Recommended classes in the Meteoritical Bulletin Database are assigned by the database editor. In most cases, this is based on the most recent classification that appears in either the Catalogue of Meteorites, MetBase, the US Antarctic Meteorite Newsletter, the Japanese Meteorite Newsletter, or the Meteoritical Bulletin. However, in a few cases it reflects differences of opinion about the proper way to classify the meteorite. The nomenclature used may also be modified by the editor to conform to an internally consistent classification scheme
The recommended classification Iron, IID-an means:
"An iron meteorite belonging to chemical group IID with anomalous properties."
The highlighted words are defined as follows:
iron meteorite: A meteorite that is dominantly composed of Fe-Ni metal and that crystallized from a melt.
anomalous: Designates meteorites that have been determined to be a member of a specific group, but have certain properties that are unusual or distinctive.
Find all meteorites of type: Iron, IID-an