The most primitive carbonaceous chondrites have never been heated above 50C!
There is for example a certain spectral match between the reflectance spectra of the CM chondrites and the largest asteroid of our solar system, 1 Ceres - an irregular dark chunk of matter in the size of Texas.
However, recent research has found an even closer match, at least for Murchison - the asteroid 19 Fortuna which is a good candidate to be the lost parent body of this peculiar meteorite and maybe of the other CM chondrites, too.
Most of them contain water or minerals that have been altered in the presence of water, and some of them contain larger amounts of carbon as well as organic compounds.
This is especially true for the carbonaceous chondrites that have been relatively unaltered by heating during their history.
Otherwise, the water would have evaporated quite rapidly and the hydrous phyllosilicates would have been metamorphosed into other minerals due to the loss of water.
This group is named for its type specimen, the meteorite of Mighei, which fell in Ukraine in 1889, and it has many more members than the previous group.
In that mixture of phyllosilicate and magnetite, similar to the matrix of the CI chondrites, one also finds light-coloured inclusions.
These high-temperature silicates are lacking in the CI group.
Most CV chondrites belong to petrologic type 3, and only one has been found to belong to type 2 as well as one other that has been classified as type 4.
The structure and composition of these carbonaceous chondrites is more close to that of ordinary chondrites.
Carbonaceous chondrites or C chondrites represent some of the most pristine matter known, and their chemical compositions match the chemistry of the Sun more closely than any other class of chondrites.