Magnetite is originally contained in rock that has hardened from lava ejected from volcanoes. This rock is exposed to air and water for a long, long time. The magnetite in the rock is broken up and carried away by the flow of rivers, ocean waves, wind, and other currents. Before long, many of them are gathered at places like sandy beaches. This is how iron sand is formed.

Magnetite is a very common mineral that is commonly found in igneous rocks. This is then crushed into small pieces to form iron sand.