What is carbonaceous chondrite?

Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 8 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites. The C chondrites represent only a small proportion (4.6%)of meteoritic falls.
Some famous carbonaceous chondrites are: Allende, Murchison, Orgueil,Ivuna,Murray,Tagish lake, and Sutter'sMill.