All about Quartzite Rocks
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All about Quartzite rocksWhat is
All about Quartzite rocks
What is Quartzite?
Metamorphism recrystallizes the sand grains and the silica cement that binds them together. The result is a network of interlocking quartz grains of incredible strength.
Physical Properties of Quartzite
The interlocking crystalline structure of quartzite makes it a hard, tough, durable rock. It is so tough that it breaks through the quartz grains rather than breaking along the boundaries between them. This is a characteristic that separates true quartzite from sandstone
Quartzite is usually white to gray in color. Some rock units that are stained by iron can be pink, red, or purple. Other impurities can cause quartzite to be yellow, orange, brown, green, or blue.
The quartz content of quartzite gives it a hardness of about seven on the Mohs Hardness Scale. Its extreme toughness made it a favorite rock for use as an impact tool by early people.
What is Mohs Hardness Scale?
Its conchoidal fracture allowed it to be shaped into large cutting tools such as ax heads and scrapers. Its coarse texture made it less suitable for producing tools with fine edges such as knife blades and projectile points.
Where Does Quartzite Form?
Most quartzite forms during mountain-building events at convergent plate boundaries where sandstone was deposited on a continental plate. There, the sandstone is metamorphosed into quartzite by the intense pressure of a plate collision and often by deep burial.
Compressional forces at the plate boundary fold and fault the rocks and thicken the crust into a mountain range. Quartzite is an important rock type in folded mountain ranges throughout the world.
Quartzite as a Ridge-Former
Quartzite is also a poor soil-former. Unlike feldspars which break down to form clay minerals, the weathering debris of quartzite is quartz. It is therefore not a rock type that contributes well to soil formation. For that reason it is often found as exposed bedrock with little or no soil cover.
Uses of Quartzite
Quartzite has a diversity of uses in construction, manufacturing, architecture, and decorative arts. Although its properties are superior to many currently used materials, its consumption has always been low for various reasons.
Architectural Use. In architecture, marble and granite have been the favorite materials for thousands of years. Quartzite, with a Mohs hardness of seven along with greater toughness, is superior to both in many uses. It stands up better to abrasion in stair treads, floor tiles, and countertops. It is more resistant to most chemicals and environmental conditions. It is available in a range of neutral colors that many people enjoy. The use of quartzite in these uses is growing slowly as more people learn about it.
Construction Use
Unfortunately, the same durability that makes quartzite a superior construction material also limits its use. Its hardness and toughness cause heavy wear on crushers, screens, truck beds, cutting tools, loaders, tires, tracks, drill bits, and other equipment. As a result, the use of quartzite is mainly limited to geographic areas where other aggregates are not available.
Decorative and Gemological Use
Quartzite can be a very attractive stone when it is colored by inclusions. Inclusions of fuchsite (a green chromium-rich variety of muscovite mica) can give quartzite a pleasing green color. If the quartzite is semitransparent to translucent, the flat flakes of mica can reflect light to produce a glittering luster known as aventurescence.
Material that displays this property is known as "aventurine," a popular material used to produce beads, cabochons, tumbled stones, and small ornaments. Aventurine can be pink or red when stained with iron. Included dumortierite produces a blue color. Other inclusions produce white, gray, orange, or yellow aventurine.
Stone Tools
Quartzite has been used by humans to make stone tools for over one million years. It was mainly used for impact tools, but its conchoidal fracture allowed it to be broken to form sharp edges. Broken pieces of quartzite were used for crude cutting and chopping tools.
Quartzite was not the preferred material for producing cutting tools such as knife blades and projectile points - but it has been used. Flint, chert, jasper, agate, and obsidian all can be knapped to produce fine cutting edges, which are difficult to produce when working quartzite. Quartzite was most frequently used when it was locally abundant and superior materials were rare or not available.
#quartzite
What is Quartzite?
Metamorphism recrystallizes the sand grains and the silica cement that binds them together. The result is a network of interlocking quartz grains of incredible strength.
Physical Properties of Quartzite
The interlocking crystalline structure of quartzite makes it a hard, tough, durable rock. It is so tough that it breaks through the quartz grains rather than breaking along the boundaries between them. This is a characteristic that separates true quartzite from sandstone
Quartzite is usually white to gray in color. Some rock units that are stained by iron can be pink, red, or purple. Other impurities can cause quartzite to be yellow, orange, brown, green, or blue.
The quartz content of quartzite gives it a hardness of about seven on the Mohs Hardness Scale. Its extreme toughness made it a favorite rock for use as an impact tool by early people.
What is Mohs Hardness Scale?
Its conchoidal fracture allowed it to be shaped into large cutting tools such as ax heads and scrapers. Its coarse texture made it less suitable for producing tools with fine edges such as knife blades and projectile points.
Where Does Quartzite Form?
Most quartzite forms during mountain-building events at convergent plate boundaries where sandstone was deposited on a continental plate. There, the sandstone is metamorphosed into quartzite by the intense pressure of a plate collision and often by deep burial.
Compressional forces at the plate boundary fold and fault the rocks and thicken the crust into a mountain range. Quartzite is an important rock type in folded mountain ranges throughout the world.
Quartzite as a Ridge-Former
Quartzite is also a poor soil-former. Unlike feldspars which break down to form clay minerals, the weathering debris of quartzite is quartz. It is therefore not a rock type that contributes well to soil formation. For that reason it is often found as exposed bedrock with little or no soil cover.
Uses of Quartzite
Quartzite has a diversity of uses in construction, manufacturing, architecture, and decorative arts. Although its properties are superior to many currently used materials, its consumption has always been low for various reasons.
Architectural Use. In architecture, marble and granite have been the favorite materials for thousands of years. Quartzite, with a Mohs hardness of seven along with greater toughness, is superior to both in many uses. It stands up better to abrasion in stair treads, floor tiles, and countertops. It is more resistant to most chemicals and environmental conditions. It is available in a range of neutral colors that many people enjoy. The use of quartzite in these uses is growing slowly as more people learn about it.
Construction Use
Unfortunately, the same durability that makes quartzite a superior construction material also limits its use. Its hardness and toughness cause heavy wear on crushers, screens, truck beds, cutting tools, loaders, tires, tracks, drill bits, and other equipment. As a result, the use of quartzite is mainly limited to geographic areas where other aggregates are not available.
Decorative and Gemological Use
Quartzite can be a very attractive stone when it is colored by inclusions. Inclusions of fuchsite (a green chromium-rich variety of muscovite mica) can give quartzite a pleasing green color. If the quartzite is semitransparent to translucent, the flat flakes of mica can reflect light to produce a glittering luster known as aventurescence.
Material that displays this property is known as "aventurine," a popular material used to produce beads, cabochons, tumbled stones, and small ornaments. Aventurine can be pink or red when stained with iron. Included dumortierite produces a blue color. Other inclusions produce white, gray, orange, or yellow aventurine.
Stone Tools
Quartzite has been used by humans to make stone tools for over one million years. It was mainly used for impact tools, but its conchoidal fracture allowed it to be broken to form sharp edges. Broken pieces of quartzite were used for crude cutting and chopping tools.
Quartzite was not the preferred material for producing cutting tools such as knife blades and projectile points - but it has been used. Flint, chert, jasper, agate, and obsidian all can be knapped to produce fine cutting edges, which are difficult to produce when working quartzite. Quartzite was most frequently used when it was locally abundant and superior materials were rare or not available.
#quartzite
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