Fred Frey dropped into my office in 1961 to talk about thesis research. Fred was a chemical engineer who, after a year's experience in industry, decided to get a Ph.D. in chemistry. After we talked, Fred decided that a combination of physical chemistry, radiochemistry, and geochemistry could interest him for the next few years. I guess he was right, since he's still at it. He defended his dissertation in 1966 and joined the faculty of Earth, Atmospheric, and Planetary Sciences at MIT [the Massachusetts Institute of Technology], and he is still there.
For his thesis, Fred chose to survey mafic and ultramafic rocks for their rare earth element (REE) concentrations. Back then, we did not know what typical REE relative abundances were in Earth's most voluminous intrusive and extrusive rocks—peridotites and basalts. Would basalts, like shales, turn out to be relatively enriched in the lighter REE, compared to the distribution in chondrites? Would peridotites have relative abundances like those of chondrites, or would they be depleted in light REE in complement to crustal materials?