Carbonaceous chondrite
The carbonaceous chondrites are a special form of stone meteorites dar.
They contain a high proportion of carbon ( up to 3% ) which is in the form of graphite, carbonates, and organic compounds, including amino acids. They also contain water and minerals that have been changed by the influence of water. The carbonaceous chondrites were not exposed to higher temperatures, so that they were scarcely changed by thermal processes. Some carbonaceous chondrites such as the Allende meteorite contain calcium - aluminum - rich inclusions ( CAIs ). These are compounds that condensed from the early solar nebula and are likely to represent the earliest formed in the solar system minerals.
Some primitive carbonaceous chondrites such as the Murchison CM chondrite, contain presolar minerals, including silicon carbide, and only tiny nanometer-sized diamonds, which were obviously not formed in our solar system. These presolar minerals were probably the explosion of a nearby supernova or in the vicinity of a pulsating red giant (more precisely, a so-called AGB star ) formed before they came into the cloud of matter from which our solar system was formed. With such stellar explosions pressure waves are released, can compress the clouds of matter in their environment, which may lead to the formation of new stars and solar systems.
Based on their chemical composition, the carbonaceous chondrites in the groups CI, CB, CM, CV, CO, CR, CK and CH are divided.
- CI chondrites, named after the case of Ivuna, Tanzania, contain a high water content (up to 20 % ) and numerous organic compounds such as amino acids. They have not been heated above 50 ° C during the course of their lives and may have originated in the outer solar system. Maybe they are part of a former comet. The CI chondrites contain no visible chondrules, as they were destroyed by the water.
- CB chondrites ( Bencubbin, Australia ) are each about 50 % of nickel - iron and silicates. Despite their high iron content, the meteorites are not counted towards the stone -iron meteorites. Rather, they are closely related to the CR chondrites due to their mineralogical properties and chemical composition. Representatives of this group are also referred to as " Bencubbiniten ". The Bencubbinite may have occurred in the boundary layer between the nickel-iron core and the silicate mantle of a C asteroid.
- CM chondrites ( Mighei, Ukraine) are similar to CI chondrites by their chemical composition, but contain less water. They have distinct chondrules and often inclusions of CAIs. The CM chondrites also likely to be formed in the outer solar system.
- CV chondrites ( Vigarano, Italy) are similar in their chemical composition and structure of the ordinary chondrites ago. However, they contain, in contrast to this meteorite trail of water and organic substances. CV chondrites have clearly visible chondrules and CAIs numerous.
- CO chondrites ( Ornans, France) are chemically similar in the CV chondrites. However, they are darker and have very small chondrules and CAIs on much less.
- CR chondrites ( Renazzo, Italy) are similar to CM chondrites, however, contain more nickel-iron and iron sulfide. Spectroscopic studies show a match with Pallas, the second largest asteroid of the main asteroid belt. Maybe the CR chondrites originate from this celestial body.
- CK chondrites ( Karoonda, Australia) have a high content of the mineral magnetite that lends a meteorite matte black exterior. CK chondrites contain different sized chondrules and occasional inclusions of CAIs.
- CH Chondrites (high -iron ) containing a high proportion of nickel - iron, often more than 50 weight percent.
- Meteorites