This paper reports on the results of an investigation into the influence of Sb₂S₃ dopants on the glass-forming ability, heat resistance, softening temperature, density, refractive index, transparent region, and impurity optical absorption of glasses of the composition 0.16GaS₂ • 0.84GeS₂. The data obtained indicate that glasses in the Ga₄Ge₂₁S₅₀-Sb₂S ₃ system with a high Sb₂S₃ content are of interest as materials for use in fiber optics.