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{{About|high-pressure physics of minerals|physical attributes of minerals like [[Cleavage (crystal)|cleavage]] |Mineralogy#physical mineralogy}}
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'''Mineral physics''' is the science of materials that compose the interior of planets, particularly the Earth. It overlaps with [[petrophysics]], which focuses on whole-rock properties. It provides information that allows interpretation of surface measurements of [[seismic wave]]s, [[gravity anomalies]], [[geomagnetic field]]s and [[magnetotellurics|electromagnetic]] fields in terms of properties in the deep interior of the Earth. This information can be used to provide insights into [[plate tectonics]], [[mantle convection]], the [[geodynamo]] and related phenomena.
 
Laboratory work in mineral physics require high pressure measurements. The most common tool is a [[diamond anvil]] cell, which uses diamonds to put a small sample under pressure that can approach the conditions in the Earth's interior.
 
== Creating high pressures ==
The pace of progress in mineral physics has been determined, to a large extent, by the technology for reproducing the high pressures and temperatures in the Earth's interior. The most common tools for achieving this have been:
 
===Shock compression===
Many of the pioneering studies in mineral physics involved explosions or projectiles that subjected a sample to a shock. For a brief time interval, the sample is under pressure as the shock wave passes through. Pressures as high as any in the Earth have been achieved by this method. However, the method has some disadvantages. The pressure is very non-uniform and is not [[adiabatic]], so the pressure wave heats the sample up in passing. The conditions of the experiment must be interpreted in terms of a set of pressure-density curves called the '''Hugoniot curves'''.<ref>{{cite journal
|last=Ahrens
|first=T. J.
|year=1980
|title=Dynamic compression of Earth materials
|journal=[[Science (journal)|Science]]
|volume=207
|pages=1035–1041
|bibcode = 1980Sci...207.1035A |doi = 10.1126/science.207.4435.1035
|issue=4435}}</ref>
 
===Multi-anvil press===
Multi-anvil presses involve an arrangement of anvils to concentrate pressure from a press onto a sample. Typically the apparatus uses an arrangement eight cube-shaped [[tungsten carbide]] anvils to compress a ceramic octahedron containing the sample and a ceramic or Re metal furnace. The anvils are typically placed in a large hydraulic press. The method was developed by Kawai and Endo in Japan.<ref>{{cite journal|last=Kawai|first=Naoto|title=The generation of ultrahigh hydrostatic pressures by a split sphere apparatus|journal=Review of Scientific Instruments|year=1970|volume=41|issue=8|pages=1178&ndash;1181|doi=10.1063/1.1684753|bibcode = 1970RScI...41.1178K }}</ref> Unlike shock compression, the pressure exerted is steady, and the sample can be heated using a furnace. Pressures of about 28 GPa (equivalent to depths of 840&nbsp;km),<ref>{{cite journal|last=Kubo|first=Atsushi|coauthors=Akaogi, Masaki|title=Post-garnet transitions in the system Mg4Si4O12–Mg3Al2Si3O12 up to 28 GPa: phase relations of garnet, ilmenite and perovskite|journal=Physics of the Earth and Planetary Interiors|year=2000|volume=121|issue=1-2|pages=85–102|doi=10.1016/S0031-9201(00)00162-X|bibcode = 2000PEPI..121...85K }}</ref> and temperatures above 2300°C,<ref>{{cite journal|last=Zhang|first=Jianzhong|coauthors=Liebermann, Robert C., Gasparik, Tibor, Herzberg, Claude T., Fei, Yingwei|title=Melting and subsolidus relations of silica at 9 to 14 GPa|journal=Journal of Geophysical Research|year=1993|volume=98|issue=B11|pages=19785–19793|doi=10.1029/93JB02218|bibcode = 1993JGR....9819785Z }}</ref> can be attained using WC anvils and a lanthanum chromite furnace. The apparatus is very bulky and cannot achieve pressures like those in the diamond anvil cell (below), but it can handle much larger samples that can be quenched and examined after the experiment.<ref>{{cite web
  |title = Studying the Earth's formation: The multi-anvil press at work
  |url = https://www.llnl.gov/str/Minarik.html
  |publisher= [[Lawrence Livermore National Laboratory]]
  |accessdate=29 September 2010
  |ref = {{harvid|LLNL|2010}}
}}</ref> Recently, [[sintering|sintered]] diamond anvils have been developed for this type of press that can reach pressures of 90 GPa (2700&nbsp;km depth).<ref>{{cite journal|last=Zhai|first=Shuangmeng|coauthors=Ito, Eiji|title=Recent advances of high-pressure generation in a multianvil apparatus using sintered diamond anvils|journal=Geoscience Frontiers|year=2011|volume=2|issue=1|pages=101–106|doi=10.1016/j.gsf.2010.09.005}}</ref>
 
===Diamond anvil cell===
[[Image:DiaAnvCell1.jpg|thumb|Schematics of the core of a diamond anvil cell. The diamond size is a few millimeters at most]]
The [[diamond anvil cell]] is a small table-top device for concentrating pressure. It can compress a small (sub-millimeter sized) piece of material to [[Orders of magnitude (pressure)|extreme pressure]]s, which can exceed 3,000,000 atmospheres (300 [[Pascal (unit)|gigapascals]]).<ref name=Hemley1998>{{Cite journal
|last = Hemley
|first = Russell J.
|last2 = Ashcroft
|first2 = Neil W.
|year = 1998
|title = The Revealing Role of Pressure in the Condensed Matter Sciences
|journal = [[Physics Today]]
|volume = 51
|pages = 26
|doi = 10.1063/1.882374
|bibcode = 1998PhT....51h..26H
|issue = 8 }}</ref> This is beyond the pressures at the center of the Earth. The concentration of pressure at the tip of the [[diamonds]] is possible because of their [[hardness]], while their [[transparency and translucency|transparency]] and high [[thermal conductivity]] allow a variety of probes can be used to examine the state of the sample. The sample can be heated to thousands of degrees.
 
== Properties of materials ==
 
=== Equations of state ===
To deduce the properties of minerals in the deep Earth, it is necessary to know how their [[density]] varies with [[pressure]] and [[temperature]]. Such a relation is called an [[equation of state]] (EOS). A simple example of an EOS that is predicted by the [[Debye model]] for harmonic lattice vibrations is the Mie-Grünheisen equation of state:<br />
:<math> \left(\frac{dP}{dT} \right) = \frac{\gamma_D}{V}C_V, </math>
where <math>C_V</math> is the [[heat capacity]] and <math>\gamma_D</math> is the Debye gamma. The latter is one of many Grünheisen parameters that play an important role in high-pressure physics. A more realistic EOS is the [[Birch–Murnaghan equation of state]].<ref name=Poirier>{{harvnb|Poirier|2000}}</ref>
 
=== Interpreting seismic velocities ===
Inversion of seismic data give profiles of seismic velocity as a function of depth. These must still be interpreted in terms of the properties of the minerals. A very useful heuristic was discovered by [[Francis Birch (geophysicist)|Francis Birch]]: plotting data for a large number of rocks, he found a linear relation of the [[compressional wave]] velocity <math>v_p</math> of rocks and minerals of a constant average [[atomic weight]] <math>\overline{M}</math> with density <math>\rho</math>:<ref name="JGR61">{{cite journal
|last=Birch
|first=F.
|author-link = Francis Birch (geophysicist)
|year=1961
|title=The velocity of compressional waves in rocks to 10 kilobars. Part 2
|journal=[[Journal of Geophysical Research]]
|volume=66 |pages=2199–2224
|doi=10.1029/JZ066i007p02199
|bibcode = 1961JGR....66.2199B
|issue=7 }}</ref><ref name="GJRAS61">{{cite journal
|last=Birch
|first=F.
|author-link = Francis Birch (geophysicist)
|year=1961
|title=Composition of the Earth's mantle
|journal=[[Geophysical Journal of the Royal Astronomical Society]]
|volume=4 |pages=295–311
|doi=10.1111/j.1365-246X.1961.tb06821.x
|bibcode = 1961GeoJI...4..295B }}</ref><br />
:<math> v_p = a \overline{M} + b \rho </math>.
This makes it possible to extrapolate known velocities for minerals at the surface to predict velocities deeper in the Earth.
 
=== Other physical properties ===
* [[Viscosity]]
* [[Creep (deformation)]]
* [[Melting]]
* [[Electrical conduction]] and other transport properties
 
== References ==
{{Reflist|2}}
 
== Further reading ==
{{Refbegin}}
*{{cite book
  |last = Poirier
  |first = Jean-Paul
  |title = Introduction to the Physics of the Earth's Interior
  |series = Cambridge Topics in Mineral Physics & Chemistry
  |publisher = [[Cambridge University Press]]
  |year = 2000
  |isbn = 0-521-66313-X
}}
{{Refend}}
 
== External links ==
*{{cite web|url=http://serc.carleton.edu/NAGTWorkshops/mineralogy/mineral_physics.html |title=Teaching Mineral Physics Across the Curriculum |work=On the cutting edge - professional development for geoscience faculty |accessdate=21 May 2012}}
 
{{Geophysics navbox}}
 
[[Category:Geology]]
[[Category:Geophysics]]
[[Category:Mineralogy]]

Latest revision as of 21:07, 4 June 2014

I'm Numbers (23) from Perpignan, France.
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I have a part time job in a college.

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