FIELD: chemistry. SUBSTANCE: invention relates to terahertz (THz) materials transparent in the visible, infrared (0.5 to 50.0 microns), terahertz and millimeter ranges – 0.05 to 10.0 THz, corresponding with wavelengths of 6000.0 to 30.0 microns. The terahertz crystal according to the invention is characterized by being based on silver chloride and bromide and additionally containing a solid monovalent thallium bromide-iodide (TlBr0.46I0.54) solution at the following ratio of components, wt. % : silver chloride - 5.0 to 20.0; silver bromide - 60.0 to 75.0; solid solution (TlBr0.46I0.54) - 35.0 to 5.0. EFFECT: invention allows to produce crystals with non-hygroscopic and highly plastic properties, transparent in the terahertz, millimeter, visible and infrared spectral ranges, wherein in the range between 7.0 and 10.0 THz the crystals exhibit optical transparency of up to 78% corresponding with theoretical transmission. 1 cl.