FIELD: chemistry. SUBSTANCE: invention relates to terahertz (THz) materials used in manufacture of terahertz optics. The terahertz crystal according to the invention is characterized by being made on the basis of single-phase solid solutions of the AgCl - AgBr - TlI system and containing chloride, silver bromide and monovalent thallium iodide at the following ratio of ingredients, wt. % : silver chloride - 5.0 to 10.0; silver bromide - 70.0 to 85.0; monovalent thallium iodide - 25.0 to 5.0. EFFECT: invention allows to produce crystals exhibiting optical transparency in the THz and mm ranges, as well as transparent in the visible and wide infrared spectral region, significantly more cost-efficient in growing and processing. 1 cl.