Fluorescent
Fluorescent minerals glow when exposed to ultraviolet light, emitting visible colours as the energy of the inbound UV light is re-radiated from trace activators or structural defects. This effect can reveal hidden zoning, inclusions and growth patterns and is used in collecting, teaching, and mineral identification. Classic fluorescents include fluorite, calcite, willemite and scheelite. Fluorescence varies by locality, so a mineral from one location may show fluorescence, whereas a specimen from another location may show no response whatsoever. As a result, great care should be taken if trying to identify minerals by fluorescence alone.
