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Dar Al Gani
The Dar al Gani (also known as DaG) is a meteorite field in the Libyan Sahara. The site is a plateau of limestone, about long and at its widest. Dark-colored meteorites can be easily spotted in this field, where they have also been well preserved due to the arid climate, and favorable geology consisting of basic rocks (clays, dolomites, and limestones) and lacking erosive quartz sand. As of July 2001, 869 meteorites with a total weight of were retrieved from the site; the largest weighed . The name ''Dar al Gani'' was given by the nomenclature committee of the Meteoritical Society. It does not exist in the National Atlas of Libya. However, the name ''Dur al Ghani'' was given to part of the Sarir al Qattusah plateau in the geological map of Libya. See also * Glossary of meteoritics This is a glossary of terms used in meteoritics, the science of meteorites. # * 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites. * 4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a Meteoroid#Fireball, fireball, also known as a shooting star; astronomers call the brightest examples "Bolide#Astronomy, bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and Impact event, impact the Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libya
Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to Egypt–Libya border, the east, Sudan to Libya–Sudan border, the southeast, Chad to Chad–Libya border, the south, Niger to Libya–Niger border, the southwest, Algeria to Algeria–Libya border, the west, and Tunisia to Libya–Tunisia border, the northwest. Libya is made of three historical regions: Tripolitania, Fezzan, and Cyrenaica. With an area of almost 700,000 square miles (1.8 million km2), it is the fourth-largest country in Africa and the Arab world, and the List of countries and outlying territories by total area, 16th-largest in the world. Libya has the List of countries by proven oil reserves, 10th-largest proven oil reserves in the world. The largest city and capital, Tripoli, Libya, Tripoli, is located in western Libya and contains over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
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Plateau
In geology and physical geography, a plateau (; ; ), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides have deep hills or escarpments. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wide ones. Formation Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, Plate tectonics movements and erosion by water and glaciers. Volcanic Volcanic plateaus are produced by volcanic activity. The Columbia Plateau in the north-western United States is an example. They may be formed by upwelling of volcanic magma or extrusion of lava. The un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base (chemistry)
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their applica .... A base was therefore a metal hydroxide such as Sodium hydroxide, NaOH or Calcium hydroxide, Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolomite (rock)
Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite rock from limestone was Belsazar Hacquet in 1778. Most dolomite was formed as a magnesium replacement of limestone or of lime mud before lithification. The geological process of conversion of calcite to dolomite is known as dolomitization and any intermediate product is known as dolomitic limestone. The "dolomite problem" refers to the vast worldwide depositions of dolomite in the past geologic record in contrast to the limited amounts of dolomite formed in modern times. Recent research has revealed sulfate-reducing bacteria living in anoxic conditions precipitate dolomite which ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classified as gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. Quartz is the mineral defining the val ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand, for example, aragonite, which has mostly been created, over the past 500million years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Somewhat more rarely, sand may be composed of calciu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteoritical Society
The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of the origin and history of the Solar System. Members The membership of the society comprises over 1,000 scientists and amateur enthusiasts from over 52 countries who are interested in a wide range of planetary science topics. Members interests include meteorites, cosmic dust, asteroids and comets, natural satellites, planets, impact events, and the origins of the Solar System. Activities The Meteoritical Society is the organization that records all known meteorites in its '' Meteoritical Bulletin''. The Society also publishes one of the world's leading planetary science journals, ''Meteoritics & Planetary Science'', and is a cosponsor with the Geochemical Society of the renowned journal ''Geochimica et Cosmochimica Acta''. The Society presen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossary Of Meteoritics
This is a glossary of terms used in meteoritics, the science of meteorites. # * 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites. * 4 Vesta – second-largest asteroid in the asteroid belt and likely source of the HED meteorites. * 221 Eos – an asteroid from the asteroid belt and one of the likely parent bodies of the CO meteorites. * 289 Nenetta – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites. * 3103 Eger – an asteroid from the asteroid belt and one of the likely parent bodies of the aubrites. * 3819 Robinson – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites. * IA meteorite – an iron meteorite group now part of the IAB group/complex. * IAB meteorite – an iron meteorite and primitive achondrite of the IAB group/complex. * IB meteorite – an iron meteorite group now part of the IAB group/complex. * IC meteorite – an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strewn Field (meteorite)
The term strewn field indicates the area where meteorites from a single fall are dispersed. It is also often used for the area containing tektites produced by large meteorite impact.''Tektites in the geological record: showers of glass from the sky''. Gerald Joseph Home McCall. Geological Society of London, 2001page 10/ref> Formation There are two strewnfield formation mechanisms: # Mid-air fragmentation: when a large meteoroid enters the atmosphere it often fragments into many pieces before touching the ground due to thermal shock. This mid-air explosion disperses material over a large oval-shaped area. The long axis of this oval is along the flight path of the meteoroid. When multiple-explosions occur, the material can be found in several overlapping ovals. # Impact fragmentation: when there is almost no mid-air fragmentation the fragmentation can occur upon impact. In this case the strewnfield shape can be different, usually circular. (e.g. Canyon Diablo at Meteor Crater; Austra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
