Armalcolite is a titanium-rich mineral with the chemical formula (Mg,Fe²⁺)Ti₂O₅. It was first found at Tranquility Base on the Moon in 1969 and named for Armstrong, Aldrin and Collins, the three Apollo 11 astronauts. Together with tranquillityite and pyroxferroite, it is one of the three minerals which were discovered on the Moon. Armalcolite was then identified in various locations on Earth and synthesized in the laboratory. The synthesis requires low pressures, high temperatures and rapid quenching from about 1000 °C to the ambient temperature. Armalcolite breaks down to the mixture of magnesium-rich ilmenite and rutile at temperatures below 1000 °C, but the conversion slows down with cooling. Because of this quenching requirement, armalcolite is relatively rare and is usually found in association with ilmenite and rutile, among other minerals.