Magnetite

A mineral and one of the main iron ores, an iron oxide that is ferrimagnetic: attracted to a magnet and able to be magnetized into a permanent magnet itself. Apart from extremely rare native iron deposits it is the most magnetic of all naturally occurring minerals on Earth, and naturally magnetized pieces called lodestone are how ancient peoples first discovered magnetism. Its locked-in magnetization is also the record paleomagnetism reads. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/