As early as 600 B.C. the Greeks knew that a certain form of iron ore, now known as magnetite or lodestone, had the property of attracting small pieces of iron. Later, during the Middle Ages, crude navigational compasses were made by attaching pieces of lodestone to wooden splints floating on bowls of water. These splints always come to rest pointing in a N-S direction, and were the forerunners of the modern aircraft and ship compasses.
The word lodestone is derived from an old English word meaning way, and refers to the directional property of the stone mentioned above. Chemically, it consists of iron oxide having the formula Fe3 O4. The word magnetism is derived from Magnesia, the place where magnetic iron ore was first discovered.