Although ordinary X-ray diffraction is 'blind' to the arrangement of the spins, it has become possible to use a special form of X-ray diffraction to study magnetic structure. If a wavelength is selected that is close to an absorption edge of one of elements contained in the materials the scattering becomes anomalous and this component to the scattering is (somewhat) sensitive to the non-spherical shape of the outer electrons of an atom with an unpaired spin. This means that this type of anomalous X-ray diffraction does contain information of the desired type.