John Wasson
The UCLA chemist who sorted iron meteorites into chemical groups using nickel, gallium, germanium and iridium.
Key facts
- Born
- 1934
- Died
- 2020
- Nationality
- American
- Field
- Cosmochemist
John Taylor Wasson spent his long career at the University of California, Los Angeles, where he looked after part of the university's large meteorite collection and ran a laboratory for analysing iron meteorites.
Before the 1960s, iron meteorites were sorted mainly by the patterns seen in etched slices. Wasson used a sensitive method called neutron activation analysis to measure trace elements, especially gallium, germanium and iridium, alongside nickel. When he plotted the results for hundreds of irons, they fell into distinct clusters. Each cluster, or chemical group, was given a code such as IAB, IIAB, IIIAB or IVA.
Most of these groups are thought to be pieces of the metal cores of separate asteroids. The way the trace elements vary within a group shows how the molten core crystallised as it cooled, like a great frozen pool of metal. Using this chemistry, Wasson and his colleagues argued that iron meteorites sample the cores of dozens of different early asteroids.
Wasson also wrote textbooks and worked on chondrites and chondrules. He measured the irons in the UCLA collection for over fifty years. In 2010 a new mineral, a sulphide of titanium found in an Antarctic meteorite, was named wassonite in his honour.