chondritic /kon drit"ik/, adj.
/kon"druyt/, n.
a stony meteorite containing chondrules.
[1880-85; CHONDR- + -ITE1]

* * *

 in general, any stony meteorite characterized by the presence of chondrules. The only meteorites classified as chondrites that do not contain chondrules are the CI group. These meteorites are so heavily altered by water that it is unclear whether they once contained chondrules. All other aspects of these objects, however, indicate that they belong with the chondrites.Chondrules are roughly spherical inclusions, typically hundreds of micrometres to a few millimetres in size. They are made up of silicates, metal, and sulfide, and they appear to have formed as molten droplets at high temperatures in the early solar nebula. The chondrules are set in a fine-grained matrix that binds them together. Chondrites are divided into three main classes based on their bulk chemical compositions, oxygen isotopic compositions, and petrology. These are carbonaceous chondrites, ordinary chondrites, and enstatite chondrites.

      Chondrites are the most abundant meteorite class, constituting more than 85 percent of meteorite falls. Like most meteorites, chondrites originated in the asteroid belt where collisions and gravitational perturbations put them into Earth-crossing orbits. Chondrites formed about 4.56 billion years ago as part of the formation of their parent asteroids. They are chemically quite similar to one another and, apart from the most volatile elements (e.g., hydrogen and helium), to the Sun. Since most of the mass of the solar system is in the Sun, the initial composition of the solar system would have been similar to the Sun's composition. The great age of the chondrites, their primitive chemistry, and the relatively unmodified state of their constituents all suggest that these meteorites retain a record of processes that happened in the solar nebula before and during the phase of planet formation. Nevertheless, the meaning of this record remains to be fully deciphered. The chondrites also contain material, including organic matter and tiny grains that formed around dying stars, that predates the formation of the solar system.

      Most chondrites contain the anhydrous silicate minerals olivine, orthopyroxene and clinopyroxene, and plagioclase, as well as the nickel-iron minerals kamacite and taenite, and the iron sulfide troilite. Some contain claylike hydrous silicates.

Conel M.O'D. Alexander

* * *

Universalium. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • chondrite — ● chondrite nom féminin (grec khondros, cartilage) Inflammation d un cartilage. ● chondrite nom féminin (grec khondritês, fait de gruau) Météorite constituée de chondres. (Les chondrites représentent 80 % des météorites.) chondrite [kɔ̃dʀit] n. f …   Encyclopédie Universelle

  • Chondrite — Chon drite, n. [Gr. ? a grain (of wheat or spelt), cartilage.] (Min.) A meteoric stone characterized by the presence of chondrules. [1913 Webster] …   The Collaborative International Dictionary of English

  • Chondrīte — Chondrīte, eine Gruppe der Meteorsteine (s.d.) …   Meyers Großes Konversations-Lexikon

  • chondrite — [kän′drīt΄] n. [Ger chondrit < chondrum, a chondrule (< Gr chondros: see CHONDRO ) + ITE1] the type of stony meteorite that contains chondrules chondritic [kän drit′ik] adj …   English World dictionary

  • Chondrite — Allende (Meteorit) L6 Chondrit Holbrook. Schnittfläche, helle Körner sind Metall. Höhe 5 cm. Chondrite bilden mit einem Anteil von etwa 86 Prozent die größte Klasse der …   Deutsch Wikipedia

  • Chondrite — Chondrules bien visibles sur une tranche d un fragment de la météorite Allende. Chondrite (se prononce kondrite) est un terme utilisé en astronomie pour désigner un certain type de météorites pierreuses (moins de 35 % de métal). Cette… …   Wikipédia en Français

  • Chondrite — Not to be confused with Chondrodite. A specimen of the NWA 869 chondrite (type L4 6), showing chondrules and metal flakes Chondrites are stony meteorites that have not been modified due to melting or differentiation of the parent body. They… …   Wikipedia

  • Chondrite CI — Les chondrites CI ou chondrites du type CI, parfois appelées chondrites C1, sont des météorites pierreuses appartenant aux chondrites carbonées. De toutes les météorites leur composition chimique montre la plus grande affinité avec l abondance… …   Wikipédia en Français

  • Chondrite de type H — Chondrite de type H5 Sud Maroc Les chondrites ordinaires de type H sont le type de météorite le plus courant. Elles constituent environ 40 % des météorites, 46 %des chondrites ordinaires et 44 % des chondrites[1]. Le nom vient de… …   Wikipédia en Français

  • Chondrite carbonee — Chondrite carbonée Une chondrite carbonée ou chondrite de type C est une météorite chondritique. Portail de l’astronomie Ce document provient de « Chondrite carbon%C3%A9e ». Catégorie : Classification des météorites …   Wikipédia en Français

  • Chondrite ordinaire — Les chondrites ordinaires (parfois appelées chondrites O) sont un type de météorites chondritiques. Elles sont de loin les plus nombreuses et constituent 87 % de toutes les observations. C est la raison pour laquelle elles ont été qualifiées …   Wikipédia en Français

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”