  In our article, we introduce and study lightlike hypersurfaces of a metallic
semi-Riemannian manifold. We examine some geometric properties of invariant
lightlike hypersurfaces. We show that the induced structure on an invariant
lightlike hypersurface is also metallic. We also define screen semi-invariant
lightlike hypersurfaces, investigate integrability conditions for the
distributions and give some examples.
