Samples of CVD ZnS from the United States, Germany, Israel, and China were evaluated using x-ray diffraction,
transmission and Raman spectroscopy, and biaxial flexure testing. Visible and near-infrared scattering, 6 μm
absorption, and ultraviolet cut-on edge varied substantially in tested materials. Transmission cut-on (ultraviolet edge)
blue-shifts with annealing and correlates with visible color but not the 6 μm absorption. Raman scattering for CVD
ZnS, presented here for the first time, was similar for all ZnS tested. Crystallographic hexagonality and texture was
determined and correlated qualitatively with optical scattering. All CVD ZnS tested with biaxial flexure exhibit similar
fracture strength values and Weibull moduli. This survey suggests that despite over 30 years of production as an
infrared window, the optical properties of CVD ZnS and their variability still defy easy explanation.