CV chondrite
CV chondrites are carbonaceous chondrites with large chondrules and many white calcium-aluminium-rich inclusions.
The CV chondrites take their name from Vigarano, which fell in Italy in 1910. They have large chondrules, often around a millimetre across, set in a dark matrix, plus conspicuous white or pinkish calcium-aluminium-rich inclusions (CAIs) and amoeboid olivine aggregates. Almost all CV chondrites are petrologic type 3, meaning they were heated only mildly, though many were altered by fluids. Scientists split them into oxidised and reduced subgroups.
The best-known CV chondrite is Allende, which fell in Chihuahua, Mexico, on 8 February 1969. More than two tonnes of stones were collected, arriving just as laboratories were preparing to study Apollo Moon samples. Allende's CAIs became a cornerstone of cosmochemistry: they have been dated to about 4,567 million years, which is the standard reference for the age of the Solar System, and some contained traces of the decay products of short-lived isotopes such as aluminium-26.
A cut CV face is unmistakable: grey to black matrix speckled with round chondrules and irregular white CAIs, some several millimetres or more across. CVs are less crumbly than CI or CM chondrites.
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