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"H" stands for "high metal" because CH chondrites may contain up to as much as 40% of metal. [16] That makes them one of the most metal-rich of any of the chondrite groups, second only to the CB chondrites and some ungrouped chondrites such as NWA 12273. The first meteorite discovered was ALH 85085. Chemically, these chondrites are closely ...
CB chondrites occur in two types, both of which are similar to CH chondrites in that they are very depleted in volatile elements and rich in metal. CB a (subgroup a) chondrites are coarse grained, with large, often cm-sized chondrules and metal grains and almost no refractory inclusions. Chondrules have unusual textures compared to most other ...
Again, different kinds of chondrites contain different ranges of chondrule sizes: they are smallest in CH, CM, and CO chondrites (see meteorite classification), moderately large in CR, CV, L, LL, and R chondrites, and largest in some CB chondrites (see table). Other chondrite groups are intermediate between these.
The CM group most resembles the CI and CO chondrites; a CM–CO is sometimes described. [7] [8] [9] All three groups contain clearly anomalous 50 Ti and 54 Cr isotopes. [10] [11] Though the C-chondrites are far rarer than ordinary chondrites, the CM group is "the most abundant type of" them.
Carbonaceous chondrites compose about 4 percent of all meteorites observed to fall from space. Prior to 1969, the carbonaceous chondrite class was known from a small number of uncommon meteorites such as Orgueil, which fell in France in 1864. Meteorites similar to Allende were known, but many were small and poorly studied. [3]
They are classified on the same rank (historically called "Class") and lying between chondrites and achondrites. They are called primitive because they are achondrites that have retained much of their original chondritic properties. Very characteristic are relic chondrules and chemical compositions close to the composition of chondrites. These ...
In fact, the term "stony iron" is a misnomer as currently used. One group of chondrites (CB) has over 50% metal by volume and contains meteorites that were called stony irons until their affinities with chondrites were recognized. Some iron meteorites also contain many silicate inclusions but are rarely described as stony irons.
Nagy B, Claus G, Hennessy DJ (1962) Organic Particles Embedded in Minerals in Orgueil and Ivuna Carbonaceous Chondrites. Nature 193 (4821) p. 1129; Fitch FW, Anders E (1963) Organized Element - Possible Identification in Orgueil Meteorite. Science 140 (357) p. 1097