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Stony-meteorites

 

 

Carbonaceous Chondrites

 

Carbonaceous Chondrites

(C-Chondrites)

CI-Chondrites

CM-Chondrites

CV-Chondrites

CO-Chondrites

CR-Chondrites

CK-Chondrites

CH-Chondrites

 

New: Microscopical views od Ck 4

Carbonaceous Chondrites

The carbonaceous Chondrites, also C-Chondrites, probably represent the oldest well known matter and resemble in their chemical make-up more the Sun than all other Chondrites. Typical is their content of water and minerals, changed by water, their content of carbon and organic compounds as well as the fact, that most of them in the course of their existence scarcely changed by thermal processes. The most primitive Carbonaceous Chondrites in the course of their history never were heated over a temperature of 50 degrees centigrade! In spite of all these commonalities, the Carbonaceous Chondrites are still quite different according to place of origin in the presolar primeval nebula and are subdivided into several groups. The most important are mentioned below:

 

CI-Chondrites

CI-Chondrites got their name after their fall in Ivuna, Tansania, and only a handful of these rare meteorites is known. They are the most primitive and unsightly meteorites at all- and yet also the most interesting. Petrologically almost all belong to class 1; only one CI 2-Chondrite is known. They contain almost no visible chondrules, however a water content of up to 20% and numerous organic compounds as well as amino acids and other modules of life. Possibly they have their origin in comets, but certainly they come from the external areas of our solar system, which is apparent by the fact, that in the course of their development they never were heated over 50 degrees centigrade.

 

CM-Chondrites

The numerically better represented group of the CM-Chondrites is named after their fall at Mighei, Ukraine. The CM-Chondrites almost all belong to the petrological class 2. They contain less water than the CI-Chondrites, besides this, in their mineralogical composition they are quite similar to them. Also they contain organic substances, like amino acids, but in addition they possess clearly visible chondrules and frequently inclusions of so-called CAIs (Calcium-Aluminium-Inclusions). These CAIs contain microscopic small diamonds with isotopical signatures, which point not only to a substantially higher age than that of our solar system, but rather it obviously comes from interstellar matter - matter from other star systems, which at the origin of our solar system was included and preserved in the CAIs. Originally, the meteorites of the CM-group could also come from comets; they possibly also are descendants of the largest asteroid in our solar system, 1 Ceres, who shows a very similar reflection spectrum.

 

CV-Chondrites

CV-Chondrites are named after their fall at Vigarano, Italy, and encompass the petrological classes 3 and 4. In their structure and chemical compound, they resemble more the normal Chondrites, however contain in contrast to these also traces of water, organic substances and especially many big chondrules and CAIs - a typical feature of the CV-group. An especially well known CV-meteorite is the fall of Allende, Mexico, that happened in 1969, shortly before the first manned Moon landing. At that time almost two tons of the rare and scientifically so valuable matter fell on Earth - enough material to equip not only all research laboratories, but rather also all private collectors therewith!

 

CO-Chondrites

The CO-Chondrites are named after their fall at Ornans, France, and petrologically always belong to the class 3. Chemically they resemble the CV-Chondrites, with whom they form one clan, but they differ already on the first view through their black appearance, their very few chondrules and through substantially less inclusions of CAIs. Moreover they contain clearly visible inclusions of nickel iron, which in polished disks appear as tiny schimmering flakes.

 

CR-Chondrites

CR-Chondrites were named after the fall of Renazzo, Italy, and belong to the petrological classes 2 and 3. Originally they were incorporated into the CM-group, but in the mean time it is clear that they represent one characteristic group. They possess usually large, clearly distinguished chondrules and contain relatively much nickel iron in contrast to the CM-Chondrites as well as iron sulfide. There is a correspondence of the reflection spectrums of the CR-Chondrites with the second largest ssteroid in our solar system, 2 Pallas, that possibly is the mother body of these very rare Carbonaceous Chondrites.

 

CK-Chondrites

CK-Chondrites, named after their fall at Karoonda, Australia, encompass the petrological classes 3 to 6 and originally were held for representatives of the CV-group. Cut slices of this meteorite appear, based on a high share of magnetite, usually dull and black, interspearsed by inclusions of differently sized chondrules and occasionally by CAIs. Many CK-Chondrites moreover show shock veins, veins of rock melted by pressure, what refers to an eventful past of the CK mother body and/or on an impact event. Until now the exact place of origin of this very rare meteorites group however has become not sufficiently certain.

 

CH-Chondrites

This very little group of Carbonaceous Chondrites is exceptionally not named after a fall, but rather after a special characteristic: the "H" stands for "High Iron" and designates the for this group characteristic high share in nickel iron that often can amount to over 50% of the total mass! Alone this fact could suffice to designate the CH-group as a form of Stony-iron meteorite, but the familiarity of the carbon rock share with the meteorites of the CR-group has let to the fact that one incorporated it into the class of the Carbonaceous Chondrites. Petrologically the well known CH-Chondrites all belong to to the group 3, and a not yet clarified narrow connection exists to another group of Chondrites, the Bencubbinites, that are described further below.

Ordinary Chondrites
Enstatites, Rumurutis and other Chondrites
Achondrites