Ordinary Chondrites - Main Page

The chondrites of this clan are designated as "ordinary" just because they represent the most common class of stony meteorites on Earth, accounting for about 80% of all witnessed meteorite falls. But as genuine pieces of primordial matter, ordinary chondrites are everything else but ordinary since they are more rare than gold or diamonds, and – with crystallization ages of about 4.5 billion years – much older than any rock or any mineral known on our planet.

More importantly, ordinary chondrites might not be that common at all when it comes to the actual distribution of chondritic matter in our solar system. More recent studies suggest that the high percentage of ordinary chondrite falls might only be due to the coincidence of the crossing orbits of certain near-Earth asteroids – the so-called NEAs – and the orbit of the Earth. If the majority of those NEAs would be of ordinary chondritic composition this would result in a higher percentage of ordinary chondrite falls. Thus, ordinary chondrites might not be that ordinary at all.

In terms of petrology and mineralogy, all OCs (ordinary chondrites) are primarily composed of of the minerals olivine, different types of orthopyroxene, and a certain percentage of more or less oxidized nickel-iron. Based on the differing content of metal, and distinct mineral compositions the members of the OC clan are classified into three distinct main groups that are designated as the H chondrites (accounting for 33.8% of all witnessed falls), the L chondrites (representing about 37.2% of all witnessed falls), and the LL chondrites (accounting for just 8.1% of all witnessed falls). Besides that, there are several so-called transitional ordinary chondrites which do not fit neatly into one of the existing classes. They do account for about 1% of all witnessed falls, and will be discussed on a separate page.

Learn more about the types and the groups of ordinary chondrites – just follow the respective links.