However, the acoustopolarigrams of samples h001, h003, h007, h009, h010, h023 and h025 show the presence of the symmetry element projections on all three faces and with a more rigorous approach they should be assigned near to the orthorhombic (R in Table) symmetry type (Gorbatsevich, 2009).

The acoustopolariscopy method allows one to determine spatial orientation of the symmetry element projections, to distinguish the quasi-transverse-isotropic elastic symmetry type from the orthorhombic type.

This method solves the problem of experimental determination of spatial orientation, the type and number of symmetry elements in anisotropic heterogeneous media.

Sharp minimums of the amplitudes on the VC acoustopolarigrams allow one to determine the directions of elastic symmetry elements (axes and planes).

One can draw straight lines connecting the minimal amplitude of the signal passing through the sample almost everywhere on the VC acoustopolarigrams and thus determine the spatial location of the projections of elastic symmetry elements.

The presence of the symmetry elements on the acoustopolarigrams of samples 24996s, 28184s point to near orthorhombic symmetry type, while those of samples 30020, 24947--to transversal-isotropic.

Earlier a similar effect of depolarization of linearly polarized light waves as they propagate through accidentally heterogeneous media or media composed of anisotropic materials (layers) with differently oriented symmetry elements, was registered in optics (Shurkliff, 1962).