What is Quartzite?
ANSWER-Quartzite (from German Quarzit) is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colors, such as yellow, green, blue and orange, are due to other mineral impurities.
Orthoquartzite is a very pure quartz sandstone composed of usually well rounded quartz grains cemented by silica Orthoquartzite is often 99% SiO2 with only very minor amounts of iron oxide and trace resistant minerals such as zircon, rutile and magnetite. Although few fossils are normally present, the original texture and sedimentary structures are preserved.
In true metamorphic quartzite, also called meta-quartzite, the individual quartz grains have recrystalized along with the former cementing material to form an interlocking mosaic of quartz crystals. Minor amounts of former cementing materials, iron oxide, carbonate and clay, are often recrystalized and have migrated under the pressure to form streaks and lenses within the quartzite. Virtually all original textures and structure have usually been erased by the metamorphism.
USES
Because of its hardness and angular shape, crushed quartzite is often used as railway ballast. Quartzite is a decorative stone and may be used to cover walls, as roofing tiles, as flooring, and stair steps. Its use for countertops in kitchens is expanding rapidly. It is harder and more resistant to stains than granite. Crushed quartzite is sometimes used in road construction. High purity quartzite is used to produce ferrosilicon, industrial silica sand, silicon and silicon carbide .During the Stone Age quartzite was used, in addition to flint, quartz and other lithic raw materials, for making stone tools.
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