Petrographic province

A petrographic province is a geological region within which the igneous rocks reveal a relationship (so-called consanguinity) in chemical composition, which may be referred to a community of origin. This relationship may be chemically a close one, but the rocks have widely varying mineralogical composition, or the kinship may be restricted to one or more of the chemical components in the rocks.
Etymology.
Petrography derives from "petra" (), meaning rock, and "graphein" (), to write.