Fluorescent minerals

Fluorescent minerals

Description

Minerals that have the unique physical property to absorb light and one wavelength and instantaneously release it at a different wavelength, resulting in a temporary color change to the eye of the human observer. Only about 15% of minerals are able to fluoresce. The fluorescence is usually due to a cation activator, such as: tungsten, molybdenum, lead, boron, titanium, manganese, uranium, and chromium, but some rare earth elements are also able to contribute to the phenomenon. Some trace elements, such as iron or copper, can quench the fluorscence. Most minerals fluoresce a single color, but some may have multiple colors; for example calcite can fluoresce red, blue, white, pink, green and orange. Because of the potential for many varying factors, the fluorescence of mineral is not typically used for its identification.

• Phosphorescence:

While fluorescent minerals stop glowing when the light source is turned off, minerals that are phosphorescent continue to emit light. Minerals that can sometimes exhibit phosphorescence are: calcite, celestite, colemanite, fluorite, sphalerite, and willemite.

• Thermoluminescence:

Heating a mineral to temperatures as low as 50-200 degrees Celsius may also produce the emission of light. Some minerals that exhibit thermoluminescence are: apatite, calcite, chlorophane, fluorite, lepidolite, scapolite, and some feldspars.

• Triboluminescence:

Additionally, some mineral may emit light due to a mechanical energy, such as striking, crushing, or scratching. Potential triboluminescent minerals are: amblygonite, calcite, fluorite, lepidolite, pectolite, quartz, sphalerite, and some feldspars.

Examples

Mineral	Composition	Visible color	Fluorescent color
Apatite	Ca5(PO4)3(F,Cl,OH)	pale green to purple	pink, blue, greenish yellow
Calcite	CaCO3	colorless to white	red, blue, pink, green, orange
Cerrusite	PbCO3	colorless to white	yellowish
Chalcedony	SiO2	white, blue, pink	variable
Corundum	Al2O3	red (ruby), blue (sapphire)	red (ruby), none (sapphire)
Fluorite	CaF2	colorless, white, pale blue, green	blue-violet
Quartz	SiO2	colorless, purple	variable
Scheelite	CaWO4	colorless, white, gray brown, yellow, orange, red, green	bright blue, white, yellow
Sphalerite	(Zn,Fe)S	yellow, brown, gray, black	lighter specimens = yellowish
Willemite	Zn2SiO4	colorless, white, gray, red, brown	strong white, green

Comparisons

Properties of Common Abrasives

Properties of Common Gemstones

Natural and Simulated Diamonds