Geology of the Moon the Moon. Lunar rocks are in large part made of the same common rock forming minerals as found on Earth, such as olivine, pyroxene, and plagioclase feldspar (anorthosite). Plagioclase feldspar is mostly found in the lunar crust, whereas pyroxene and olivine are typically seen in the lunar mantle. The mineral ilmenite is highly abundant in some mare basalts, and a new mineral named armalcolite (named for "Arm"strong, "Al"drin, and "Col"lins, the three members of the Apollo 11 crew) was first discovered in the lunar samples. The maria are composed predominantly of basalt, whereas the highland regions are iron-poor and composed
Crust (geology) collided and stuck, gradually growing into a planet. This process generated an enormous amount of heat, which caused early Earth to melt completely. As planetary accretion slowed, Earth began to cool, forming its first crust, called a primary or primordial crust. This crust was likely repeatedly destroyed by large impacts, then reformed from the magma ocean left by the impact. None of Earth's primary crust has survived to today; all was destroyed by erosion, impacts, and plate tectonics over the past several billion years. Since then, Earth has been forming secondary and tertiary crust. Secondary crust forms at mid-ocean spreading