Fluorescent Minerals: The World of UV Hunting

Some minerals have the amazing ability to absorb ultraviolet light and release it as visible light, causing them to glow in the dark. This is called fluorescence. It's a magical way to experience rockhounding and can reveal specimens you'd walk right past in the daytime.

There are two main types of UV lights used by collectors. Longwave (365nm) is cheaper and safer; it makes minerals like sodalite (yooperlites) and some calcites glow. Shortwave (254nm) is more expensive and requires eye protection, but it triggers fluorescence in a much wider range of minerals, including willemite and scheelite.

Franklin, New Jersey is the fluorescent mineral capital of the world, with over 80 fluorescent species. In the west, many locations produce fluorescent hyalite opal (green), calcite (red/orange), and scheelite (blue/white).

UV light is radiation. Shortwave UV can damage your eyes and skin (like a sunburn). Always wear UV-blocking safety glasses when using shortwave lamps, and avoid shining them on your skin or at others.