We have studied theoretically and by numerical simulations the topolog
ical properties of Voronoi tessellations of slightly perturbed fee and
hcp lattices. The number f of faces of a cell can go from 12 to 18 wi
th a mean value [f] = 14 very different from the value 12 in the non-p
erturbed lattices. A face can have 4, 5 or 6 sides; we give the percen
tages of each type of face both in the cells with given values of f an
d in the whole tessellation. The study of the topological correlations
between neighbouring cells shows that Aboav-Weaire's law is valid.