Which mineral gave its name to the phenomenon of fluorescence?

Fluorite gave its name to the phenomenon of fluorescence.

Fluorite is a mineral composed mainly of calcium fluoride, with the chemical formula CaF₂. It occurs in many colors, including purple, green, yellow, blue, and colorless varieties. Some fluorite specimens glow visibly under ultraviolet light because impurities or defects in their crystal structure absorb ultraviolet energy and re-emit part of it as visible light.

The word fluorescence was coined from fluorite after this striking behavior was observed. Not every fluorite specimen fluoresces, and the color and intensity of the glow can vary substantially. Blue or violet ultraviolet lamps are commonly used to examine fluorescent minerals.

Fluorite is also important industrially. It is a major source of fluorine and is used as a flux in metal processing, helping molten materials flow more easily. Clear, optically suitable fluorite has been used in specialized lenses because it can reduce certain optical distortions. Fluorescence is not the same as phosphorescence: fluorescence generally stops almost immediately when the ultraviolet source is removed.