Basalt: Volcanic lava rock containing silicate minerals rich in magnesium and iron plus plagioclase. CI or chrondritic standard: elemental and isotopic abundances in the sun and in carbonaceous chrondrites

Basalt: Volcanic lava rock containing silicate minerals rich in magnesium and iron plus plagioclase. CI or chrondritic standard: elemental and isotopic abundances in the sun and in carbonaceous chrondrites are the same except in some very special details. Differentiation: creation of chemical differences in magma by processes that separate minerals from it, usually as a result of contrasting densities in a gravitational field. Gabbroic and noritic: Contains clinopyroxene or orthopyroxene, respectively, greater than ~10% by volume. Granulite: Rock composed of even-sized, interlocking mineral grains. Immiscible: Property of liquid phases that cannot dissolve completely in one another. Incompatible element: elements whose ions are incompatible with incorporation into the crystal lattices of common rock forming silicate minerals. Isochron age: radiometric age determined by extrapolation of the apparent ages of distinct phases or physical components in a rock. After Glossary of Geology, American Geological Institute. In the case of extinct parent radioisotopes, the isochron age relates to the time before the disappearance of measurable parent. Model age: radiometric age determined by analysis of the total proportion of parent and daughter isotopes in a given isotopic system. After Glossary of Geology, American Geological Institute. In the case of extinct parent radioisotopes, the model age relates to the time before the disappearance of measurable parent. Pressure release melting: denotes a process by which rocks very near to their initial melting point melt as a consequence of the removal of the pressure or weight of overlying rocks. Sometimes referred to as "decompression melting." Siderophile: Elements that tend be enriched in iron-rich metallic phases produced in nature.