Why do some minerals fluoresce in short-wave but not long-wave UV light?
Joe-Speedy’s answer gives a good explanation of what causes fluorescence, but he does not explain why some mineral won’t fluoresce in long-wave UV light, but will in short-wave UV light. The reason for this is because of the nature of light and the energy transitions involved in fluorescence. First of all, let’s look at the nature of light. Light has both wave-like and particle-like properties. In many ways, light behaves like the waves that you see in a body of water. (It spreads out from its origin and can be bent just like waves.) However, the energy of the light seems to be contained in discrete packets that we call photons. The amount of energy that each photon contains is determined by the wavelength of the light. The shorter the wavelength, the more energetic the photon. Now for energy transitions, iIn order to make the transitions that Joe-Speedy described, the electrons have to absorb specific amounts of energy. Electrons can’t absorb random amounts of energy. The must absorb
