An achondrite is a type of stony meteorite whose precursor was of chondritic origin and experienced metamorphic and igneous processes. They have a planetary or differentiated asteroidal origin where the chondritic parent body reached a sufficient size that through heating due to radioactive decay of 26Al (aluminum isotope) and gravitational pressure allowed the parent body to differentiate into a core, mantle and crust that may also have experienced periods of volcanism. Some achondrites formed or were further processed though hypervelocity impacts on their parent body that could have been chondritic or achondritic in origin. As the name implies, the resulting rock lacks chondrules and, at a minimum, has lost its chondritic texture. Further processing may cause the resulting achondrite to also lose its chondritic composition. ... Expand

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