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Encyclopedia > Olivine
Olivine

General
Category Mineral
Chemical formula (Mg, Fe)2SiO4
Identification
Color Yellow to yellow-green
Crystal system Orthorhombic
Cleavage Poor
Fracture Conchoidal
Mohs Scale hardness 6.5-7
Luster Vitreous
Refractive index 1.64-1.70
Birefringence +0.036
Streak White
Specific gravity 3.2-4.3


The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. It is one of the most common minerals on Earth, and has also been identified on the Moon, Mars, and comet Wild 2. Image File history File linksMetadata Download high-resolution version (1190x1312, 317 KB) [edit] ファイルの概要 Peridot. ... Minerals are natural compounds formed through geological processes. ... This article does not cite its references or sources. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete symmetry group. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For fractures in geologic formations, see Rock fracture. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Minerals are natural compounds formed through geological processes. ... Peridot (pronounced pear-uh-dot or pear-uh-doe, IPA: /pɛɹɪdɑːt/ or Fr. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... Apparent magnitude: up to -12. ... Adjectives: Martian Atmosphere Surface pressure: 0. ...


The ratio of magnesium and iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember) and fayalite (Fe-endmember). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (e.g., Fo70Fa30). Forsterite has an unusually high melting temperature at atmospheric pressure, almost 1900°C, but the melting temperature of fayalite is much lower (about 1200°C). The melting temperature varies smoothly between the two endmembers, as do other properties. Fig. ... Forsterite (Mg2SiO4) is the magnesium rich end-member of the olivine solid-solution series. ... Fayalite (Fe2SiO4) is the iron rich end-member of the olivine solid-solution series. ...


Olivine gives its name to the group of minerals with a related structure (the olivine group) which includes tephroite (Mn2SiO4), monticellite (CaMgSiO4), and kirschsteinite (CaFeSiO4). Tephroite is a non-metalic mineral that is one of the unusual minerals found at the famous mines of Sterling Hill and Franklin, New Jersey, USA. It can also be found in England and Sweden. ... Monticellite and kirschsteinite are gray silicate minerals of the olivine group which composition CaMgSiO4 and CaFeSiO4, respectivly. ... Monticellite and kirschsteinite are gray silicate minerals of the olivine group which composition CaMgSiO4 and CaFeSiO4, respectivly. ...

Contents

Identification and paragenesis

Olivine basalt
Olivine basalt
Peridotite xenoliths in basalt--olivines are light green crystals. Location: San Carlos Indian Reservation, Gila Co., Arizona, USA.
Peridotite xenoliths in basalt--olivines are light green crystals. Location: San Carlos Indian Reservation, Gila Co., Arizona, USA.

Olivine is usually named for its typically olive-green color (thought to be a result of traces of nickel), though it may alter to a reddish color from the oxidation of iron. It has a conchoidal fracture and is rather brittle. The hardness of olivine is 6.5–7, its relative density is 3.27–3.37, and it has a vitreous luster. It is transparent to translucent. Commons:Image:OlivineUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Commons:Image:OlivineUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image:Peridot in basalt. ... Image:Peridot in basalt. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Atomic mass 58. ... Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. ... A material is brittle if it is subject to fracture when subjected to stress i. ... The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... Relative density is a dimensionless ratio of the densities of two materials. ... Vitreous refers to a material in a glassy state. ... For the file system called Lustre, see Lustre (file system) Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ...


Transparent olivine is sometimes used as a gemstone called peridot, the French word for olivine. It is also called chrysolite, from the Greek words for gold and stone. Some of the finest gem-quality olivine has been obtained from a body of mantle rocks on Zabargad island in the Red Sea. A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. ... Peridot (pronounced pear-uh-dot or pear-uh-doe, IPA: /pɛɹɪdɑːt/ or Fr. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... Earth cutaway from core to exosphere. ... Zabargad, otherwise known as St. ... Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ...


Olivine occurs in both mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks. Mg-rich olivine crystallizes from magma that is rich in magnesium and low in silica. That magma crystallizes to mafic rocks such as gabbro and basalt. Ultramafic rocks such as peridotite, and dunite can be residues left after extraction of magmas, and typically they are more enriched in olivine after extraction of partial melts. Olivine, or high pressure structural variants, constitute over 50% of the Earth's upper mantle, making it one of the Earth's most common minerals by volume. The metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite. In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... Ultramafic (or ultrabasic) rocks are igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... Gabbro specimen. ... Basalt Basalt (IPA: ) is a common gray to black volcanic rock. ... Ultramafic (or ultrabasic) rocks are igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). ... Peridotite xenolith from San Carlos, southwestern United States. ... Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse grained or phaneritic texture. ... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... Dolomite crystals from Touissite, Morocco Dolomite is the name of both a carbonate rock and a mineral consisting of calcium magnesium carbonate (formula: CaMg(CO3)2) found in crystals. ... This article does not cite its references or sources. ...


Fe-rich olivine is relatively much less common, but it occurs in igneous rocks in small amounts in rare granites and rhyolites, and extremely Fe-rich olivine can exist stably with quartz and tridymite. In contrast, Mg-rich olivine does not occur stably with silica minerals, as it would react with them to form orthopyroxene ((Mg,Fe)2Si2O6). Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Rhyolite This page is about a volcanic rock. ... Quartz is one of the most common minerals in the Earths continental crust. ... Tridymite Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ...


Mg-rich olivine has also been discovered in meteorites, on Mars, and on Earth's moon. Such meteorites include chondrites, collections of debris from the early solar system, and pallasites, mixes of iron-nickel and olivine. The spectral signature of olivine has been seen in the dust disks around young stars. The tails of comets (which formed from the dust disk around the young Sun) often have the spectral signature of olivine, and the presence of olivine has recently been verified in samples of a comet from the Stardust spacecraft. [1] Willamette Meteorite A meteorite is a natural object originating in outer space that survives an impact with the Earths surface without being destroyed. ... Apparent magnitude: up to -12. ... Chondrites are meteorites of the stony type, that have not been modified due to melting or differentiation of the parent body. ... A slice of the Brahin pallasite, clearly showing the large olivine crystals suspended in the metal matrix. ... The Sun is the star at the center of the Solar System. ... An artists rendering of Stardust (NASA image) The Stardust capsule with cometary and interstellar samples landed at the U.S. Air Force Utah Test and Training Range at 10:10 UTC (15 January 2006) in the Bonneville Salt Flats. ...


Crystal structure

Figure 1: The atomic scale structure of olivine looking along the a axis. Oxygen is shown in red, silicon in pink, and magnesium/iron in blue. A projection of the unit cell is shown by the black rectangle
Figure 1: The atomic scale structure of olivine looking along the a axis. Oxygen is shown in red, silicon in pink, and magnesium/iron in blue. A projection of the unit cell is shown by the black rectangle

Minerals in the olivine group crystallize in the orthorhombic system (space group Pbnm) with isolated silicate tetrahedra, meaning that olivine is a nesosilicate. In an alternative view, the atomic structure can be described as a hexagonal, close-packed array of oxygen ions with half of the octahedral sites occupied with magnesium or iron ions and one-eighths of the tetrahedral sites occupied by silicon ions. This figure shows the atomic scale structure of olivine looking along the a axis (Pbnm setting) with the the long b axis across the page and the short c axis up the page. ... This figure shows the atomic scale structure of olivine looking along the a axis (Pbnm setting) with the the long b axis across the page and the short c axis up the page. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... The space group of a crystal is a mathematical description of the symmetry inherent in the structure. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... “Multivalent” redirects here. ...


There are three distinct oxygen sites (marked O1, O2, and O3 in figure 1), two distinct metal sites (M1 and M2), and only one distinct silicon site. O1, O2, M2, and Si all lie on mirror planes, while M1 exists on an inversion center. O3 lies in a general position. In mathematics, a reflection (also spelt reflexion) is a map that transforms an object into its mirror image. ...


High pressure polymorphs

At the high temperatures and pressures found at depth within the Earth the olivine structure is no longer stable. Below depths of about 410 km olivine undergoes a phase transition to the sorosilicate, wadsleyite and, at about 520 km depth, wadsleyite transforms into ringwoodite, which has the spinel structure. These phase transitions lead to a discontinuous increase in the density of the Earth's mantle that can be observed by seismic methods. In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. ... Earth cutaway from core to exosphere. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...


The pressure at which these phase transitions occur depends on temperature and iron content (Deer et al. 1992). At 800°C the pure magnesium end member, forsterite, transforms to wadsleyite at 11.8 gigapascals (118 kbar) and to ringwoodite at pressures above 14 GPa (140 kbar). Increasing the iron content decreases the pressure of the phase transition and narrows the wadsleyite stability field. At about 0.8 mole fraction fayalite, olivine transforms directly to ringwoodite over the pressure range 10–11.5 GPa (100–115 kbar). Fayalite transforms to Fe2SiO4 spinel at pressures below 5 GPa (50 kbar). Increasing the temperature increases the pressure of these phase transitions. The gigapascal, symbol GPa is an SI unit of pressure. ... The mole fraction is one way of expressing the relative concentration of a given species. ...


Historical and mythical uses

According to Rebbenu Bachya, the word "tarshish" in the verse Exodus 28:20 means "chrysolite" and was the stone on the Ephod representing the tribe of Asher. Not to be confused with Bahya ibn Paquda. ... It has been suggested that Pharaoh of the Exodus be merged into this article or section. ... The ephod (pronounced either ē´fod or ef´od) was one of eight ritual garments worn by the Israelite and later the Jewish High Priest while serving in the Jewish Temple in Jerusalem. ... In the Book of Genesis, Asher (אָשֵׁר, Standard Hebrew Ašer, Tiberian Hebrew ʾĀšēr) is a son of Jacob and Zilpah, and the founder of the Tribe of Asher. ...


See also

Gem animals. ... Within the field of geology, Bowens reaction series is the work of the petrologist, Norman L. Bowen who was able to explain why certain types of minerals tend to be found together while others are almost never associated with one another. ...

Notes

  1. ^ Press Release 06-091. Jet Propulsion Laboratory Stardust website, retrieved May 30, 2006.

References

Wikimedia Commons has media related to:
Olivine
  • Klein, Cornelis; and C. S. Hurlburt (1985). Manual of Mineralogy (21rst ed.). New York: John Wiley & Sons, 681 pp. ISBN 0-471-80580-7. 
  • Deer, W. A.; R. A. Howie, and J. Zussman (1992). An Introduction to the Rock-Forming Minerals (2nd ed.). London: Longman, 696 pp. ISBN 0-582-30094-0. 

  Results from FactBites:
 
OLIVINE (Magnesium Iron Silicate) (869 words)
Olivine, however is not officially recognized as a mineral (see other non-minerals such as apophyllite, tourmaline, mica, serpentine, chlorite and apatite).
Olivine is found in ultramafic igneous rocks and marbles that formed from metamorphosed impure limestones.
Olivine can be altered to the mineral serpentine and this mineral is found in kimberlites, ophiolites and gabbros that started out with large amounts of olivine at one time.
Olivine - LoveToKnow 1911 (626 words)
Olivine is a common constituent of many basic and ultrabasic rocks, such as basalt, diabase, gabbro and peridotite: the dunite, of Dun Mountain near Nelson in New Zealand, is an almost pure olivine-rock.
Olivine is especially liable to alteration into serpentine (hydrated magnesium silicate); the alteration proceeds from the outside of the crystals and grains or along irregular cracks in their interior, and gives rise to the separation of iron oxides and an irregular net-work of fibrous serpentine, which in rock-sections presents a very characteristic appearance.
It occurs as nodules in a volcanic rock at Fayal in the Azores, and in granite - at the Mourne Mountains in Ireland; and as small crystals in cavities in rhyolite at the Yellowstone Park, U.S.A. It is a common constituent of crystalline iron slags.
  More results at FactBites »

 
 

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