Many commets have both type I and type II tails. Comets are concentrated in within a 50,000 AU radius Oort cloud with orbits having near random distribution with respect to the ecliptic plain of the solar system. Other, less favored, theories include condensation at great range near the dense portion of the Oort cloud or by ejection of volcanic gases from the planets within the solar system. Stony are the most common, include ones having little evidence of differntiation.
Carbonaceous chondrites contain carbon and volatile elements and compounds.
Chondrules may be formed by fast cooling. Radiometric dating gives ages on the order of the age of the solar system. Exposure ages of stony meteorites are much younger, indicating an origin due to collision in the asteroid belt. Some meteors and reaching earth may be devolatilized comet cores. A puzzle is why so many meteroites reaching earth are chondrites, more indicative of a product of primary condensation and accretion as a small body rather than fragmentation of a large planet-sized object at the orbital distance of the asteroid belt.