of Triboluminescence is not fully understood, but appears to be caused by the separation and
reunification of electrical charges. The term comes from the Greek word τριβείν meaning
to rub and the Latin word lumen meaning
light. There are only a handful of gem type of minerals that
may display triboluminescence.
Triboluminescence is often used as a synonym for fractoluminescence (a
term sometimes used when referring only to light emitted from fractured
crystals). Triboluminescence differs from piezoluminescence in that a piezoluminescent material emits light when it is deformed, as opposed to broken. These are examples of mechanoluminescence, which is luminescence resulting from any mechanical action on a solid.
The Uncompahgre Ute Indians of Central Colorado,
USA are one of the first documented groups of people in the world credited with the application of mechanoluminescence
involving the use of quartz crystals to generate light. The Ute
constructed special ceremonial rattles made from buffalo rawhide which
they filled with clear quartz crystals collected from the mountains of
Colorado and Utah. When the rattles were shaken at night during
ceremonies, the friction and mechanical stress of the quartz crystals
impacting together produced flashes of light visible through the
translucent buffalo hide.
The first recorded observation is attributed to English scholar Francis Bacon when he recorded in his 1620 Novum Organum that "It is well known that all sugar, whether candied or plain, if it be hard, will sparkle when broken or scraped in the dark." The scientist Robert Boyle also reported on some of his work on triboluminescence in 1663. In the late 1790s, sugar
production began to produce more refined sugar crystals. These crystals
were formed into a large solid cone for transport and sale. This solid
cone of sugar had to be broken into usable chunks using a device known
as sugar nips. People began to notice that as sugar was "nipped" in low light, tiny bursts of light were visible.
A historically important instance of triboluminscene occurred in Paris in 1675. Astronomer Jean-Felix Picard observed that his barometer
was glowing in the dark as he carried it. His barometer consisted of a
glass tube that was partially filled with mercury. Whenever the mercury
slid down the glass tube, the empty space above the mercury would glow.
While investigating this phenomenon, researchers discovered that static
electricity could cause low-pressure air to glow. This discovery
revealed the possibility of electric lighting.
science behind Triboluminescence
have not yet arrived at a full understanding of the effect, but the
current theory of triboluminescence — based upon crystallographic,
spectroscopic, and other experimental evidence — is that upon fracture
of asymmetrical materials, charge
is separated. When the charges recombine, the electric discharge
ionizes the surrounding air, causing a flash of light. Research further
suggests that crystals which display triboluminescence must lack
symmetry (in order to permit charge separation) and be poor conductors.
However, there are substances which break this rule, and which do not
possess asymmetry, yet display triboluminescence anyway. It is thought
that these materials contain impurities, which confer properties of
asymmetry to the substance. Much of the recent work on triboluminescence
was done by Linda M. Sweeting at Towson University.
As mentioned above, triboluminescence can be observed when breaking sugar crystals,
especially Wint-O-Green Life Savers, in the dark. Ordinary friction tape (the cloth type -
not the shiny electrician's tape) displays a glowing line where the end of the tape is being pulled away from the roll. In 1953, Russian scientists showed that triboluminescence caused by peeling a roll of Scotch Tape in a vacuum can produce energy equivalent to X-rays.
In 2008, scientists working at UCLA performed an experiment that showed
actual X-rays were produced, which were strong enough to leave an X-ray
image of a finger on dental photographic paper; they hoped to use their research to create a new type of x-ray imaging device.