(From FB Discussion Group - 5/1/2017)
I saw a video on reddit which illustrated triboluminescence very effectively and I posted it to the Fluorescent Mineral Facebook Group. Several excellent comments were made and I learned something: most of the light generated is in the UV range. Comments and discussion below.
This gif was posted to imgur. I did some investigation and found the original on YouTube. This fellow posts some really interesting science videos - worth viewing in their entirety.
Justin B. - Worth noting: if you want to try this at home, they have to be Wint-o-green lifesavers, not pep-o-mint. The oil of wintergreen (methyl salicylate) is fluorescent, and the sugar breaking produces UV light, causing the methyl salicylate to fluoresce. Pep-o-mint lifesavers will produce light, but they do not fluoresce nearly as much so won't be nearly as bright. Michael I - I wasn't aware that the energy released was in UV. So the visible effect has always been the fluorescence of the oil? Makes it far cooler! Philip N. - Triboluminescence is a fascinating phenomenon...seems to be a catch all for several different physical effects. Generation of radiation be mechanical disruption of bonds ((as proposed for this example) is one of them (x-rays can be generated by stretching scotch tape as well). There are also mechanisms proposed that involve generation of static electricity and intracrystalline bond manipulation. What i find interesting is that most of the mineralogical examples appear to the eye to have similar spectral characteristics (give off an orange light as I see it). Curious if others see the same thing, or know of examples that deviate from this. Mark C. - Interesting comments - I did not know that most of the light generated was in the UV range, good to know. Now we have a substitute for our UV lights ;-). With a little reading it seems that it's not always fluorescence which we see in all materials. A little visible light is also produced - in the case of quartz perhaps what we are seeing is the visible light? Most of the visible light is at the low end of the spectrum, thus it appears bluish in no-fluorescent materials (I'm assuming). But sphalerite is yellow/orange when hit/rubbed/scratched. Would that color be the result of the very fluorescent sphalerite reacting to the UV? (nice pic of this)