Ultraviolet (UV) light causes some minerals to fluoresce. Saleeite is one of these. So I got to thinking...how would a mineral that fluoresces under UV go under a different light source, in this case, a blue light emitting diode (LED) on a pen.
The result is not too bad. The greenish-yellow crystal is the saleeite and the blue crystals around it are orthoclase feldspar (the specimen is from Lake Boga in Victoria by the way).
I obviously got a little bit bored tonight!