Anorthosite is a coarse grained, intrusive, igneous rock. It is considered intrusive because it was formed by the crystallization of magma as it pushed its way up from deep with the earth, filling in any available spaces that it could find. It was found on the surface of the Moon, and has been an important factor for the examinations and investigations of Mars, Venus, and meteorites.
It appears typically in a grey or bluish color, though the individual plagioclase crystals can add highlights of black, white, blue, or grey, giving it a type of iridescence.
Origin: CO