EN
We derive a structure model for icosahedral quasicrystals. The model is based on a statistical approach involving the concept of average unit cell. This approach enables limiting calculations to real space as opposed to higher-dimensional analysis involving to unphysical atomic surface modeling. We start with the three-dimensional Ammann tiling with its two rhombohedral prototiles. For monoatomic decoration of the lattice nodes the perfect agreement with the higher-dimensional description was recently shown. In this paper we discuss the shape of the average unit cell and the first attempts for decoration scheme.