Magnetite - This rare mineral is naturally magnetic.

Magnetite is a naturally occurring iron oxide mineral (Fe₃O₄) known for its strong magnetic properties. It is one of the most magnetic minerals found in nature and occurs in igneous, metamorphic, and sedimentary rocks. While magnetite can be processed for industrial uses such as iron ore, only certain pieces of magnetite can become naturally magnetized. Unlike lodestone, which is magnetite that has acquired a permanent magnetic charge, most magnetite is not magnetized.