Types of Moon Rock

Lunar Meteorites

• Lunar meteorites are rocks that have been ejected from the moon by meteoroids hitting the moon's surface. Meteoroids hit the moon every day, according to Washington University in St. Louis, but lunar meteorites are rarely found on Earth. Most of the lunar meteorites found have been breccias. Scientists think their chemical compositions may be more indicative of typical moon rocks than samples collected on the Luna and Apollo missions, according to Washington University in St. Louis. This is because the missions have all landed in a small area on the moon's near side, and have often concentrated on geologically "interesting" areas that are thought to be atypical of the moon as a whole.

Breccias

• Breccias are composite rocks formed from other rock types. They are the most common rocks on the moon's surface, according to NASA. Most lunar breccias are the aggregates of debris generated by meteorite bombardment in the ancient lunar highlands, according to NASA. Some of the samples collected by the Apollo missions have been dated 3.9 billion years old.

Basalts

• Basalts are volcanic rocks formed by rapidly cooling lava at a planetary body's surface. On Earth they are commonly found in areas of high volcanic activity. The landing sites for Apollo missions were limited to mildly-cratered, flat spots, which generally turned out to be lava flows, according to NASA. This is why many of the rock samples collected were basalts. Most of the basalts collected were rich in iron and titanium.

Anorthosites

• Anorthosites are light igneous rocks composed almost entirely of plagioclase feldspar. They are the oldest rocks on the moon and appear to have formed when feldspar crystallized and floated to the top of a global magma ocean that surrounded the moon soon after it formed, according to Planetary Science Research Discoveries.