rock that contains 30 to 35 percent calcium-rich plagioclase feldspar (bytownite or anorthite), as well as augite, hypersthene, pigeonite, and olivine. The name was given (1863) by Gustav Rose to stony meteorites of this composition (see achondrite), but it has been extended to include similar intrusive igneous rocks (solidified from a liquid state). Occurrences of terrestrial origin are in Scotland, where it is common in the Tertiary ring complexes, and Carlingford, County Louth, Ire.