A NASA sounding rocket launched from Wallops Island, VA (37.84 N, 75.48 W) on 1 July 2003 at 2:50 EST made the first in situ measurement of the relative concentrations of Fe+, Mg+, O2+, and NO+ within a nighttime intermediate layer below 140 km altitude. Ion composition measurements were made from 80--220 km altitude and included observations of three separate regions having high concentrations of metallic ions: the intermediate layer at 118 km, a sporadic-E layer at 105 km, and a third layer above 160 km altitude. These observations demonstrate that metallic ions may be a significant source of ionization in the nighttime E and F region ionosphere at midlatitudes.