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Bridgmanite
Silicate perovskite is either (the magnesium end-member is called bridgmanite) or (calcium silicate known as davemaoite) when arranged in a perovskite structure. Silicate perovskites are not stable at Earth's surface, and mainly exist in the lower part of Earth's mantle, between about depth. They are thought to form the main mineral phases, together with ferropericlase. Discovery The existence of silicate perovskite in the mantle was first suggested in 1962, and both and had been synthesized experimentally before 1975. By the late 1970s, it had been proposed that the seismic discontinuity at about 660 km in the mantle represented a change from spinel structure minerals with an olivine composition to silicate perovskite with ferropericlase. Natural silicate perovskite was discovered in the heavily shocked Tenham meteorite. In 2014, the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA) approved the na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Mantle (Earth)
The lower mantle, historically also known as the mesosphere, represents approximately 56% of Earth's total volume, and is the region from 660 to 2900 km below Earth's surface; between the transition zone and the outer core. The preliminary reference Earth model (PREM) separates the lower mantle into three sections, the uppermost (660–770 km), mid-lower mantle (770–2700 km), and the D layer (2700–2900 km). Pressure and temperature in the lower mantle range from 24–127 GPa and 1900–2600 K. It has been proposed that the composition of the lower mantle is pyrolitic, containing three major phases of bridgmanite, ferropericlase, and calcium-silicate perovskite. The high pressure in the lower mantle has been shown to induce a spin transition of iron-bearing bridgmanite and ferropericlase, which may affect both mantle plume dynamics and lower mantle chemistry. The upper boundary is defined by the sharp increase in seismic wave velocities and density at a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percy Williams Bridgman
Percy Williams Bridgman (April 21, 1882 – August 20, 1961) was an American physicist who received the 1946 Nobel Prize in Physics for his work on the physics of high pressures. He also wrote extensively on the scientific method and on other aspects of the philosophy of science. The Bridgman effect, the Bridgman–Stockbarger technique, and the high-pressure mineral bridgmanite are named after him. Biography Early life Bridgman was born in Cambridge, Massachusetts, and grew up in nearby Auburndale. Bridgman's parents were both born in New England. His father, Raymond Landon Bridgman, was "profoundly religious and idealistic" and worked as a newspaper reporter assigned to state politics. His mother, Mary Ann Maria Williams, was described as "more conventional, sprightly, and competitive". Bridgman attended both elementary and high school in Auburndale, where he excelled at competitions in the classroom, on the playground, and while playing chess. Described as both shy and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Zone (Earth)
The transition zone is part of the Earth's mantle, and is located between the lower mantle and the upper mantle, between a depth of 410 and 660 km (250 to 400 mi). The Earth's mantle, including the transition zone, consists primarily of peridotite, an ultramafic igneous rock. The mantle was divided into the upper mantle, transition zone, and lower mantle as a result of sudden seismic-velocity discontinuities at depths of 410 and 660 km (250 to 400 mi). This is thought to occur as a result of rearrangement of grains in olivine (which constitutes a large portion of peridotite) at a depth of 410 km, to form a denser crystal structure as a result of the increase in pressure with increasing depth. Below a depth of 660 km, evidence suggests due to pressure changes ringwoodite minerals change into two new denser phases, bridgmanite and periclase. This can be seen using body waves from earthquakes, which are converted, reflected or refracted at the boundar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perovskite (structure)
A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two positively charged ions (i.e. cations), often of very different sizes, and X is a negatively charged ion (an anion, frequently oxide) that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where either/both the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenham Meteorite
Tenham meteorites are the fragments of a larger meteorite that fell in 1879 in a remote area of Australia near the Tenham station, South Gregory, in western Queensland. Although the fall was seen by a number of people, its exact date has not been established. Bright meteors were seen to be moving roughly from west to east. Stones were subsequently recovered from over a large area, about long by wide. Because the Tenham meteorites were recovered quite soon after they fell, from a remote and dry region in which weathering and other alterations had not set in, they have been invaluable for scientific study of meteorites and their mineral contents. They are examples of chondritic meteorites, containing a high level of organic compounds, and rich in silicates, oxides, and sulfides. Many scientific studies have explored the mineralogy of these meteorites and their non-terrestrial features. Because the Tenham meteorites show evidence of high pressure deformations, they have been used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity tow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthorhombic Crystal System
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal. Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , row oC, column Primitive, where the cell parameters are given as a1 = a2, α = β = 90° it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. Note that the length a of the primiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enstatite
Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) – ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, , has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En80Fs20). Polymorphs and varieties Most natural crystals are orthorhombic (space group P''bca'') although three polymorphs are known. The high temperature, low pressure polymorphs are protoenstatite and protoferrosilite (also orthorhombic, space group P''bcn'') while the low temperature forms, clinoenstatite and clinoferrosilite, are monoclinic (space group P2''1/c''). Weathered enstatite with a small amount of iron takes on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mindat
Mindat may refer to: Places in Burma/Myanmar *Mindat, Chin State, in Burma *Mindat Township, in Burma *Mindat District in Chin State, Burma Other uses *Mindat Min Kanaung Mintha ( my, ကနောင်မင်းသား; 31 January 1820 – 2 August 1866) was crown prince of Burma and son of King Tharrawaddy and younger brother of King Mindon of Burma. Towards the end of the Second Anglo-Burmese Wa ..., a Burmese prince * Mindat.org, an online mineralogy database {{dab, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ringwoodite
Ringwoodite is a high-pressure phase of Mg2SiO4 (magnesium silicate) formed at high temperatures and pressures of the Earth's mantle between depth. It may also contain iron and hydrogen. It is polymorphous with the olivine phase forsterite (a magnesium iron silicate). Ringwoodite is notable for being able to contain hydroxide ions (oxygen and hydrogen atoms bound together) within its structure. In this case two hydroxide ions usually take the place of a magnesium ion and two oxide ions. Combined with evidence of its occurrence deep in the Earth's mantle, this suggests that there is from one to three times the world ocean's equivalent of water in the mantle transition zone from 410 to 660 km deep. This mineral was first identified in the Tenham meteorite in 1969, and is inferred to be present in large quantities in the Earth's mantle. Ringwoodite was named after the Australian earth scientist Ted Ringwood (1930–1993), who studied polymorphic phase transitions in the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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