Carbonaceous chondrites, including Allende, are the most primitive meteorites, and contain the most primitive known matter.

For this reason they are also called primitive meteorites.

They include some of the most primitive known meteorites.

This type of meteorite is rich in carbon and among the most chemically primitive meteorites.

Among the high temperature materials some are already well known components of primitive meteorites; rocks from asteroids that formed between Mars and Jupiter.

It is now known from study of the sun and primitive meteorites that the solar system was initially almost homogeneous in isotopic composition.

The single exception to this lies with the presolar grains found in primitive meteorites.

The Renazzo meteorite was discovered in Italy in 1824 and is one of the most primitive meteorites known.

Some presolar grains in primitive meteorites consist of hibonite.

Ma has been leading a nano mineralogy investigation, since 2007, of primitive meteorites, including the well studied Allende meteorite.