What are paired meteorites?
Paired meteorites are separate specimens that turn out to come from the same fall, even though they were found at different times or places and may have been given different names.
When a meteoroid breaks up in the atmosphere it can scatter many fragments over a strewn field, an oval area that may stretch for kilometres. If all the pieces are recovered together after a witnessed fall, they share one name. But in deserts and in Antarctica, fragments of a single fall are often found years apart, by different people, and catalogued separately before anyone realises they belong together. Such specimens are described as paired.
Pairing is common in dense collection areas. Antarctic ice can concentrate fragments of one fall in the same blue-ice field, and Saharan finds pass through traders who may sell pieces of the same stone to different buyers, so one fall can end up with several Northwest Africa (NWA) numbers. A well-known example is the Martian breccia NWA 7034, "Black Beauty", which has several paired stones catalogued under other numbers. Some Antarctic meteorites have dozens of recorded pairings.
Scientists establish pairing by comparing evidence. The meteorites should have the same classification, matching mineral chemistry and textures, and similar weathering. A strong test is the cosmic-ray exposure age, the time a body spent in space as a small object, measured from isotopes made by cosmic rays: fragments of the same meteoroid should give the same age. Terrestrial age, how long the stones have lain on Earth, should also agree.
Pairing matters for counting and for science. Without it, a single fall could be mistaken for several, distorting statistics on how common each meteorite type is. For rare types such as lunar or Martian meteorites, knowing which stones are paired tells us how many separate impacts launched them from their parent world. Collectors also care, because pairing affects how much material of a given meteorite really exists.