Meteorites classification

The ultimate goal of meteorite classification is to group all meteorite specimens that share a common origin on a single, identifiable parent body. This could be a planet, asteroid, Moon, or other current Solar System object, or one that existed some time in the past (e.g. a shattered asteroid). However, with a few exceptions, this goal is beyond the reach of current science, mostly because there is inadequate information about the nature of most Solar System bodies (especially asteroids and comets) to achieve such a classification. Instead, modern meteorite classification relies on placing specimens into "groups" in which all members share certain key physical, chemical, isotopic, and mineralogical properties consistent with a common origin on a single parent body, even if that body is unidentified. Several meteorite groups classified this way may come from a single, heterogeneous parent body or a single group may contain members that came from a variety of very similar but distinct parent bodies. As such information comes to light, the classification system will most likely evolve.

Beyond the assignment of meteorites into groups (see above), which essentially universally accepted, there is no consensus among researchers as to what hierarchy of classification terms is most appropriate. For chondrites, groups may be divided into subgroups where there are features that distinguish certain meteorites from the others in the group, but it is thought that all still come from a single parent body. It is also fairly common for groups that seem to be closely related to be referred to as clans. In turn, groups or clans that appear to be loosely related are often referred to as chondrite classes (e.g., carbonaceous chondrites, enstatite chondrites, and ordinary chondrites). But higher order terms for aggregating groups of meteorites tend to be somewhat chaotic in the scientific and popular literature. There is little agreement on how to fit nonchondritic meteorite groups into an overall scheme.

Several other classification terms are in widespread use:

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