This energy pulse caused by the uv-light moves an electron to a higher peel, but the electron can not hold his position, and shoot back to its former position. The whole process is a part of the lost energy ( Heat). These lower energy released now has a frequency which is visible. This broadcast from sight by all imaginable colors. The mineral is a light source! This is called fluorescence.
What are the causes of fluorescence?
The tendency to fluoresce it is especially bad conductors. Almost all minerals with metallic luster or submetalic not!
The purer the mineral, the less chance of fluorescentiron, nickel, cobalt or copper minerals (> 1%): hardly! Impurities (contamination of other substances)
Uranyl ion (UO2) 2+ in e.g. Opal and chalcedony
manganese (Mn 2+) ion is one of the most-important causes of fluorescence. Chromium (Cr 3+) in emerald or Disulfide ion (S2) into sodalite
Intrinsic factors (internal factors due to the presence of certain elements in the molecules).
Uranyl ion (UO2) 2+ titanium Lead and mercury, certain ions (WO4) 2 (Tung State ion) or (Moo4) 2 Molhybdate