Deposition of impact-generated vapors in the lunar regolith

The composition and structure of the finest grain sizes in lunar soils are strongly influenced by impact-associated processes such as comminution, melting, and vaporization. These factors in turn exert a strong influence on the optical properties of the materials. The literature regarding the fractionations that accompany the evaporation of silicate materials during impacts is reviewed, the evidence for vapor deposits in the lunar samples is considered, our own efforts to characterize vapor deposits in lunar soils using electron microscopy is described, and the implications of vapor deposits on the optical properties of the lunar fines are discussed.