This type of rock is composed primarily of quartz and minerals that are found in clay. Shales can be broken easily into thin, parallel layers. Shale is ground up for use in making bricks and cement.
Sedimentary rock - pronounced sehd uh MEHN tuhr ee, is rock formed when mineral matter or remains of plants and animals settle out of water or, less commonly, out of air or ice. Sedimentary rock covers about three-fourths of the earth's land area and most of the ocean floor. In some places, such as at the mouth of the Mississippi River, sedimentary rocks are more than 40, feet 12, meters thick. Sedimentary rock is one of three major kinds of rock. The others are igneous rock Granite and metamorphic rock Marble.
There are many types of sedimentary rock and they have a variety of uses. The most common sedimentary rock is shale.
It is made of compressed mud--that is, a mixture of clay and silt fine particles of mineral matter. Shale is used in making bricks. Limestone, another common sedimentary rock, is made chiefly of the mineral calcite. Limestone is used for building, for making chalk, and for various other purposes. Cement is made of limestone with a little shale mixed in. Sandstone, made of sand, and conglomerate, composed of sand or gravel particles, are also commonly used for building. These enormous shale reservoirs hold enough natural gas to serve all of the United States' needs for twenty years or more.
Shale in brick and tile: Shale is used as a raw material for making many types of brick, tile, pipe, pottery, and other manufactured products. Brick and tile are some of the most extensively used and highly desired materials for building homes, walls, streets, and commercial structures. Everyone has contact with products made from shale. If you live in a brick house, drive on a brick road, live in a house with a tile roof, or keep plants in "terra cotta" pots, you have daily contact with items that were probably made from shale.
Many years ago these same items were made from natural clay. However, heavy use depleted most of the small clay deposits. Needing a new source of raw materials, manufacturers soon discovered that mixing finely ground shale with water would produce a clay that often had similar or superior properties.
Today, most items that were once produced from natural clay have been replaced by almost identical items made from clay manufactured by mixing finely ground shale with water.
The best way to learn about rocks is to have specimens available for testing and examination. Cement is another common material that is often made with shale. To make cement, crushed limestone and shale are heated to a temperature that is high enough to evaporate off all water and break down the limestone into calcium oxide and carbon dioxide.
The carbon dioxide is lost as an emission, but the calcium oxide combined with the heated shale makes a powder that will harden if mixed with water and allowed to dry. Cement is used to make concrete and many other products for the construction industry. Oil shale: A rock that contains a significant amount of organic material in the form of solid kerogen. This specimen is approximately four inches ten centimeters across.
Oil shale is a rock that contains significant amounts of organic material in the form of kerogen. This is usually much less efficient than drilling rocks that will yield oil or gas directly into a well. Extracting the hydrocarbons from oil shale produces emissions and waste products that cause significant environmental concerns.
This is one reason why the world's extensive oil shale deposits have not been aggressively utilized. Shale core samples: When shale is drilled for oil, natural gas, or mineral resource evaluation, a core is often recovered from the well.
The rock in the core can then be tested to learn about its potential and how the resource might be best developed. Shale is a rock composed mainly of clay-size mineral grains. These tiny grains are usually clay minerals such as illite, kaolinite, and smectite.
Shale usually contains other clay-size mineral particles such as quartz , chert , and feldspar. Other constituents might include organic particles, carbonate minerals, iron oxide minerals, sulfide minerals, and heavy mineral grains.
These "other constituents" in the rock are often determined by the shale's environment of deposition, and they often determine the color of the rock. Black shale: Organic-rich black shale.
Natural gas and oil are sometimes trapped in the tiny pore spaces of this type of shale. Like most rocks, the color of shale is often determined by the presence of specific materials in minor amounts.
Just a few percent of organic materials or iron can significantly alter the color of a rock. Shale gas plays: Since the late s, dozens of previously unproductive black organic shales have been successfully developed into valuable gas fields. See the article: " What is Shale Gas? A black color in sedimentary rocks almost always indicates the presence of organic materials. Just one or two percent organic materials can impart a dark gray or black color to the rock.
In addition, this black color almost always implies that the shale formed from sediment deposited in an oxygen-deficient environment. Any oxygen that entered the environment quickly reacted with the decaying organic debris. If a large amount of oxygen was present, the organic debris would all have decayed.
An oxygen-poor environment also provides the proper conditions for the formation of sulfide minerals such as pyrite , another important mineral found in most black shales. The presence of organic debris in black shales makes them the candidates for oil and gas generation.
If the organic material is preserved and properly heated after burial, oil and natural gas might be produced. The Barnett Shale, Marcellus Shale , Haynesville Shale , Fayetteville Shale , and other gas-producing rocks are all dark gray or black shales that yield natural gas.
Gray shales sometimes contain a small amount of organic matter. However, gray shales can also be rocks that contain calcareous materials or simply clay minerals that result in a gray color. Utica and Marcellus Shale: Two black organic shales in the Appalachian Basin are thought to contain enough natural gas to supply the United States for several years. These are the Marcellus Shale and Utica Shale. Shales that are deposited in oxygen-rich environments often contain tiny particles of iron oxide or iron hydroxide minerals such as hematite , goethite, or limonite.
Just a few percent of these minerals distributed through the rock can produce the red, brown, or yellow colors exhibited by many types of shale. The presence of hematite can produce a red shale. The presence of limonite or goethite can produce a yellow or brown shale. Pore spaces in shale are extremely tiny, and because of this gas cannot easily move out of the shale.
However, some gas can be released through hydraulic fracturing , a method where water and chemicals are pumped down a well under pressure to fracture the shale. In addition, horizontal drilling was found to help with the release of natural gas trapped in shale. Oil shale is rock that contains large amounts of kerogen. This type of shale forms when kerogen is buried at a depth of kilometers and can yield both liquid and gaseous hydrocarbons if the rock is heated or treated with solvents.
Because of this the extensive oil shale deposits around the world are not actively used. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change.
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