Chondrites were formed by the accretion of particles of dust and grit present in the primitive Solar System which gave rise to asteroids over 4.54 billion years ago.

Another indication of their age is the fact that the abundance of non-volatile elements in chondrites is similar to that found in the atmosphere of the Sun and other stars in our galaxy.

Many chondritic asteroids also contained significant amounts of water, possibly due to the accretion of ice along with rocky material.

As a result, many chondrites contain hydrous minerals, such as clays, that formed when the water interacted with the rock on the asteroid in a process known as aqueous alteration.

These events caused a variety of effects, ranging from simple compaction to brecciation, veining, localized melting, and formation of high-pressure minerals.

The remainder of chondrites consists of fine-grained (micrometre-sized or smaller) dust, which may either be present as the matrix of the rock or may form rims or mantles around individual chondrules and refractory inclusions.

[12] An article published in 2005 proposed that the gravitational instability of the gaseous disk that formed Jupiter generated a shock wave with a velocity of more than 10 km/s, which resulted in the formation of the chondrules.

Each chondrite group has a distinctive mixture of chondrules, refractory inclusions, matrix (dust), and other components and a characteristic grain size.

[17] Chondrites can also be categorized according to their petrologic type, which is the degree to which they were thermally metamorphosed or aqueously altered (they are assigned a number between 1 and 7).

[19] The majority of enstatite chondrites have either been recovered in Antarctica or have been collected by the American National Weather Association.

[19] E-type chondrites are among the most chemically reduced rocks known, with most of their iron taking the form of metal or sulfide rather than as an oxide.

[11] They contain abundant chondrules, sparse matrix (10–15% of the rock), few refractory inclusions, and variable amounts of Fe–Ni metal and troilite (FeS).

Most, but not all, ordinary chondrites have experienced significant degrees of metamorphism, having reached temperatures well above 500 °C on the parent asteroids.

"Primitive," in this sense, means that the abundances of most chemical elements do not differ greatly from those that are measured by spectroscopic methods in the photosphere of the sun, which in turn should be well-representative of the entire Solar System (note: to make such a comparison between a gaseous object like the sun and a rock like a chondrite, scientists choose one rock-forming element, such as silicon (Si), to use as a reference point, and then compare ratios.

CI chondrites seem to be nearly identical in composition to the sun for all but the gas-forming elements (e.g., hydrogen (H), carbon (C), nitrogen (N), and noble gases: helium (He), neon (Ne), argon (Ar) etc.).

These chondrites show little evidence of the effects of aqueous alteration: Some workers have extended the Van Schmus and Wood metamorphic scheme to include a type 7, although there is not consensus on whether this is necessary.

Type 7 chondrites have experienced the highest temperatures possible, short of that required to produce melting.

The formation of rivers and lakes on the asteroid is thought to have been unlikely if it was sufficiently porous to allow the water to percolate towards its interior, as occurs in terrestrial aquifers.

It has been proposed that the amino acids were synthesized close to the surface of a planetoid by the radiolysis (dissociation of molecules caused by radiation) of hydrocarbons and ammonium carbonate in the presence of liquid water.