The experimental data on the electrical, thermal, and optical properties of high-boron compounds and modifications of boron--refractory crystals distinguished by specific and complicated structure--are reviewed. It is shown that depending on the complexity of the crystalline structure the properties of the materials transform, systematically approaching the properties characteristic of amorphous semiconductors; a new class of materials is thus identified--quasiamorphous semiconductors. In the limiting case of the most complicated structures, they can be regarded as natural structural models of amorphous semiconductors.