Luminescence is the phenomenon in which a material emits visible light when
subjected to an energy input. There are different types of luminescence. Some
are described below:-
Triboluminescence
Light emitted when a material is struck or broken. Can be seen, in the dark, when some
Feldspars are struck with a geological hammer.
Thermoluminescence
Light emitted when a material is heated. Common examples are metals heated to
'red-heat' and light emitted by molten glass.
Fluorescence
Light emitted when a material is subjected to ultraviolet (UV) radiation. This
is the luminescence of most interest to mineral collectors as many mineral
specimens fluoresce and the colours cover the full spectrum of visible
light, from rich red through brilliant yellows and greens to blue and violet.
