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How Does Garnet Form?
Garnet in Metamorphic Rocks Most garnet forms at convergent plate boundaries where shale is being acted upon by regional metamorphism. The heat and pressure of metamorphism breaks chemical bonds and causes minerals to recrystallize into structures that are stable under the new temperature-pressure environment. The aluminum garnet, almandine, generally forms in this environment. As these rocks are metamorphosed, the garnets start as…
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Garnet Physical and Chemical Properties
The most commonly encountered minerals in the garnet group include almandine, pyrope, spessartine, andradite, grossular, and uvarovite. They all have a vitreous luster, a transparent-to-translucent diaphaneity, a brittle tenacity, and a lack of cleavage. They can be found as individual crystals, stream-worn pebbles, granular aggregates, and massive occurrences. Their chemical composition, specific gravity, hardness, and colors…
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What is Garnet?
Garnet is the name used for a large group of rock-forming minerals. These minerals share a common crystal structure and a generalized chemical composition of X3Y2(SiO4)3. In that composition, “X” can be Ca, Mg, Fe2+ or Mn2+, and “Y” can be Al, Fe3+, Mn3+, V3+ or Cr3+. These minerals are found throughout the world in metamorphic, igneous, and sedimentary rocks. Most garnet found near…
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Tripoli
Tripoli is crystalline silica of an extremely fine grain size (less than ten micrometers). Commercial tripoli is a nearly pure silica material that is used for a variety of mild abrasive purposes which include: soaps, toothpastes, metal-polishing compounds, jewelry-polishing compounds, and buffing compounds. It can be used as a polish when making tumbled stones in a rock tumbler.…
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Quartz as a Gemstone
Quartz makes an excellent gemstone. It is hard, durable, and usually accepts a brilliant polish. Popular varieties of quartz that are widely used as gems include: amethyst, citrine, rose quartz, smoky quartz, and aventurine. Agate and jasper are also varieties of quartz with a microcrystalline structure. Special Silica Stone Uses “Silica stone” is an industrial term for materials such as quartzite, novaculite,…
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A Need for Synthetic Quartz Crystals
During the 1900s the demand for high-quality quartz crystals accelerated so rapidly that mining operations around the world were unable to supply them in adequate quantities. Fortunately, this need was realized during World War II, and military and private industry began working on methods to grow synthetic quartz crystals to meet the special requirements of…
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Many Other Quartz Sand Uses
Quartz sand is used as a filler in the manufacture of rubber, paint, and putty. Screened and washed, carefully sized quartz grains are used as filter media and roofing granules. Quartz sands are used for traction in the railroad and mining industries. These sands are also used in recreation on golf courses, volleyball courts, baseball…
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Uses in the Petroleum Industry
Quartz sand has a high resistance to being crushed. In the petroleum industry, sand slurries are forced down oil and gas wells under very high pressures in a process known as hydraulic fracturing. This high pressure fractures the reservoir rocks, and the sandy slurry injects into the fractures. The durable sand grains hold the fractures open after the…
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Uses of Quartz as an Abrasive
The high hardness of quartz, seven on the Mohs Scale, makes it harder than most other natural substances. As such it is an excellent abrasive material. Quartz sands and finely ground silica sand are used for sand blasting, scouring cleansers, grinding media, and grit for sanding and sawing. Chert: Chert is a microcrystalline or cryptocrystalline quartz.…
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Uses of Quartz in Glass Making
Geological processes have occasionally deposited sands that are composed of almost 100% quartz grains. These deposits have been identified and produced as sources of high-purity silica sand. These sands are used in the glassmaking industry. Quartz sand is used in the production of container glass, flat plate glass, specialty glass, and fiberglass.