A Chemically Vapor Deposited (CVD) material, ZnS (regular) has good imaging quality over the 8-12µm band. It also transmits in the 3-5µm band, but with higher absorption and scatter. The material exhibits high strength and hardness, and good resistance to hostile environments. The ZnS regular is 50% harder than ZnS multi-spectral grade and twice and hard as ZnSe. ZnS regular does not transmit well in the visible spectral region. It has the relatively low cost of about 2/3 the price of ZnS, multi-spectral grade or ZnSe. Zinc Sulfide is mainly used for windows and lenses in the 8µm to 12µm range. The reflective index is near 2.2. Zinc Sulfide is particularly strong and can be used for infrared windows in high speed aircraft and vacuum applications.