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 CK4/5 means:
"A carbonaceous chondrite of the CK group that is either petrologic type 4 or type 5."
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.
CK group: The Karoonda (CK) chemical group of carbonaceous chondrites, distinguished by abundant fine-grained matrix (~75 vol%), mm-sized chondrules that lack igneous rims, relatively few refractory inclusions, and a high degree of oxidation; most CK chondrites have been metamorphosed to type 4 or higher.
type 4: Designates chondrites that are characterized by abundant chondrules, and have been metamorphosed under conditions sufficient to homogenize olivine compositions and recrystallize fine-grained matrix. Some of the low-Ca pyroxene grains may be monoclinic and exhibit polysynthetic twinning. Primary igneous chondrule glass is absent.
type 5: Designates chondrites that have been metamorphosed under conditions sufficient to homogenize olivine and pyroxene, convert all low-Ca pyroxene to orthopyroxene, cause the growth of various secondary minerals, and blur chondrule outlines.
Find all meteorites of type: CK4/5