Iron doped lithium iodate α-LiIO3:Fe of hexagonal modification is investigated byholographic experiments in a geometry where an electrooptic contribution to thediagonal elements of the change of the dielectric permittivity tensor is forbiddenby symmetry. Anisotropic diffraction (electrooptically allowed) which we expected to observe in that geometry did not occur. Instead, isotropic diffraction (electrooptically forbidden) from light-induced gratings was found. To clarify its origin the properties of these gratings are studied as well as photo-induced transparency occurring in the ultraviolet. The experiments show that two types of gratings exist, one of them being an absorption grating. The second grating is attributed to originate from concentration changes which arise from the transport of ions triggeredby non-uniform illumination.