See Some Triboluminescence Examples

You may be familiar with the Wint-O-Green Lifesaver™ 'spark in the dark', but if you don't have Lifesavers handy, there are other ways you can see triboluminescence. Triboluminescence results from the fracture of (usually) asymmetrical materials. The break separates electrical charges, which recombine and ionize the air. The ionization of nitrogen in the air produces ultraviolet light, but you can't see that. You can observe triboluminescence when another material is present that absorbs that ultraviolet light and re-releases it in the visible range (fluoresces). Here are some examples:

• Cracking Wint-O-Green Lifesavers
  Crush a wintergreen-flavored Lifesaver candy with your teeth or a hammer. You get triboluminescence whenever you smash sugar, but there usually isn't enough light for you to see it. The methyl salicylate in the wintergreen oil is fluorescent and converts the ultraviolet light into blue light. If you can't find this flavor of Lifesavers, you can use sugar with wintergreen oil or clove oil.
• Unwapping a Band-Aid™
  Some Band-Aid wrappers will emit a blue-green glow when they are unwrapped quickly. While you can unwrap the bandage in the dark, you'll probably want to turn the lights back on before applying to a wound!
• Cutting a Diamond
  This is not something most of us are likely to do, but some diamonds will fluoresce blue or red when being rubbed or, more usually, cut.
• Unrolling Friction Tape
  Friction tape is that cloth tape that has a rubber adhesive such that it is sticky on both sides. It can be used as an electrical insulator, but you'll usually see it in the context of sports, to wrap hockey sticks, tennis rackets, baseball bats, etc. If you unroll friction tape in the dark you'll observe a glowing line as the tape is pulled away from the roll.
• Opening Sealed Envelopes
  The adhesive used to seal some envelopes will fluoresce blue as the contact is broken.
• Remove Ice from the Freezer
  This is an example of fractoluminescence, which is sometimes considers synonymous with triboluminescence. Fractoluminescence is light produced by fracturing a crystal. The fracture separates charge. If enough charge is separated, an electrical discharge may occur across the gap. If you remove ice from a freezer in a dark room, you may see flashes of white light accompanying the crackling sounds of ice undergoing rapid thermal expansion.