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sandstone

 
Dictionary: sand·stone   (sănd'stōn') pronunciation
n.

A sedimentary rock formed by the consolidation and compaction of sand and held together by a natural cement, such as silica.


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Sci-Tech Encyclopedia: Sandstone
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A clastic sedimentary rock comprising an aggregate of sand-sized (0.06–2.0-mm) fragments of minerals, rocks, or fossils held together by a mineral cement. Sandstone forms when sand is buried under successive layers of sediment. During burial the sand is compacted, and a binding agent such as quartz, calcite, or iron oxide is precipitated from ground water which moves through passageways between grains. Sandstones grade upward in grain size into conglomerates and breccias; they grade downward in size into siltstones and shales. When the proportion of fossil fragments or carbonate grains is greater than 50%, sandstones grade into clastic limestones. See also Breccia; Conglomerate; Limestone; Sand; Shale.

The basic components of a sandstone are framework grains (sand particles), which supply the rock's strength; matrix or mud-sized particles, which fill some of the space between grains; and crystalline cement. The composition of the framework grains reveals much about the history of the derivation of the sand grains, including the parent rock type and weathering history of the parent rock. Textural attributes of sandstone are the same as those for sand, and they have the same genetic significance. See also Sand.

Sandstones are classified according to the relative proportion of quartz to other grain types, and according to the ratio of feldspar grains to finely crystalline lithic fragments. Quartz-rich sandstones are commonly called quartz-arenite. Sandstones poor in quartz are commonly called arkose, when feldspar grains are more abundant than lithic fragments, and litharenite (or graywacke) when the reverse is true. Subarkose and sublitharenite (or subgraywacke) refer to analogous sandstones of intermediate quartz content. Sandstones composed dominantly of calcareous grains are called calcarenite, and represent a special variety of limestone. Other sandstones composed exclusively of volcanic debris are called volcanic sandstone, and are gradational, through the interplay of eruptive and erosional processes, to tuff, the fragmental volcanic rocks produced by the disintegration of magma during explosive volcanic eruptions. See also Arenaceous rocks; Arkose; Feldspar; Graywacke; Quartz; Tuff.

Because sandstone can possess up to 35% connected pore space, it is the most important reservoir rock in the Earth's crust. In the future sandstone may serve as a reservoir into which hazardous fluids, such as nuclear wastes, are injected for storage. See also Hazardous waste.

Sandstone which is easily split (flagstone) and has an attractive color is used as a building stone. Sandstone is also an important source of sand for the glass industry and the construction industry, where it is used as a filler in cement and plaster. Crushed sandstone is used as road fill and railroad ballast. Silica-cemented sandstone is used as firebrick in industrial furnaces. Some of the most extensive deposits of uranium are found in sandstones deposited in ancient stream channels. See also Glass; Sedimentary rocks; Stone and stone products; Uranium.


Geography Dictionary: sandstone
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A sedimentary rock composed of compacted and cemented sand. The sand grains are chiefly quartz and feldspar.


Sedimentary rock formed from sand-sized grains (0.0025 – 0.08 in., or 0.06 – 2 mm, in diameter). The spaces between grains may be empty or filled with either a chemical cement of silica or calcium carbonate or a fine-grained matrix of silt and clay particles. The principal mineral constituents of the grain framework are quartz, feldspar, and rock fragments. Sandstones are quarried for use as building stone. Because of their abundance, diversity, and mineralogy, sandstones are also important to geologists as indicators of erosional and depositional processes. See also graywacke.

For more information on sandstone, visit Britannica.com.

Architecture: sandstone
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Sedimentary rock composed of sand-sized grains, naturally cemented by mineral materials. In most sandstone used for building, quartz grains predominate; often used for decorative elements in buildings because it is easy to carve.


 
Columbia Encyclopedia: sandstone
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sandstone, sedimentary rock formed by the cementing together of grains of sand. The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone varies according to the character of the cementing material; quartz sandstones cemented with quartz are the hardest. Sandstones are commonly gray, buff, red, or brown although green and some other colors are also found. Green sandstones often contain, in addition to sand and glauconite, fossil shells and iron oxides; those that break apart easily are known as greensands and are sometimes used to replenish depleted potash in soils. Sandstones are widely used in construction and industry. Varieties of sandstone include arkose, which contains feldspar and resembles granite, and graywacke, a gray or sometimes greenish or black rock composed of quartz and fledspar with numerous fragments of other rocks, such as shale, slate, quartzite, granite, and basalt. Sandstone may be crushed to the form of loose sand grains, which can then be put to the same industrial uses as sand. See brownstone.


Science Dictionary: sandstone
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A sedimentary rock formed of sand-sized grains that have been either compacted or cemented together. Altough sandstone usually consists primarily of quartz, it can also consist of other minerals.

Wikipedia: Sandstone
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Sandstone
 —  Sedimentary Rock  —
Sandstone Image
Prepared sample of sandstone
Composition
Typically quartz and/or feldspar (on earth); lithic fragments are also common. Other minerals may be found in particularly immature sandstone.

Sandstone (sometimes known as arenite) 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 color, but the most common colors are tan, brown, yellow, red, gray and white. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions.

Some sandstones are resistant to weathering, yet are easy to work. This makes sandstone a common building and paving material. However, some that have been used in the past, such as the Collyhurst sandstone used in North West England, have been found less resistant, necessitating repair and replacement in older buildings.[1] Because of the hardness of the individual grains, uniformity of grain size and friability of their structure, some types of sandstone are excellent materials from which to make grindstones, for sharpening blades and other implements. Non-friable sandstone can be used to make grindstones for grinding grain, e.g., gritstone.

Rock formations that are primarily sandstone usually allow percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are more apt to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity.

Contents

Origins

Sand from Coral Pink Sand Dunes State Park, Utah. These are grains of quartz with a hematite coating providing the orange color. Scale bar is 1.0 mm.
Millet-Seed sandstone macro (size: ~4 cm or ~1.6 in).

Sandstones are clastic in origin (as opposed to either organic, like chalk and coal, or chemical, like gypsum and jasper).[2] They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals. The cements binding these grains together are typically calcite, clays and silica. Grain sizes in sands are defined (in geology) within the range of 0.0625 mm to 2 mm (0.002-0.079 inches). Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are typically called argillaceous sediments; rocks with larger grain sizes, including breccias and conglomerates are termed rudaceous sediments.

Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth by erosion from flash flooding over millions of years.

The formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water (as in a river, lake, or sea) or from air (as in a desert). Typically, sedimentation occurs by the sand settling out from suspension; i.e., ceasing to be rolled or bounced along the bottom of a body of water (e.g., seas or rivers) or ground surface (e.g., in a desert or erg). Finally, once it has accumulated, the sand becomes sandstone when it is compacted by pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains.

The most common cementing materials are silica and calcium carbonate, which are often derived either from dissolution or from alteration of the sand after it was buried. Colors will usually be tan or yellow (from a blend of the clear quartz with the dark amber feldspar content of the sand). A predominant additional colorant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red (terracotta), with additional manganese imparting a purplish hue. Red sandstones are also seen in the Southwest and West of England and Wales, as well as central Europe and Mongolia. The regularity of the latter favors use as a source for masonry, either as a primary building material or as a facing stone, over other construction.

The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size, sorting and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings:

  • Terrestrial environments
Sandstone near Stadtroda, Germany.
  1. Rivers (levees, point bars, channel sands)
  2. Alluvial fans
  3. Glacial outwash
  4. Lakes
  5. Deserts (sand dunes and ergs)
  • Marine environments
  1. Deltas
  2. Beach and shoreface sands
  3. Tidal flats
  4. Offshore bars and sand waves
  5. Storm deposits (tempestites)
  6. Turbidites (submarine channels and fans)

Types

Sandstone composed mainly of quartz grains

Sandstones fall into several major groups based on their mineralogy and texture. Below is a partial list of common sandstone types.

  • quartz arenites are made up almost entirely of quartz grains, usually well sorted and rounded. These pure quartz sands result from extensive weathering that occurred before and during transport and removed everything but quartz, the most stable mineral. They are common in beach environments.
  • arkoses are more than 25 percent feldspar.[2] The grains tend to be poorly rounded and less well sorted than those of pure quartz sandstones. These feldspar-rich sandstones come from rapidly eroding granitic and metamorphic terrains where chemical weathering is subordinate to physical weathering.
  • lithic sandstones contain many lithic fragments derived from fine-grained rocks, mostly shales, volcanic rocks, and fine-grained metamorphic rocks.
  • graywacke is a heterogeneous mixture of lithic fragments and angular grains of quartz and feldspar, and/or grains surrounded by a fine-grained clay matrix. Much of this matrix is formed by relatively soft fragments, such as shale and some volcanic rocks, that are chemically altered and physically compacted after deep burial of the sandstone formation.
  • Eolianite is a term used for a rock which is composed of sand grains that show signs of significant transportation by wind. These have usually been deposited in desert environments. They are commonly extremely well sorted and rich in quartz.
  • Oolite is more a limestone than a sandstone, but is made sand-sized carbonate ooids, and is common in saline beaches with gentle wave action.

Sandstone composition is (generally) based on the make up of the framework, or sand-sized grains in the sandstone. This is typically done by point-counting a thin section of the sandstone using a method like the Gazzi-Dickinson Method. The composition of a sandstone can have important information regarding the genesis of the sediment when used with QFL diagrams.


According to the USGS, U.S. sandstone production in 2005 was 192,000 metric tons worth $24.3 million, the largest component of which was the 121,000 metric tons worth $9.75 million of flagstone or dimension stone.[3]

Gallery

See also

Notes

  1. ^ Edensor, T. & Drew, I. Building stone in the City of Manchester: St Ann's Church
  2. ^ a b "A Basic Sedimentary Rock Classification", L.S. Fichter, Department of Geology/Environmental Science, James Madison University (JMU), Harrisonburg, Virginia, October 2000, webpage: JMU-sed-classif (accessed: March 2009): separates clastic, chemical & biochemical (organic).
  3. ^ USGS 2005 Minerals Yearbook (see below: References).

References

  • Boggs, J.R., 2000, Principles of sedimentology and stratigraphy, 3rd ed. Toronto: Merril Publishing Company. ISBN 0-13-099696-3.
  • Folk, R.L., 1965, Petrology of sedimentary rocks PDF version. Austin: Hemphill’s Bookstore. 2nd ed. 1981, ISBN 0-914696-14-9.
  • Pettijohn, F.J., P.E. Potter and R. Siever, 1987, Sand and sandstone, 2nd ed. Springer-Verlag. ISBN 0-387-96350-2.
  • Scholle, P.A., 1978, A Color illustrated guide to constituents, textures, cements, and porosities of sandstones and associated rocks, American Association of Petroleum Geologists Memoir no. 28. ISBN 0-89181-304-7.
  • Scholle, P.A., and D. Spearing, 1982, Sandstone depositional environments: clastic terrigenous sediments , American Association of Petroleum Geologists Memoir no. 31. ISBN 0-89181-307-1.
  • USGS Minerals Yearbook: Stone, Dimension, Thomas P. Dolley, U.S. Dept. of the Interior, 2005 (format: PDF).

Translations: Sandstone
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Dansk (Danish)
n. - sandsten

Nederlands (Dutch)
zandsteen

Français (French)
n. - grès

Deutsch (German)
n. - Sandstein

Ελληνική (Greek)
n. - αμμόλιθος, αμμόπετρα

Italiano (Italian)
arenaria

Português (Portuguese)
n. - grés (m) (Miner.)

Русский (Russian)
песчаник

Español (Spanish)
n. - arenisca

Svenska (Swedish)
n. - sandsten

中文(简体)(Chinese (Simplified))
沙岩

中文(繁體)(Chinese (Traditional))
n. - 沙岩

한국어 (Korean)
n. - 사암

日本語 (Japanese)
n. - 砂岩

العربيه (Arabic)
‏(الاسم) ألحجر ألرملي‏

עברית (Hebrew)
n. - ‮אבן-חול‬


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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
Geography Dictionary. A Dictionary of Geography. Copyright © Susan Mayhew 1992, 1997, 2004. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Architecture. McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/ Read more
Science Dictionary. The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved.  Read more
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