7 - Meteorites and the Standard Abundance Distribution (SAD)

Summary

An Overview

We may divide the meteorites into three broad categories, the stones, the stony-irons, and the irons. Meteorite samples are described as “falls” or “finds.” If a meteorite is observed to fall, and brought to a museum curator, it is called a fall. Finds are meteorites that have not been seen to fall, or at least not by the person who discovers them.

It is now reasonable to speak of two major divisions of meteorites – those discovered in the last several decades in Antarctica, and all of the rest. The Antarctic meteorites have roughly doubled the available samples of solid cosmic debris. It is difficult to know precisely how many independent falls are represented, since all of these samples are finds. However, we must leave differences among the Antarctic and non-Antarctic samples to the references (see Koeberl and Cassidy 1991).

The non-Antarctic meteorites are named by the location of the fall or find. The names are often exotic. For the Antarctic meteorites, locations are also used for the names, but these are supplemented by alphanumerical codes. Most of the world's classified (non-Antarctic) meteorites are listed in the Catalogue of Meteorites (Graham, Bevan, and Hutchison 1985). They include listings for selected Antarctic meteorites.

Most of the meteorites in museums are irons, while the opposite is true of falls – most of the latter are stones.