a keenly collected gemstone species.