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Triboluminescence in Minerals
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…
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What is Triboluminescence?
Triboluminescence is a flash of light produced when a material is subjected to friction, impact or breakage. The phenomenon is also known as fractoluminescence and mechanoluminescence. Triboluminescence is common in minerals. About 50% of crystalline materials are thought to exhibit the property. It is also observed in many noncrystalline materials [1]. How to Demonstrate Triboluminescence ****…
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What Is Sugilite?
Sugilite is a rare mineral and a gemstone best known for its vibrant pink to purple colors. High-quality specimens are sought after by mineral collectors and lapidarists (people who cut and polish gems). Sugilite is a sodium potassium lithium silicate mineral. Small amounts of manganese produce the pink to purple color displayed by some specimens of sugilite. Its chemical composition is as…
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Other Uses of Corundum
Corundum has many other uses. It is chemically inert and resistant to heat. These properties make it a perfect material for making refractory products such as fire brick, kiln liners, and kiln furniture. Today, these products are usually made with synthetic corundum. Pure corundum is colorless, transparent, durable, and scratch resistant. Large crystals of clear…
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Ruby Lasers
Synthetic corundum is an essential part of many lasers. In fact, the first working laser was a “ruby laser,” made by Theodore Maiman at Hughes Research Labs in 1960. It employed a synthetic ruby crystal as the “gain medium.” The gain medium is a material in the laser that is the target of an intense…
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Uses of Limonite
Limonite has been used by people since prehistoric times. Their first use of limonite was probably as a pigment. It is found in many Neolithic pictographs, and throughout history it has been one of the most important pigments for creating paints in the yellow to brown color range known as ocher. Its use as a pigment…
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“Jewels” and “Crystals” in Watches
In the mid-1800s, watch makers in Switzerland needed tiny bearings that were highly resistant to abrasion. They discovered that they could drill a hole into a tiny piece of corundum and use it for a smooth-running, long-life bearing. The corundum was much harder than the metals used to make the moving parts of a watch,…
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Use as a Gemstone
In the gemstone and jewelry market, almost all of the attention goes to a small group of gems known as “the big four”: diamond, ruby, sapphire, and emerald. Two of these, ruby and sapphire, are gem corundums. These most popular gems are highly sought after and have been mined in many parts of the world for thousands of years. Today, millions…
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Geologic Occurrence
Limonite usually occurs as a secondary material, formed from the weathering of hematite, magnetite, pyrite, and other iron-bearing materials. Limonite is often stalactitic, reniform, botryoidal, or mammillary in habit, rather than crystalline. It also occurs as pseudomorphs and coatings on the walls of fractures and cavities. Some limonite is found in stratified deposits where hydrous iron oxides form as…
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Emery
Emery stone is a granular metamorphic or igneous rock that is rich in corundum. It is a mixture of oxide minerals, typically corundum, magnetite, spinel and/or hematite. It is the most common form of natural corundum that has been used to manufacture abrasives. The use of emery as an abrasive has declined significantly in the last several decades. It…