William Compston FAA FTSE FRS, was born in Western Australia in 1931. As a child he lived with his parents at his father’s butcher’s shop in Perth. After his father died in 1943 the shop was sold and the family went to visit relatives in Melbourne, becoming trapped there by wartime restrictions on travel to Perth. While in Melbourne Bill was introduced to geology by one of his brothers, who had a science degree in Geology.

Returning to WA, Bill studied for a BSc at the University of Western Australia (UWA), including Geology as one of his subjects. Through his wife Elizabeth, who was in his year at University and also studying Geology, he joined in with a group of people who had been to Perth Modern School. Spurred on by their urge to do well, he became immersed in discussions of mutual problems in subjects such as physics and mathematics.

Bill subsequently completed a PhD at UWA, supervised by Peter Jeffery, focusing on the isotopic composition of carbon in rocks. Work under Jeffery introduced him to the techniques of isotopic analysis as well as the solving of practical problems, such as repairing faulty electronics.

The award of a Fulbright Fellowship took Bill to the California Institute of Technology for a year, where he continued his work on stable isotopes, this time with Sam Epstein, using the isotopic composition of oxygen to infer the temperature at which fossil shells had grown. While in the USA he spent three months at the Carnegie Institute Department of Terrestrial Magnetism (DTM), where he was instructed by leading scientists such as Tom Aldrich and George Wetherill in the techniques for dating rocks using the U-Pb, Rb-Sr and K-Ar decay schemes.

Bill returned to UWA as a lecturer in Physics. There, working with Peter Jeffery, he used what he had learned at the DTM to set up the technology for Rb-Sr dating, starting with minerals from local rocks. When the ages measured proved inconsistent with the geology, he decided to analyse whole rocks (the first to do so), showing for the first time that while minerals can gain or lose radiogenic Sr, whole rocks can remain closed isotopic systems. Proving the presence of Archaean rocks in Western Australia and two letters in Nature were the result.

In the early 1960s Bill was persuaded by Prof. Jaeger to join the Department of Geophysics at the ANU. There, in collaboration with the Bureau of Mineral Resources (BMR) he set up the laboratory and mass spectrometer necessary for Rb-Sr dating and started on a program of dating Australian rocks, the ages of which were little known at the time.

Following the return of the first lunar samples by the Apollo 11 astronauts in 1969, Bill was one of the few researchers chosen by NASA to date the rocks, whilst Ted Ringwood and Ross Taylor, also at RSES, worked on other aspects of their geochemistry. Bill’s results compared well with those from the best of the international labs, giving him increased confidence in the procedures he had established at the ANU.

At the first lunar science conference, Bill heard of dating that had been attempted using U-Pb extracted from samples on a very small scale, in situ, using an ion microprobe. The process was analogous to electron probe analysis, which was at an early stage of development at the time but, because a focused ion beam removed material from the sample surface, had the advantage that it was possible to measure isotopic compositions. The results were compromised by the presence of molecular interferences, setting Bill thinking about how these could be avoided.

Working with Steve Clement, who had designed, for his PhD, the high sensitivity mass spectrometer used for dating the lunar samples, Bill decided that RSES should build an ion microprobe for geological work. Modelling by Clement showed that, to achieve the necessary mass resolution and high sensitivity required for trace element isotopic analysis, the instrument would need to be three times the size of existing mass spectrometers. The undertaking was a huge risk (an expert committee advised against it), made possible by block funding to RSES and the strong support of the then Director, Anton Hales. Funding for the construction was contributed by several of the RSES research groups, making the new instrument a whole-of-School enterprise.

Clement designed the ion optics, and construction of SHRIMP began in 1974, much of the hardware and electronics built in-house in the RSES workshops. By 1979 the instrument was under test using Sr and a hot filament ion source. By 1980 a duoplasmatron oxygen primary ion source was fitted and in 1981 experiments were started, jointly with Ian Williams, dating U-Pb in zircon. The first results were announced in the 1981 RSES Annual Report.

SHRIMP revolutionised U-Pb geochronology, and until the development of the LA-ICPMS many years later, was the only method of dating minerals accurately in situ on a 20 µm scale. International visitors flocked to the lab, building links between Bill (and RSES), and the leading geochronology labs throughout the world. Multiple successes followed, chief amongst them the dating of lunar zircon, refinement of the geological time scale, the discovery in WA, by PhD student Derek Froude, of the first terrestrial zircons older than 4 Ga, the discovery at Jack Hills, WA, with Bob Pidgeon, of detrital zircon nearly 4.4 Ga old, and the dating, by Samuel Bowring and Ian Williams, of the first igneous rocks > 4.0 Ga.

In an interview conducted by the Australian Academy of Science in 2005, Bill reflected on the unique opportunities that working at RSES had afforded to him, the importance of block funding in supporting risky scientific endeavours, and the essential support provided by the RSES mechanical and electrical workshops. SHRIMP went on to be a commercial success, the last of 20 instruments built by the ANU installed in China in 2023.

William Compston FAA FTSE FRS died peacefully, in the presence of family members, on Friday May 16, aged 94 years.

Summarized by Ian Williams, RSES.