As a mineral name, quartz refers to a specific chemical compound silicon dioxide, or silica, SiO 2 , having a specific crystalline form hexagonal. It is found in all forms of rock: igneous, metamorphic and sedimentary. Quartz is physically and chemically resistant to weathering. When quartz-bearing rocks become weathered and eroded, the grains of resistant quartz are concentrated in the soil, in rivers, and on beaches.
The white sands typically found in river beds and on beaches are usually composed mainly of quartz, with some white or pink feldspar as well.
Pure quartz is clear. Native peoples of Indiana used quartz for many vital tasks. Today quartz is used in many products as a raw material for huge amounts of construction materials, such as glass, concrete, or mortar, and quartz is refined to yield silicon which is critical for computers and other high technology mainstay of modern life Fig.
Quartz is still used for many modern Industrial materials Fig. Quartz is made when atoms of silicon and oxygen bind in the form of a tetrahedron.
The nature of the atoms and the resulting crystal structure Fig. Quartz has a scratch hardness of 7 and often forms hard, tough fragments that withstand all sorts of mechanical and chemical attacks. Crystals form clear hexagonal 6-sided forms when space allows Fig. Quartz is a major component of many types of rock.
Quartz is abundant in certain igneous rocks. It forms the clear to grey or even white lumpy blobs in granite and comprise most of silicate-rich or felsic igneous rocks. It is absent or rare in more primitive basic or silica-poor igneous rocks such as basalt.
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What Are the Products of the Chemical Weathering of How Is Rose Quartz Formed? What Is Magnesium Carbonate? Quartz makes up about 12 percent of the land surface and about 20 percent of the Earth's crust. Most of the remaining crustal rocks are rich in silicate minerals which include silicon and oxygen together with other elements.
Quartz is divided into two groups; crystalline or visible crystals and cryptocrystalline or hidden crystals which, require a microscope. Crystalline quartz is found as tiny crystal frostings sparkling on a rock surface as well as well-formed crystals weighing tonnes. Quartz crystals are named from the colour of the crystals:. Pink — rose- tiny amounts of titanium oxide crystals rutile give it the pink colour.
Yellow, brown and black — smoky quartz— natural radiation in the rocks causes colouration. Crystalline quartz is the most common weathering-resistant mineral. This explains its presence as the main ingredient in beach sand. In some parts of the world beach sand has a thin layer of silica gel on the outside.
This causes the sand to squeak when walked on. Birds migrating from Canada to warmer climates in the fall take with them quartz sand grains in their crops. These sand grains are found in areas where no other deposits of sand are to be found. Banded agate is formed by the deposition of silicon dioxide from a hot water solution. Tiny amounts of iron and other impurities give it a variety of colours. Most of the bright colours of agate pink, green, blue are formed by dyeing grey and white banded agate.
Some brown agates are coloured by heating.
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