Hold firm pressure while you quickly drag one pebble across the surface of the other. If you do this properly and if you have pieces of quartz that are triboluminescent, you will see a brief flash of light that penetrates deeply into the translucent quartz. Experiment with different speeds, different amounts of pressure, and directions of drag to maximize the flash of light. Some specimens will also produce small amounts of light if you bang them together or rub them against one another.
You can also experiment with different minerals to see if they are triboluminescent. You will probably find many minerals that exhibit the property. The best way to learn about minerals is to study with a collection of small specimens that you can handle, examine, and observe their properties.
Inexpensive mineral collections are available in the Geology. Triboluminescence is present in quartz; however, the strength of the phenomenon varies from specimen to specimen. Triboluminescence is well known in sphalerite , fluorite , calcite , muscovite , and many feldspar minerals.
Some specimens of common opal produce a bright orange flash. Test a few specimens yourself. Don't forget to wear safety glasses, and be aware that this test will scratch your specimens. You will probably discover lots of specimens of various minerals that are triboluminescent. We have found that the flash of light is brightest when we use specimens that are transparent or very translucent. These specimens allow the light to penetrate deeply, making the flash easier to observe.
For years we have observed flashes of light while cutting lapidary rough on a rock saw or shaping it on a diamond wheel. We originally thought this light was incandescence an emission of light from a hot object , but now we think that at least some of that light was triboluminescence. Triboluminescence is not a good property to use for mineral identification. Some specimens of a mineral might exhibit the property and other specimens will not. The phenomenon of triboluminescence is poorly understood.
Some researchers believe that scratching or hitting materials together provides an input of energy that excites electrons within the materials. This has been used in many interesting ways, most commonly the crystal oscillator. As it vibrates in such a precise frequency, it can be used to keep track of time as in quartz wristwatches or digital clocks in computers and mobile phones, or to provide a stable frequency for radio communications.
Use the button to select a material and get started. This website places cookies on your computer to improve your experience. By continuing to browse the site, you are agreeing to our use of cookies. For more details, see our cookie policy. Name E-mail. Chances are good they are quartz. Triboluminescence sometimes is called "cold light" because no heat is produced.
Material scientists believe the light results from a recombination of electrical charges that become separated when crystals are fractured. When the charges get back together, the air is ionized, producing a flash of light. Usually, materials that display triboluminescence are displayed an asymmetrical structure and are poor conductors. This is not a hard-and-fast rule, however, since other substances display the effect.
It's not restricted to inorganic materials, either, since triboluminescence has been observed between vertebral joints, during blood circulation, and even during sexual intercourse. If it's true the light results from ionization of air, you might expect all forms of triboluminescence in the air to produce the same color of light. However, many materials contain fluorescent substances that release photons when excited by the energy from triboluminescence.
Thus, you can find examples of triboluminescence in just about any color. Rubbing together diamonds or quartz is not the only easy way to observe triboluminescence.
You can view the phenomenon by pulling apart two pieces of duck tape , by crushing wintergreen candies , or by pulling the Scotch tape from its roll which also produces x-rays. The triboluminescence from the tape and the candies is a blue light, while the light from fracturing quartz is a yellow-orange.
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