Fluorite

Fluorite, also called fluorspar, is calcium fluoride, a cubic halide mineral with a hardness of four on the Mohs scale. Pure fluorite is colourless, and impurities give it its many colours. Wikipedia says the name comes from a Latin word for flowing and that the mineral was first printed about in 1530 by Agricola. Cunningham calls it one of the New Age stones with little history of magical use, of projective energy, and says it works with the conscious mind, straightening thoughts and sharpening analysis. Hall calls it highly protective on a psychic level and a cleanser and purifier, and associates it with grounding spiritual energies, intuition, order, self-confidence, truth and learning. She also says it needs cleansing after each use. These are the authors' claims, not established fact.