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Meteorite Book Chondrules are classified into several groups based on texture and chemical-mineral characteristics; the most common are shown below with petrographic examples. In barred olivine (BO) chondrules, olivine crystallized in bar-like form where parallel plates of olivine are in optical continuity, usually with a spherical shell of olivine (“armored”). Porphyritic chondrules have crystals of olivine (PO), pyroxene (PP) or both minerals (POP) surrounded by a glassy matrix, which is petrologically referred to as mesostasis. www4.nau.edu /meteorite/Meteorite/Book-Chondrules.html   (1019 words)

chondrule A roughly spherical aggregate of coarse crystals formed from the rapid cooling and solidification of a melt at about 1400°C. Large numbers of chondrules are found in all chondrites except for the CI group of carbonaceous chondrites. Chondrules are typically 0.5 to 2 mm in diameter and are usually composed of iron, aluminum, or www.daviddarling.info /encyclopedia/C/chondrule.html   (203 words)

PSRD: Making Sense of Droplets Inside Droplets Chondrules are millimeter-sized frozen droplets of molten silicate. Dating the time of formation of individual chondrules cannot be done unambiguously from a bulk isotopic analysis of a chondrule--magnesium and aluminum isotopes must be measured on separate mineral grains in a chondrule. All, that is, until Itoh and Yurimoto found a chondrule inside a CAI, implying contemporaneous formation of chondrules and CAIs, in accord with the interpretation Martin Bizzarro and his colleagues made from their isotopic data. www.psrd.hawaii.edu /May05/chondrulesCAIs.html   (2111 words)

Masayuki Uesugi: Research   (Site not responding. Last check: 2007-10-09) Chondrule formation due to nebular shock waves: Previous numerical simulations have shown that the thermal history of the shockformed chondrule seems quite consistent with the results of the chondrule texture reproduction experiments (e.g. In the nebular shock wave heating model, molten chondrules in the shocked nebular gas generally have a supersonic velocity relative to the gas and are exposed to the momentum flux of the gas flow. If the iron inclusions observed in the natural chondrules (see figure) had existed inside of the chondrules during melting of the chondrules by the nebular shock wave, the final distribution of them must come under the influence of the internal flow and the apparent gravity. jupiter.geo.kyushu-u.ac.jp /~uesugi/research.html   (468 words)

Chondrule. Who is Chondrule? What is Chondrule? Where is Chondrule? Definition of Chondrule. Meaning of Chondrule. Many meteorites are full of tiny silicate spherules which are called chondrules (from Greek chondros, grain). Hence, from the abundance of chondrules within these meteorites, it follows that an understanding of the formation of chondrules is important to understand the initial development of the planetary system. It is widely accepted that chondrules are formed by a rapid heating within minutes or less of solid precursor material to temperatures between 1500°C and 1900°C and subsequent melting, followed by a cooling within a few hours. www.knowledgerush.com /kr/encyclopedia/Chondrule   (275 words)

Chondrule Melting: Key Clue To Life In The Universe Because shocks would melt chondrules early in the solar nebula's evolution, the results are consistent with the common idea that chondrule formation was a prerequisite to the formation of planets in general. This radiation is absorbed by chondrules that haven't reached the shock front yet, and by chondrules that have already passed through it. Compound chondrules are overwhelmingly produced in regions with high chondrule densities, so the extra heating and faster cooling of compound chondrules is easily explained by this shock model. unisci.com /stories/20021/0326021.htm   (1063 words)

Fred's Chondrule Page   (Site not responding. Last check: 2007-10-09) Chondrules are small (~1 mm diameter) silicate particles that make up large components of many of the meteorites that fall on Earth. Whatever formed the chondrules happened over a reltatively small area in the nebula because different types of chondrules exist, so their formation histories would be slightly different. I am currently trying to understand the conditions necessary to form chondrules in a nebular shock and from that deduce which of the mechanisms can produce shocks that are of proper strength and scale to form chondrules in a manner that is consistent with the meteoritic data. www.lpl.arizona.edu /~fciesla/work/chondrule   (651 words)

st robert poster.doc   (Site not responding. Last check: 2007-10-09) Texturally the sample is characterized by approximately 30 % chondrules of varying textures (mainly barred or porphyritic) in a matrix of chondrule fragments and native iron. The chondrules are composed mainly of olivine and orthopyroxene, in a matrix of extremely fine grained (average grain size less than 5 microns) recrystallized glass. Chondrule is mostly orthopyroxene (brighter areas) with fined grained clinopyroxene and feldspar (dark areas). castaing.eps.mcgill.ca /meteoriteposter/poster.html   (1399 words)

* Chondrule - (Astronomy): Definition Chondrules are composed of iron, aluminum, and magnesium silicate rock Most chondrules are 0.5 to 2 millimeters in size and are composed of olivine and pyroxene, with smaller amounts of glass and iron-nickel metal... Some stony meteorites contain small glassy spheres called chondrules, and objects with these spheres are known as chondrites, a sub-class of the stony meteorites... en.mimi.hu /astronomy/chondrule.html   (350 words)

Connolly's Chondrule Page   (Site not responding. Last check: 2007-10-09) Chondrules are round silicate spheres (approximately 2mm in diameter on average) composed largely of olivine and pyroxene with minor amounts of Fe-Ni metals and sulfides that have igneous textures. Chondrules are argued rather convincingly to have formed as isolated droplets within our solar nebula, as opposed to in some asteroid/parent body environment. Barred olivine chondrules were discovered to represent a maximum temperature limit that chondrules could have experienced and still produce textures from incomplete melts. www.gps.caltech.edu /~vorlon/chondrule1.html   (602 words)

PSRD: Relicts from Solar System Birth Chondrules comprise the remaining 30% of HH 237 and QUE 94411. Note that the cryptocrystalline chondrules are associated with zoned metal; in fact, metal appears to enclose one of the chondrules. The skeletal olivine chondrules tend to be enriched in the elements expected to condense at the highest temperature (calcium, aluminum, titanium, rare earth elements), while the cryptocrystalline chondrules contain much lower amounts of these elements. www.psrd.hawaii.edu /Mar01/relicts.html   (1898 words)

Meteorite Thin Sections This chondrule (pictued at right) is fairly complex - containing elements of a barred olivine and porphyritic olivine chondrule. Chondrules of this type are difficult to interpret but are likely produced through multiple phases of chondrule formation - the barred olivine chondrule may, for example, be a precurser chondrule (i.e. This "incorporation" likely is the result of a second stage of chondrule formation in which material that had accreted to the original chondrule was heated to form a second chondrule. www3.sympatico.ca /jeff.rowell/Ghubara.htm   (128 words)

Chondrule -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-09) Many (Stony or metallic object that is the remains of a meteoroid that has reached the earth's surface) meteorites are full of tiny (A salt or ester derived from silicic acid) silicate spherules which are called chondrules (from Greek chondros, grain). Chondrites represent the oldest solid material within our (The sun with the celestial bodies that revolve around it in its gravitational field) solar system and are believed to be the building blocks of the (Any of the celestial bodies (other than comets or satellites) that revolve around the sun in the solar system) planetary system. Chondrules are formed by a rapid heating within minutes or less of solid precursor material to temperatures between 1500°C and 1900°C and subsequent melting, followed by a cooling within a few hours. www.absoluteastronomy.com /encyclopedia/c/ch/chondrule.htm   (585 words)

Geotimes - May 2005 - Early Jupiter spawned early meteorites The new 3-D model shows the chondrules as part of the larger evolution of the solar system, from birth approximately 4.5 billion years ago until the early sun had accreted most inner-nebula materials 3 million years later. Early studies suggested that the only way to melt the silicates in chondrules in a manner consistent with meteorite observations would have been to heat the grains to melting temperatures multiple times, a process that could be achieved by shockwaves only if they are traveling at least 6 to 9 kilometers per second. Chondrules, along with larger inclusions and microscopic matrix particles, are the principal components of chondrites, the most primitive meteorites. www.geotimes.org /may05/NN_chondrules.html   (647 words)

Chondrule - Wikipedia, the free encyclopedia Many meteorites are full of millimeter-sized silicate spherules which are called chondrules (from Greek chondros, grain), suspended in the younger matrix of dust grain material of meteorites and interplanetary dust particles. Chondrules are formed by a rapid heating within minutes or less of solid precursor material to temperatures between 1500°C and 1900°C and subsequent melting, followed by a cooling within an hour (Wood, 1999) or a few hours. However, the environmental setting, the energy source for the heating, and the precursor material are not known. en.wikipedia.org /wiki/Chondrule   (468 words)

Chondrules and the Protoplanetary Disk - Cambridge University Press   (Site not responding. Last check: 2007-10-09) Chondrules in primitive meteorites have excited and challenged scientists since they were first described nearly 200 years ago. Chondrules were made by some pervasive process in the early solar system that formed melted silicate droplets. This is the first comprehensive review of chondrules and their origins since a consensus developed that they were made in the disk of gas and solids that formed the Sun and planets 4.5 billion years ago. www.cambridge.org /aus/catalogue/catalogue.asp?isbn=0521552885   (691 words)

[No title]   (Site not responding. Last check: 2007-10-09) The models also suggest that, if chondrules were flash heated to liquidus temperatures (1800-2100 K for BO and PO chondrules) and subsequently cooled linearly, the cooling rates needed to prevent 1-2‰/amu isotopic fractionation of Fe in a 500mm radius chondrule even at pH2=10-6 are close to the upper limits set by experimental simulations. Chondrule mesostases may have exchanged K during cooling or on the parent bodies but it is less likely that the glass inclusions enclosed in olivine phenocrysts measured by [12] have exchanged. We have developed a simple 2 component model in which 500µm radius chondrules and 5µm radius dust, both with L-chondrite-like silicate compositions, are instantaneously heated to their peak temperature and then cool linearly to 1600 K when the integration is stopped. www.uark.edu /campus-resources/metsoc/alexande.htm   (1132 words)

[No title]   (Site not responding. Last check: 2007-10-09) Chondrule models tend to be strongly influenced by theoretical concepts, rather than being based on chondrule properties alone. Chondrule textures do not require a very short time at peak temperature, and are matched in simulation experiments using very long melting times. Chondrule Ages While it it is not always certain what events short-lived chronometers are dating, there is sufficient consistency beteen a number of systems [18-22] that we should consider the possibility that they give true ages. www.uark.edu /campus-resources/metsoc/hewins.htm   (1911 words)

Connolly's Chondrule Page   (Site not responding. Last check: 2007-10-09) Chondrites, and hence chondrules, are the remains or early planet-forming materials that did not get processed into planets, fall into the early active Sun, or get ejected from our solar system during its growing stage. Porphyritic chondrules consist of phynocrysts of olivine or pyroxene in a feldspathic glassy to microcrystalline groundmass. FeO-rich chondrules have porphyritic textures usually with a preponderance of well-formed crystals (euhedral) in a glassy mesostasis with a low abundance of opaque minerals. www.gps.caltech.edu /~vorlon/chondrulepage.html   (1024 words)

Chondrules The average chondrule size is millimeter in diameter, but it is not uncommon to have chondrules between 7 or 8 millimeters in diameter. So by understanding the processes that affected chondrules, we'll gain insight as to what processes were taking place as solids first formed in the solar nebula which could have determined how the nebula as a whole evolved over time." The majority of chondrites reside within the asteroid beld and bear witness to the early history of the solar nebula. www.saharamet.com /meteorite/chondrules/show.html   (222 words)

winners The chondrules and refractory inclusions (CAIs) in chondritic meteorites are the oldest known remnants of the processes which formed the sun, asteroids, and planets, so their study is central to cosmochemistry. The compositions of these chondrules will be used to infer their precursor components; these components will be compared to those inferred for chondrules from ordinary and carbonaceous chondrites, groups that formed in different regions of the solar nebula. Major themes of our chondrule research are (1) the temperature and crystallization history of individual chondrules, and (2) the evolution of the solar nebula during the period within which chondrule formation occurred. research.hq.nasa.gov /code_s/nra/current/NRA-02-oss-01-COS/winners.html   (12883 words)

Hewins 1997 The chondrule consists of olivine and low-Ca pyroxene grains in a glassy groundmass. Compound chondrule - This is a chondrule that consists of multiple, attached portions. Compound chondrules observed in thin sections, where the field of view is a little more than 1 mm across in both images. web.pdx.edu /~ruzickaa/G410/Hewins/glos7.html   (857 words)

Meteorite Thin Sections   (Site not responding. Last check: 2007-10-09) Compound RP chondrules with a crater in the child chondrule and in the primary chondrule (Lost Creek H3.8). Closup of the compound chondrule pictured above - note that the sibbling chondule contains a crater that must have formed prior to its attatchment to the primary. Chondrules in the Lost Creek meteorite often contain fractures such as the one pictured. www3.sympatico.ca /jeff.rowell/Craters.htm   (101 words)

ferromagnesian chondrule Comparison Table   (Site not responding. Last check: 2007-10-09) chondrule with extremely fine-grained intergrowths of pyroxene and glass with grain size less than 2 micrometers chondrule with a porphyritic mixture of olivine and pyroxene chondrule with thin needles of pyroxene radiating from a single point on the edge of the chondrule www.site.uottawa.ca:4321 /meteorites/ferromagnesianchondrule_table.html   (234 words)

Thin Section Photos   (Site not responding. Last check: 2007-10-09) This picture is in plane light showing chondrules and the slide as they would appear under a normal microscope. The chondrules had sharper edges and overall more crisp round shapes than those of a type 5 leading me to guess that this may be a petrological type 4 chondrite. Just to the left of center at the bottom is a somewhat distorted Barred chondrule but the unusual one is the coarse grained radial in the center, with the faint ring of grains surrounding it. home.earthlink.net /~jimmypaul/thinsections.htm   (298 words)

Meteorite Thin Sections NWA 801 - A very complex chondrule - the center shows the typical structure of a BO chondrule - this is surrounded by several rims - some containing small blebs of metal. A large anhedral olivine crystal is embeded into one side of the chondrule. BO chondrules are uncommon in CR2's - the majority of the chondrites being PO and POP. www3.sympatico.ca /jeff.rowell/CR2.htm   (214 words)

chondrule - Hutchinson encyclopedia article about chondrule   (Site not responding. Last check: 2007-10-09) In astronomy, small, round mass of the silicate minerals olivine and orthopyroxene. Chondrites (stony meteorites) are characterized by the presence of chondrules. Chondrules are thought to be mineral grains that condensed from hot gas in the early Solar System, most of which were later incorporated into larger bodies from which the planets formed. encyclopedia.farlex.com /chondrule   (116 words)

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