Class of carbonaceous chondrites named after the Mighei meteorite that fell in Ukraine in 1889. They represent samples of incompletely serpentinized primitive asteroids and have experience extremely complex histories. CM meteorites are generally petrologic level type 2 though a few examples of CM1 and CM1/2 also exist. Compared to CI chondrites, they have about half the water content, show less aqueous alteration, and retain some well-preserved small chondrules (diameter s <0.5 mm; 10-40 vol. %) and CAIs (~5 vol. %). Like CI chondrites, they also contain a wealth of organic material: more than 230 different amino acids have been identified in the Murchison meteorite. Comparisons of spectra point to the asteroid 19 Fortuna or, possibly, the largest asteroid, 1 Ceres, as candidate parent bodies.
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