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 Ureilite-an means:
"An achondrite belonging to the ureilite group with anomalous properties."
The highlighted words are defined as follows:
achondrite: A stony meteorite that lacks chondrules and originated on a differentiated parent body.
ureilite: Ureilites, named after the Novo-Urei, Russia, fall of 1886, are ultramafic achondrites that contain interstitial carbon as graphite or diamond. The majority consist of olivine + uninverted pigeonite. In a few, the pyroxene is augite and/or orthopyroxene instead. In addition, about 10% of ureilites are polymict breccias, containing a few percent of feldspathic material in addition to typical ureilitic components.
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: Ureilite-an