Iron Sand ( 砂鉄, Satetsu, Literally meaning: Sand Iron) is the most feared weapon in the history of Sunagakure, which was developed by the  Third Kazekage.
After studying the sand manipulation abilities of
Shukaku's jinchūriki, the Third Kazekage was able to imitated this ability using iron powder instead of sand, and his special magnetic powers. He often moulded the iron powder into weapons and used them as his part of his main fighting style.
When used in sufficient quantities, this iron powder can be equipped into a diverse number of ways, in which
Sasori took full advantage of through the use of his puppet of the Third Kazekage. In order to create useful techniques ranging from large structures to bullet-like particles and multiple striking branches.
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, even bypassing a  Chakra Shield.
Utilised Techniques Edit
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.
Naruto chapter 268, page 9 ↑
Naruto chapter 268, page 6