How are the atoms arranged in iron?

Iron exists in three configurations, or allotropes, at standard pressures. Each of these allotropes has a unique arrangement of atoms that influences the properties of the iron mass.

A common allotrope of iron is alpha iron, which consists of iron atoms arranged in a cubical box shape with one atom of iron contained inside the structure. Another allotrope, gamma iron, is also roughly held in a box shape, but with extra iron atoms suspended exterior to the sides of the box. The atoms in delta iron also form a cube.

At extremely high pressures, iron can be reconfigured into epsilon iron, or hexaferrum, which is a close-packed hexagonal allotrope.