New England Meteoritical Services

Ordinary Chondrites

Ordinary chondrites are the most common type of stone meteorite, if "ordinary" and "common" are terms that can be applied to objects that have survived billions of years in outer space and a fiery plunge through our atmosphere at velocities measured in tens of kilometers per second.

Ordinary chondrites are further grouped by H, L and LL classifications, indicating iron content, and by the numbers 3-7, indicating the amount of change or metamorphism in the chondrules.

H chondrites have the highest iron content - 27 percent total iron by weight. They are commonly referred to as olivine-bronzite chondrites. L chondrites have a lower iron content, roughly 23 percent by weight and are referred to as olivine-hypersthene chondrites. LL chondrites represent "low iron" and "low metal" content. Sometimes referred to as amphoterites, they contain only 20 percent total iron.

The numbers following the H, L and LL classifications are petrologic grades indicating the degree of chondrule alteration by heating. Well defined, unaltered chondrules have a petrologic grade of 3 or 4. A higher number of 5 or 6 indicates an increased level of metamorphism making the chondrules less distinct.

Combining naming and classification conventions results in a specific specimen identification, such as the Saratov L4 olivine-hypersthene chondrite (13K GIF) from our Photo Gallery.

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