Quartzite is a hard metamorphic rock

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 which was originally sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

. Sandstone is converted into quartzite through heating and pressure usually related to tectonic

Tectonics

Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...

 compression within orogenic belts

Orogeny

Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...

. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe₂O₃). Other colors, such as yellow and orange, are due to other mineral impurities.

When sandstone is metamorphosed to quartzite, the individual quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals. Most or all of the original texture and sedimentary structures of the sandstone are erased by the metamorphism

Metamorphism

Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...

. Minor amounts of former cementing materials, iron oxide, carbonate and clay, often migrate during recrystallization and metamorphosis. This causes streaks and lenses to form within the quartzite.

Orthoquartzite is a very pure quartz sandstone composed of usually well rounded quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of 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

Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...

, rutile

Rutile

Rutile is a mineral composed primarily of titanium dioxide, TiO2.Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:...

 and magnetite

Magnetite

Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...

. Although few fossils are normally present, the original texture and sedimentary structures are preserved. The term is often misused, and should be used for only tightly-cemented metamorphic quartzites, not quartz-cemented quartz arenites. The typical distinction between the two (since each is a gradation into the other) is a proper quartzite is so highly cemented, diagentically altered, and metamorphosed that it will fracture and break across grain boundaries, not around them.
Quartzite is very resistant to chemical weathering

Weathering

Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...

 and often forms ridges and resistant hilltops. The nearly pure silica content of the rock provides little to form soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 from and therefore the quartzite ridges are often bare or covered only with a very thin layer of soil and little vegetation.

Uses

Because of its hardness and angular shape, crushed quartzite is often used as railway ballast

Track ballast

Track ballast forms the trackbed upon which railway sleepers or railroad ties are laid. It is packed between, below, and around the ties. It is used to facilitate drainage of water, to distribute the load from the railroad ties, and also to keep down vegetation that might interfere with the track...

.
Quartzite is a decorative stone and may be used to cover walls, as roofing tiles, as flooring, and stair steps. Crushed quartzite is sometimes used in road construction. High purity quartzite is used to produce ferrosilicon

Ferrosilicon

Ferrosilicon, or ferrosilicium, is a ferroalloy, an alloy of iron and silicon with between 15% and 90% silicon. It contains a high proportion of iron silicides. Its melting point is about 1200 °C to 1250 °C with a boiling point of 2355 °C...

, industrial silica sand, silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 and silicon carbide

Silicon carbide

Silicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...

.
During the Stone Age

Stone Age

The Stone Age is a broad prehistoric period, lasting about 2.5 million years , during which humans and their predecessor species in the genus Homo, as well as the earlier partly contemporary genera Australopithecus and Paranthropus, widely used exclusively stone as their hard material in the...

 quartzite was used as an (although inferior) alternative to flint

Flint

Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white, or brown in colour, and...

.

Occurrences

In the United States, formations of quartzite can be found in some parts of Pennsylvania, eastern South Dakota

South Dakota

South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...

, Central Texas, southwest Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

, Devil's Lake State Park in the Baraboo Hills in Wisconsin

Wisconsin

Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...

, the Wasatch Range

Wasatch Range

The Wasatch Range is a mountain range that stretches approximately from the Utah-Idaho border, south through central Utah in the western United States. It is generally considered the western edge of the greater Rocky Mountains, and the eastern edge of the Great Basin region...

 in Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, near Salt Lake City, Utah and as resistant ridges in the Appalachians and other mountain regions. Quartzite is also found in the Morenci Copper Mine in Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

. The town of Quartzsite

Quartzsite, Arizona

Quartzsite is a town in La Paz County, Arizona, United States. According to Census Bureau estimates, the population of the town was 3,397 in 2006.Interstate 10 runs directly through Quartzsite. It is at the intersection of U.S...

 in western Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

 derives its name from the quartzites in the nearby mountains

Maria Fold and Thrust Belt

The Maria fold and thrust belt is a portion of the North American Cordillera orogen in which geological structures accommodate roughly north-south to northwest-southeast vergent Mesozoic age crustal shortening. This lies in contrast to the remainder of the Cordillera, in which shortening is...

 in both Arizona and Southeastern California. A glassy vitreous quartzite has been described from the Belt Supergroup

Belt Supergroup

The Belt Supergroup, is an assemblage of Mesoproterozoic sedimentary rocks which outcrop chiefly in western Montana, but also exposed in Idaho, Washington, Wyoming, and British Columbia. It is most famous as the formation that makes up Glacier National Park in northwest Montana...

 in the Coeur d’Alene district of northern Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

.

In the United Kingdom, a craggy ridge of quartzite called the Stiperstones

Stiperstones

The Stiperstones is a very distinctive hill in the county of Shropshire, England. It is a quartzite ridge formed some 480 Million years ago. During the last Ice Age the summit stood out above the glaciers and was subject to constant freezing and thawing which shattered the quartzite into a mass of...

 (early Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 – Arenig Epoch

Arenig

In geology, the Arenigian refers both to a time interval during the Lower Ordovician period and also to the suite of rocks which were deposited during this interval.-History:...

, 500 Ma) runs parallel with the Pontesford-Linley fault, 6 km north-west of the Long Mynd

Long Mynd

The Long Mynd in Shropshire, England, is a part of the Shropshire Hills Area of Outstanding Natural Beauty. It is south of the county town Shrewsbury, and has an area of over 22 square kilometres , most of which takes the form of a heathland plateau. Most of the land on the Long Mynd is owned by...

 in south Shropshire

Shropshire

Shropshire is a county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. It borders Wales to the west...

. Also to be found in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 are the Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 "Wrekin quartizite" (in Shropshire), and the Cambrian "Hartshill

Hartshill

Hartshill is a village in the borough of North Warwickshire, England.Hartshill is three miles from Nuneaton town centre but is still regarded as a suburb of the town despite being in the North Warwickshire borough....

 quartzite" (Nuneaton

Nuneaton

Nuneaton is the largest town in the Borough of Nuneaton and Bedworth and in the English county of Warwickshire.Nuneaton is most famous for its associations with the 19th century author George Eliot, who was born on a farm on the Arbury Estate just outside Nuneaton in 1819 and lived in the town for...

 area). In Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

, Holyhead mountain

Holyhead Mountain

Holyhead Mountain is the highest hill on Holy Island, Anglesey, and the highest in the county of Anglesey, north Wales. It lies about three kilometres west of the town of Holyhead, and slopes steeply down to the Irish Sea on two sides...

 and most of Holy island

Holy Island, Anglesey

Holy Island Cybi') is an island on the western side of the larger Isle of Anglesey, North Wales, from which it is separated by a narrow, winding channel. It is called "Holy" because of the high concentration of standing stones, burial chambers and other religious sites on the small island. The...

 off Anglesey

Anglesey

Anglesey , also known by its Welsh name Ynys Môn , is an island and, as Isle of Anglesey, a county off the north west coast of Wales...

 sport excellent Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

 quartzite crags and cliffs. In the Scottish Highlands

Scottish Highlands

The Highlands is an historic region of Scotland. The area is sometimes referred to as the "Scottish Highlands". It was culturally distinguishable from the Lowlands from the later Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands...

, several mountains (e.g. Foinaven

Foinaven

Foinaven is a mountain in Scotland, situated in the far north-west corner of the Scottish Highlands. Like many of the monolithic mountains that surround it, the mountain is within the Moine Thrust Belt and is made up of imbricated layers of Cambrian quartzite which overlie the older Lewisian...

, Arkle

Arkle

Arkle was a famous Irish Thoroughbred racehorse. A bay gelding by Archive out of Bright Cherry, his grandsire was the unbeaten flat racehorse and prepotent sire Nearco. Arkle was bred at Ballymacoll Stud, County Meath by Mrs. Mary Alison Baker of Malahow House, near Naul, County Dublin...

) composed of Cambrian quartzite can be found in the far north-west Moine Thrust Belt

Moine Thrust Belt

The Moine Thrust Belt is a linear geological feature in the Scottish Highlands which runs from Loch Eriboll on the north coast 190 km south-west to the Sleat peninsula on the Isle of Skye...

 running in a narrow band from Loch Eriboll

Loch Eriboll

Loch Eriboll is a long sea loch on the north coast of Scotland, which has been used for centuries as a deep water anchorage as it is safe from the often stormy seas of Cape Wrath and the Pentland Firth...

 in a south-westerly direction to Skye

Skye

Skye or the Isle of Skye is the largest and most northerly island in the Inner Hebrides of Scotland. The island's peninsulas radiate out from a mountainous centre dominated by the Cuillin hills...

.

In Canada, the La Cloche Mountains

La Cloche Mountains

The La Cloche Mountains, also called the La Cloche Range, are a range of hills in Northern Ontario, along the northern shore of Lake Huron near Manitoulin Island. The hills are located in the Canadian Shield, and are composed primarily of white quartzite.They extend roughly from La Cloche...

 in Ontario

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

are composed primarily of white quartzite.

External links

• R. V. Dietrich's GemRocks: Quartzite
• CSU Pomona Geology: Quartzite
• Cowen's "The First Geologists" (chapter on Stone Age/Homo habilis use of quartzite)
• Minnesota Department of Natural Resources : Natural History: Minnesota's geology
• Wisconsin's Baraboo Syncline (map and aerial photos of Baraboo quartzite quarries)
• South Dakota 2002 Mineral Summary: Production, Exploration and Environmental Issues (including 2002 quartzite production)
• Big Sioux River: History of Sioux Falls and Quartzite Photos