In the present work, a large glass-forming region was found in the novel GeS2-Sb2S3-PbS system, in which up to 58 at.% PbS could be incorporated without deteriorating the thermal and physical properties of glasses. Infrared (IR) transmitting glass ceramics with a large amount of small-sized crystals ( < 100 nm) were then produced by choosing sub-stable compositions and annealing at fairly low temperatures (15 degrees-30 degrees C above T-g) for long durations (up to 100 h). Crystals were identified by X-ray diffraction as Pb2GeS4, PbGeS3, PbS, PbSb2S4, etc., depending on base glass compositions. Compared with base glasses, glass ceramics showed much improved thermal shock resistance and fracture toughness, making them good candidate materials for IR optics.