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With few exceptions, most early stone tools were fashioned of quartz.
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Quartz is in igneous and metamorphic
rocks.
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Quartz is in the sediments sand and silt,
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as well as their metamorphosed equivalents
of quartzite and slate.
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‘Chert’ is a term collectively used for all the quartz varieties that have crystals too small to be seen without a microscope. Chert color varieties are:
onyx (mixed white and black), here with rose quartz
flint (gray to black)
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jasper (red to red-brown)
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Chert precipitated from silica-rich groundwater can replace bone and wood present in sediment and sedimentary rocks
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rose quartz
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opal: rough and polished
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Quartz by other names:
amethyst
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citrinetiger’s eye
When chert is struck against iron, it produces a relatively long-lived spark.
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Historically, the single most important use of quartz may have been to start fires.
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Quartz is in building stones.
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Quartz is mixed with clay and
ground-up feldspar, and then fired to form a wide
range of ceramic and porcelain
products.
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Quartz is used in the manufacture of glass
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Quartz is often in concrete and asphalt as aggregate and sand.
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Quartz is used as a flux for metallurgy. A flux is a material that melts easily and can be used to remove impurities from metal ores, or that makes the slag produced by metal ore smelting more fluid.
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Many species of marine plankton, called diatoms, construct their shells of quartz. As these microscopic organisms die, they sink down to cover the deep sea floor with layers of porous diatom shells.
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Diatomaceous earth is the abrasive part of toothpaste. Since it is composed of quartz, the shells are harder than the apatite and calcite minerals that make up our teeth. When you polish your teeth, you actually are grinding the surface down with a very fine abrasive, often the shells of long dead plankton.
Ancient deep sea diatom deposits now exposed at the Earth’s surface are called diatomaceous earth.
Quartz is the abrasive in stonecutting, sandblasting, and scouring soaps
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Pure quartz crystals are piezoelectric – that means that when put under pressure, the crystal produces an electric voltage.
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This characteristic allows quartz crystals to be used to measure pressures or control the frequency of electric impulses, which led to their use in radio systems and timepieces.
Quartz can be a host rocks for gold and other precious metals.
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media rights
Many of the photos in this presentation were obtained through Flickr and Wikipedia.
Funded by FIPSE and by the University of Minnesota. Compiled for Dr. Kent Kirkby, Department of Geology and Geophysics, by Kate Rosok, 2007. Each displayed image
retains its original media rights. For educational purposes only; not to be used commercially.
public domain (none)
© Copyright. All rights reserved
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