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 LL6/7 means:
"An ordinary chondrite from the LL group that is either petrologic type 6 or type 7."
The highlighted words are defined as follows:
ordinary chondrite: A major class of chondrites, distinguished by sub-solar Mg/Si and refractory/Si ratios, oxygen isotope compositions that plot above the terrestrial fractionation line, and a large volume percentage of chondrules, with only 10-15 vol% fine-grained matrix.
LL group: The low-iron, low metal (LL) chemical group of ordinary chondrites, distinguished by their low siderophile element content, fairly large chondrules (~0.9 mm), and oxygen isotope compositions that are further above the terrestrial fractionation line than those of other ordinary chondrites. .
type 6: Designates chondrites that have been metamorphosed under conditions sufficient to homogenize all mineral compositions, convert all low-Ca pyroxene to orthopyroxene, coarsen secondary phases such as feldspar to sizes ≥50 µm, and obliterate many chondrule outlines; no melting has occurred.
type 7: Designates chondrites which have been metamorphosed to nearly the point of melting. Minerals are equilibrated and chondrules are indistinct or absent. This term is not used consistently or widely accepted in the literature.
Find all meteorites of type: LL6/7