Are all rocks fluorescent and how can I see the glow at home?

This week's question comes up many times at rock collecting shows and was asked this week.  Are all rocks fluorescent and how can I see them glow at home?

All minerals have the ability to reflect light. That is what makes them visible to the human eye. Most minerals however, do not fluoresce.  Only about 15% of minerals have an interesting physical property known as "fluorescence". These minerals have the ability to temporarily absorb a small amount of light and an instant later release a small amount of light of a different wavelength. This change in wavelength causes a temporary color change of the mineral in the eye of a human observer.

The color change of fluorescent minerals is most spectacular when they are illuminated in darkness by ultraviolet light (which is not visible to humans) and they release visible light. The photograph above is an example of this phenomenon.

Fluorescence in minerals occurs when a specimen is illuminated with specific wavelengths of light. Ultraviolet light, x-rays and cathode rays are the typical types of light that trigger fluorescence. These types of light have the ability to excite susceptible electrons within the atomic structure of the mineral. These excited electrons temporarily jump up to a higher orbital within the mineral's atomic structure. When those electrons fall back down to their original orbital a small amount of energy is released in the form of light. This release of light is known as fluorescence. 

In order to see this spectacular vision at home, we have home based ultraviolet lamps.   These come in different wavelengths which are needed for certain specimens.  There are 3 wavelengths known to cause this fluorescence: Shortwave (254nm), Midwave (315nm) and Longwave (400nm). Longwave UV is very close to what you have possibly seen in stores as a "black light", and is the least expensive method. 

The vast majority of fluorescent minerals fluoresce under Shortwave UV Lamps.  We carry both battery operated and plug-in models of these types of UV lamps.  Scientists actually utilize these lamps to help them identify specimens.  Ideally, you can also get these types of Ultraviolet Lamps with Filters placed on them to filter out more visible light.  However, these filters are very expensive.  To get at least some home enjoyment out of your fluorescent rocks, we suggest picking up one of our Ultraviolet Lamps so you can see for yourself what types you have!