Clair Patterson
The geochemist who used lead from meteorites to measure the age of the Earth, 4.55 billion years, in 1956.
Key facts
- Born
- 1922
- Died
- 1995
- Nationality
- American
- Field
- Geochemist
Clair Cameron Patterson grew up in Iowa and worked on the wartime atomic bomb project before studying for his doctorate at the University of Chicago. His task, set by the chemist Harrison Brown, was to measure the age of the Earth from the decay of uranium into lead.
The idea was simple but the measurement was extraordinarily hard. Lead was everywhere in the laboratory, in dust, glassware and the air, and it swamped the tiny amounts in his samples. Patterson built one of the first ultra-clean laboratories, scrubbing everything and filtering the air, to keep stray lead out.
He needed a sample of lead from the beginning of the Solar System, and found it in meteorites. The troilite in the Canyon Diablo iron contains lead but almost no uranium, so its lead has barely changed since it formed. Comparing it with lead in stony meteorites and on Earth, in 1956 Patterson calculated that the Earth and the meteorites are about 4.55 billion years old. Modern measurements agree.
His clean-room work revealed something alarming: the modern world was full of lead from petrol and paint. Patterson spent the rest of his life campaigning against lead pollution, despite fierce opposition from industry. His work helped lead to the removal of lead from petrol, one of the great public health achievements of the twentieth century.