Fluorite is a popular mineral made from calcium and fluorine and comes in many pretty colors--often banded like agates. The gems in this video are a green fluorite mushroom and a blue-violet fluorite tower.
You may have heard the term, fluorescent, before. All minerals can reflect light, but many have the ability to fluoresce as well--essentially glowing under UV light.
In minerals that fluoresce, this happens when a specimen is illuminated with certain types of wavelengths of UV light, x-rays, and even cathode rays. In the video, I'm using a long wave UV light by Nitecore.
In the video, I commented that the fluorite tower didn't seem to be fluorescing, but upon a second look, it actually does seem to fluoresce instead of reflecting the UV light.
Geology.com calls Fluorite the original fluorescent mineral and this is due to George Gabriel stokes noticing that fluorite produces a blue glow when illuminated with "invisible light beyond the violet end of the spectrum." He named this phenomenon "fluorescence" after the mineral fluorite.
I have one piece of Fluorite jewelry that also fluoresces--a green fluorite pendant for $20.