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 CH/CBb means:
"A carbonaceous chondrite that is transitional between the CH group and the b-subgroup of the CB group"
The highlighted words are defined as follows:
carbonaceous chondrite: A major class of chondrites that mostly have Mg/Si ratios near the solar value and oxygen isotope compositions that plot below the terrestrial fractionation line.
CH group: The high-metal (CH) chemical group of carbonaceous chondrites, similar to Allan Hills 85085; CH chondrites have tiny chondrules and refractory inclusions (~0.02 mm), abundant metal (~20 vol%), no fine-grained matrix except as xenolithic clasts, and rare sulfides consistent with overall low volatile element contents. It is uncertain whether members of the group are true chondrites, as they may have formed slightly later in solar system history.
CB group: The Bencubbin-like (CB) association of carbonaceous chondrites. The CBa subgroup is distinguished by cm-sized chondrule-like objects, abundant metal (>half the volume), no fine-grained matrix, and almost no refractory inclusions. The CBb subgroup contains small chondrules (0.2 - 1 mm), abundant metal (~70 vol%), and some refractory inclusions. It is uncertain whether any or all CB meteorites are true chondrites, as they may have formed slightly later in solar system history.
Find all meteorites of type: CH/CBb