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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A sedimentary rock formed by the consolidation and compaction of sand and held together by a natural cement, such as silica.
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.
A sedimentary rock composed of compacted and cemented sand. The sand grains are chiefly quartz and feldspar.
For more information on sandstone, visit Britannica.com.
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.
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.
Sandstone is a sedimentary rock composed mainly of sand-size mineral 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. Because of the hardness of the individual grains, uniformity of grain size and friability of its structure, sandstone is an excellent material 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 are porous enough to store large quantities, making them valuable aquifers. 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 limestones or other rocks fractured by seismic activity.
Sandstones are clastic in origin (as opposed to organic, like chalk and coal, or chemical, like gypsum and jasper). 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 in the range of 0.1 mm to 2 mm (rocks with smaller grain sizes include siltstones and shales and are typically called argillaceous sediments, as too are clays and rocks with larger grain sizes include both breccias and conglomerates and are termed rudaceous sediments).
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 sand dune region). 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 (terra cotta), 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. Deposition from sand dunes can be recognized by irregular and fluidly shaped weathering patterns and wavy coloration lines when sectioned, while water deposition will form more regular blocks when weathered. 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:
Once the geological characteristics of a sandstone have been established, it can then be assigned to one of three broad groups:
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.
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Sandstone with iron oxide bands |
Sandstone patterns on an chamber wall in Petra |
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Arbroath Abbey, showing distinctive sandstone colouring |
Arches National Park Sandstone landscape |
Parus Rock in Russia. |
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fossil shels in sandstone |
Sandstone-based building architecture, Hawa Mahal in Jaipur, India |
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Deutsch (German)
n. - Sandstein
Ελληνική (Greek)
n. - αμμόλιθος, αμμόπετρα
Português (Portuguese)
n. - grés (m) (Miner.)
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
العربيه (Arabic)
(الاسم) ألحجر ألرملي
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