Fluorescent minerals are minerals which emit visible light (fluorescence) when illuminated by invisible ultraviolet (UV) radiation.

Roughly 10% of all mineral species will fluoresce, though few do so brightly, or even consistently.

Specimens of the same species from one locale may glow, yet those from another will not. Some species glow different colors, again depending on the location found.

Much fluorescence is due to trace amounts of chemical impurities which helps explain the variable nature of the phenomenon.

The change in appearance from what may be a dull, ugly specimen in daylight, to a vivid luminous object under ultraviolet, is nothing short of amazing.

Additionally, a few minerals give specimens with different colored fluorescent responses to different wavelengths of ultraviolet.

For collectors of fluorescent minerals, there are a few 'special' locations where a great variety or quantity or both occur.

These include the twin Zn-Mn-Fe deposits in the northwest corner of New Jersey, Franklin and Sterling Hill; and the Ilímaussaq alkaline complex in South West Greenland. Each yields countless specimens in a practically limitless range of vivid colors and patterns.

For additional information on these fluorescent minerals and a lengthy account of fluorescent collecting at Ilímaussaq please visit out sister sites franklin-sterlinghill.com and luminousminerals.com.

Calcite cleavage rhombs in daylight (left) and fluorescing under shortwave UV (right). The one glowing red is from Franklin, NJ and the one glowing bluish-white is from Nuevo Leon, Mexico.

Close-up view of a complex multi-color fluorescent specimen from Ilímaussaq, Greenland. Shown under shortwave UV. Width 2 cm.

Fine specimen of platy margarosanite and wollastonite fluorescing under shortwave UV. Franklin, NJ.