Anorthosite

Anorthosite is a phaneritic, igneous rock characterized by a predominance of plagioclase feldspar. It was first discovered on the Moon at Hadley Rille during the Apollo 15 mission by astronaut Dave Scott, the rock dubbed "The Genesis Rock".

Anorthosite is commonly found in Highlands and Rilles, and is responsible for much of the lighter color composition of the moon; which is to differentiated by the basaltic/volcanic rocks of the Lunar Mares (Seas). It is of historical significance in solving one of the great mysteries of the formation of the moon. Apollo astronaut crews were requested to specifically search for anorthosite. Its presence indicates that the Moon was not a captured asteroid but was a product of a cataclysmic collision with the Earth, and as a result shares many chemical isotope properties as Earth rocks.