The Iron Sand is the name of the weapon used by the Third Kazekage, in combination with his special ability to convert chakra into magnetic forces. When imitating the sand techniques of Shukaku's host, he used iron powder instead, thanks to his special magnetic powers. He often moulded the iron powder into weapons and used them as his main mode of attack. The Iron Sand can also clot up the joints of puppets, making them unusable in battle as long as the Third Kazekage's magnetic field is in effect. Chiyo referred to this technique as "the most feared weapon in the history of Sunagakure". After Sasori turned the Third Kazekage into a human puppet, he too became a user of the Iron Sand.
When Sasori made the Kazekage into a puppet he drenched the sand in poison, making it more lethal in battle.
Magnetite, the main component of Iron Sand, is about 2 times denser than silica, which is the main component of sand, while gold is about 3.7 times denser than magnetite.