Moonstone is named for the interesting play of light as its reflested in many directions at once from the alternating layers of different feldspars within, a phenomenon called adularescence. Adularia is the most common moonstone mineral, but oligoclase, and less commonly albite and labradorite, among the plagioclase feldspar group also produce moonstone specimens.
Polishing: Moonstone is absolutely beautiful when polished. Colors range from almost white, to red, to deep brown, all with the characteristic adularescence. The stone can be brittle, so a cushioning medium is recommended, but do not use the same media from stage to stage or you'll get contamination.