Potassium, Rubidium, Strontium, Barium, and Rare-Earth Concentrations in Lunar Rocks and Separated Phases

Concentrations of potassium, rubidium, strontium, barium, and rare-earth elements have been determined by mass spectrometric isotope dilution for eight Apollo 11 lunar samples and for some separated phases. Potassium and rubidium are at chondritic levels, strontium at 15 times, and barium and rare earths at 30 to 100 times chondritic levels. There are trace element similarities between the lunar samples and basaltic achondrites, terrestrial dredge basalts and the bulk earth. The trace element data appear to be consistent with these lunar samples being the result of limited partial fusion of some material similar to the brecciated eucrite meteorites.