Anorthosites, igneous rocks rich in plagioclase feldspar, are common on the Earth, Moon, and possibly other planets. Though anorthosites are usually not considered to be strongly magnetic, researchers note that their magnetic properties could be useful in investigating mineral deposits in addition to magnetic anomalies on other planets, particularly Mars. Through investigations of three ancient anorthosite bodies in Norway, the authors find that two anorthosites have large natural remanent magnetization signatures, indicating that they contain strong signatures of the Earth’s magnetic field direction that was present when the rocks crystallized roughly 1 billion years ago.