New data for the lunar 20 core and a survey of published chemical data

Lunar core samples were analyzed using a spark source mass spectrometer. The analytical results for the four zones of the Lunar 20 core suggest that the core is nonuniform with depth. The higher concentrations of Ce, Sc, Sc, Ba, La, Co, Sr, and Zr in zone 2001 may be connected with the presence in this zone of a basaltic rock type seldom seen in the other zones. That is, about half of the basaltic fragments in the large size fractions in zone 2001 are of a specific porphyritic breccia-like type. Anorthositic fragments containing a notable amount of metallic iron are basically limited to zone 2004 and probably explain the lower concentrations of Ce, Rb, Ba, La, and perhaps Co in this zone. The high concentrations of Ag and Ce found previously are confirmed. Although Ag is at nearly the same concentration in all four zones of the core, Cd in the core is the result of local enrichment. In particular, in zone 2004 the concentration of Cd may be as high as 10 ppm in a sample size of 0.01 mg.