This invention is directed to the production of transparent glasses exhibiting excellent transmission far into the infrared region of the electromagnetic radiation spectrum, said glasses consisting essentially, expressed in terms of mole percent on the sulfide basis, of 55-95% GeS.sub.2, 2-40% As.sub.2 S.sub.3, 0.01-20% R.sub.2 S.sub.3, wherein R is at least one trivalent network forming cation selected from the group consisting of gallium and indium, 0-10% MS.sub.x, wherein M is at least one modifying cation selected from the group consisting of aluminum, barium, cadmium, calcium, lead, lithium, mercury, potassium, silver, sodium, strontium, thallium, tin, yttrium, and a rare earth metal of the lanthanide series, 0-20% total of at least one halide selected from the group consisting of chloride and fluoride, 0-5% total selenide, and wherein the sulfur and/or selenium content can vary between 85-125% of the stoichiometric value. The difference between the temperature of the onset of crystallization and the transition temperature of the glasses is at least 150.degree. C. and commonly will be greater than 200.degree. C.