  Crystallization of dense matter in neutron star crusts and white dwarf cores
may be similar to epitaxial crystal growth in terrestrial laboratories. However
in stellar crystals, the spacing between horizontal planes has to gradually
increase with the outward movement of the crystallization front, tracing
decrease of the electron density. This process produces Coulomb crystals with
stretched rather than cubic elementary cells. We extend the analysis of the
elastic and breaking properties of such crystals to the face-centered (fc)
lattice. Shear deformations orthogonal to the stretch direction have been
studied for 22 crystallographic shear planes. A common property for all these
planes is a reduction and eventual nulling of the breaking shear strain with
deviation from the unstretched configuration. The effective shear moduli for
deformations orthogonal to the stretch direction have been calculated. It is
possible that the epitaxial crystallization in compact stars results in a
formation of large-scale crystallites or, at least, in growth of the whole
crystallization front perpendicular to particular crystallographic planes. For
fc structure growth orthogonal to the $\{111\}$ planes, we expect that, at any
density, $\sim 5\%$ ($\sim 0.5\%$) of crystallite height is occupied by layers
one (two) orders of magnitude weaker than the bulk of the crystallite. This may
be important for realistic modeling of crustquakes on neutron stars.
