Ungrouped meteorite
A meteorite that does not fit into any recognised group, often marked with the abbreviation "ung".
Meteorites are sorted into groups when several specimens share the same minerals, chemistry and isotopes, implying a common parent body. Under the usual convention, a new group needs at least five unrelated members; two to four make a grouplet. A meteorite that matches no existing group is called ungrouped, written as "ung" in classifications such as "C2-ung" or "Iron, ungrouped".
Ungrouped meteorites are important because each may represent a parent body not otherwise sampled. Roughly one in seven iron meteorites is ungrouped, hinting that dozens more asteroids once had molten cores. Tagish Lake, which fell on a frozen lake in British Columbia in January 2000, is a famous carbonaceous chondrite classified as C2-ungrouped. Gebel Kamil, the nickel-rich iron that made Kamil crater in Egypt, is an ungrouped iron.
You cannot recognise an ungrouped meteorite by eye. It is a label that emerges only after careful laboratory work shows a specimen does not fit established groups. Related labels include "anomalous" ("an"), meaning a specimen belongs to a group but differs from it in some way.
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