  We study the secular instability of magnetized differentially rotating
radiative zones taking account of viscosity and magnetic and thermal
diffusivities. The considered instability generalizes the well-known
Goldreich-Schubert-Fricke instability for the case of a sufficiently strong
magnetic field. In magnetized stars, instability can lead to a formation of
non-spherical unstable zones where weak turbulence mixes the material between
the surface and interiors. Such unstable zones can manifest themselves by a
non-spherical distribution of abundance anormalies on the stellar surface.
