Definition of fluorescence

i. The emission of visible light by a substance exposed to ultraviolet light. It is a useful property in examining well cuttings for oil shows and in prospecting for some minerals.

Ref: AGI

ii. The absorption of radiation at one wavelength, or a range of wavelengths, and its reemission as radiation of longer, visible wavelengths.

iii. A type of luminescence in which the emission of light ceases when the external stimulus ceases; also, the light so produced.

Ref: AGI

iv. Quantized electromagnetic radiation as a material drops from a higher to a lower energy state. Fluorescence stops when the excitation energy stops.

Fluorescent minerals and other substances are those showing noticeable fluorescence when exposed to ultraviolet light, and include scheelite, autunite, willemite, many fluorites, calcite, etc.; note however that many minerals only fluoresce strongly under certain wavelengths.

Compare with: phosphorescence, luminescence