Anorthite

: During the early cooling of the Moon, anorthite crystals were less dense than the surrounding basaltic magma. They floated to the surface, forming a thick crust of anorthosite (a rock composed of 90–100% plagioclase).

Anorthite is characterized by a three-dimensional network structure of SiO4cap S i cap O sub 4 AlO4cap A l cap O sub 4 tetrahedra. : anorthite

: On Earth, pure anorthite is restricted primarily to basic and ultrabasic igneous rocks like gabbro, picrite, or specialized formations such as the Adirondack Mountains . : During the early cooling of the Moon,