We introduce and study procedures and constructions in the theory of the
joint spectral radius that are related to the spectral theory. In particular we
devlop the theory of the scattered radical. Among applications we find some
sufficient conditions of continuity of the spectrum and spectral radii of
various types, and prove that in GCR C*-algebras the joint spectral radius is
continuous on precompact subsets and coincides with the Berger-Wang radius