Everett Rock and Gem Club

Rocks

Fluorescent minerals emit light when exposed to light or another form of electromagnetic radiation.
The emitted light has a longer wavelength (lower frequency) than the absorbed radiation.
(The emitted light photons have a lower energy than those that are absorbed)
There are over 500 types of fluorescent minerals.
Common fluorescent minerals include fluorite, calcite, opal, selenite, sodalite, and chalcedony.

Luminescence is the ability of a substance to emit light. The source are numerous, a few chemical reactions, radioactivity & light absorption.
Photoluminescence is a form of luminescence that is activated by the absorption of electromagnetic radiation.
Fluorescent minerals are actually photoluminescent
There are two types of photoluminescence: Phosphorescence & Fluorescence
Phosphorescence is characterized by the continued emission of light after the source radiation has been removed.
The lifetime of these emissions is from tens of nanoseconds to seconds.
Like phosphorescent materials, fluorescent materials also continue to emit light after the source radiation is removed,
but they do so for a shorter period of time - from femtoseconds to tens of nanoseconds.

Fluorescent mineral collectors are interested in specimens that emit visible light when exposed to invisible
ultraviolet light due to the resulting magnificent visual effects.
Fluorescent minerals often glow with different colors dependent on the wavelength of the ultraviolet light that
they are exposed to.
There three wavelength bands that are commonly used to classify the ultraviolet light source type:

TYPE OF UV WAVELENTH CLASSIFICATION WAVELENGTH IN NANOMETERS (nm)
---------- ------------------------ -----------------------------
UV-A long wave (LW) 315 - 400
UV-B medium wave (MW) 280 - 315
UV-C short wave (SW) 100 - 280

The most famous fluorescent mineral location is northwest New Jersey
(the mines at Franklin & the Sterling Hill mine).
This area has been named "the fluorescent capital of the world".
The minerals from this region produce the most spectacular displays.
There are over 300 different fluorescent minerals that have been mined in the vicinity of Franklin, New Jersey.
The rarest fluorescent mineral is Benitoite which was only mined at a single location along the San Benito River in California.
That mine has been closed since 2006. Benitoite is the state gem of California.
There are common fluorescent minerals such as calcite & fluorite that are found around the world.

Collecting
Various industrial uses (example: fluorite is used as a flux, for glass & enamel making, and by the chemicals industry)