We present a new set of 200 kV high resolution electron microscopic images, including a through-focus series, of quasi-crystalline material in a specimen of rapidly quenched Al₆Mn in the three main projection directions of icosahedral point symmetry. Using the Penrose rhombohedra model of Duneau-Katz and Elser (obtained by orthogonal projection of a section of a 6-dimensional cube lattice into 3-dimensional space) and attributing the Al and Mn atoms only with the vertices of this tiling, a calculation of electron microscopic contrast has been made using the multislice technique. A comparison of the resulting simulated image contrast patterns with the images obtained by electron microscopy reveals good agreement for the image planes normal to the three main icosahedral symmetry axes.The morphology of certain quasicrystal domains bounded by straight planes is found to be related to the 5-fold axes of the icosahedral point symmetry. The pentagonal dodecahedron is therefore a possible ideal external shape of the faceted domain of Al-Mn quasicrystal in a f.c.c. Al matrix.