Lodestone is a magnetic mineral that is found in igneous and metamorphic rocks. It is a type of magnetite, which are minerals that possess a strong attraction to magnets.
All magnetite minerals display magnetism, but lodestone is the only one possessing north-south polarity. This property was noticed as early as the 4th century B.C. by the Chinese, who used primitive compasses made with lodestone. Another well-known property of lodestone is its ability to attract iron, which was first noted by the ancient Greeks in 600 B.C. This phenomenon was unexplained until scientist Peter Wasilewski demonstrated that lodestone may develop strong magnetic fields after being struck by lightning.