Investigations of submicron sized metal particles in glass coatings of lunar breccia 15286

Almost all the submicron metal particles in the glass coating of breccia 15286 are rounded and Contain two phases, metal and sulfide tEeS). The Ni content of the metal phase as determined by scanning transmission electron microscope X-ray analysis ranged from 9.4 to 15.5 tvt. The sulfide was nearly stoichiometric troilite containing up to 1.3 wt’ Ni. The close chemical and mi crostructural similarities between the coarse (>1 jzm) and the submicron sized metal indicate a com mon origin probabl as meteoritic debris. Metal-silicate melt experiments under controlled 10, indi cate that the metal particles may have formed from a fine dispersion of immiscible metal-sulfide droplets into an impact generated silicate melt.