FACTOID # 3: South Carolina has the highest rate of violent crimes and aggravated assaults per capita among US states.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Xenocryst
A xenolith
A xenolith

A xenolith (Greek: "foreign rock") is a rock fragment which becomes enveloped in a larger rock during the latter's development and hardening. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement and eruption. Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme, or picked up along the base of a flowing lava on Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica deficient lava and diamonds within kimberlite diatremes. A xenolith (public domain from [1]) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... A xenolith (public domain from [1]) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ... The Blue Marble: The famous photo of the Earth taken en route to the Moon by Apollo 17s Harrison Schmitt on December 7, 1972. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when molten 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. ... Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... A Diatreme is a volcanic pipe or feature formed by a gas or volatile rich explosive magma. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... // For other uses, including the shape â—Š, see Diamond (disambiguation). ... Hewn kimberlite core sample from the James Bay Lowlands region of Northern Ontario, Canada. ...


Although xenolith is most commonly associated with igneous inclusions, a broad definition could include rock fragments which have become encased in sedimentary rock. Xenoliths are sometimes found in recovered meteorites. Two types of sedimentary rock: limey shale overlaid by limestone. ... A meteorite is an extraterrestrial body that survives its impact with the Earths surface without being destroyed. ...

A xenolith in Larchmont, New York
Enlarge
A xenolith in Larchmont, New York

To be considered a true xenolith, the included rock must be identifiably different from the rock in which it is enveloped; an included rock of similar type is called an autolith.


Xenoliths and xenocrysts provide important information about the composition of the otherwise innacessible mantle. Basalts, kimberlites, lamproites and lamprophyres which have their source in the upper mantle often contain fragments and crystals assumed to be a part of the originating mantle mineralogy. Xenoliths of dunite, peridotite and spinel lherzolite in basaltic lava flows are one example. Kimberlites contain, in addition to diamond xenocrysts, fragments of lherzolites of varying composition. The aluminium bearing minerals of these fragments provide clues to the depth of origin. Calcic plagioclase is stable to 25 km depth. Between 25 km and about 60 km, spinel is the stable aluminium phase. At depths greater than about 60 km, dense garnet becomes the aluminium bearing mineral. Some kimberlites contain xenoliths of eclogite which is considered to be the high pressure metamorphic product of oceanic basaltic crust as it descends into the mantle along subduction zones. (Blatt, 1996) Earth cutaway from core to exosphere. ... Basalt Basalt is a common gray to black volcanic rock. ... Hewn kimberlite core sample from the James Bay Lowlands region of Northern Ontario, Canada. ... Lamproite is a peralkaline volcanic rock. ... Lamprophyres (Greek Lampros, bright, and the terminal part of the word porphyry, meaning rocks containing bright porphyritic crystals) are a group of rocks containing phenocrysts, usually of biotite and hornblende (with bright cleavage surfaces), often also of olivine and augite, but not of feldspar. ... Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse grained or phaneritic texture. ... Peridotite Peridotite is a dense, coarse-grained rock, consisting mostly of the minerals olivine and pyroxene. ... The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. ... Lherzolite is a type of ultramafic igneous rock. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. ... The garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons. ... Eclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. ... Categories: Geology stubs | Plate tectonics ...


References

  • Blatt, Harvey, and Robert J. Tracy (1996) Petrology, W. H. Freeman, 2nd ed. ISBN 0-7167-2438-3
Wikimedia Commons has media related to:
Xenoliths

  Results from FactBites:
 
xenocryst - definition of xenocryst by the Free Online Dictionary, Thesaurus and Encyclopedia. (76 words)
xenocryst - definition of xenocryst by the Free Online Dictionary, Thesaurus and Encyclopedia.
A crystal foreign to the igneous rock in which it occurs.
This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.
Flickr: Xenocryst @ Antares Scorpii (113 words)
I want a free Pro account - Contest
A bit more about Xenocryst @ Antares Scorpii...
Xenocryst @ Antares Scorpii doesn't have any testimonials yet.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m