World’s oldest rock, newest technology to be on display

The world’s oldest terrestrial material, a tiny grain of zircon crystal whose study radically altered scientific views of the early Earth, will be on brief public display Saturday, April 9, at the Geology Museum.

Measuring little more than two human hairs in diameter, the tiny grain of zircon crystal was found in the Jack Hills region of Australia and is estimated at 4.4 billion years old. It was dated by Simon Wilde, a professor in the School of Applied Geology at Curtin University of Technology in Perth, Western Australia. Wilde will deliver a free public lecture on the geology and zirconology of the Jack Hills region of Australia at 3:30 p.m. on Friday, April 8, in AB20 Weeks Hall, 1215 W. Dayton St.

A 2001 analysis of Wilde’s zircon by geochemist John Valley provided evidence that the early Earth was much cooler than previously believed, and that water and oceans, key preconditions for life, formed much earlier than scientists had previously imagined. Subsequent analysis by graduate student Aaron Cavosie has supported these conclusions.

Valley’s analysis of the Jack Hills zircon was conducted, in part, with the aid of a device known as an ion microprobe, a machine capable of extracting chemical and isotope ratios from very small samples. In the case of the Jack Hills zircon crystal, Valley’s work showed that the mineral could only have formed as the result of a low temperature environment on Earth’s surface.

At the time, Valley and his students needed to travel to Scotland to use one of the few ion microprobes available. UW–Madison now is installing its own ion microprobe, and the $3 million device will be available for public viewing concurrent with the zircon display from 10 a.m.-3 p.m. on Saturday, April 9, in Weeks Hall. The new ion microprobe will be in the lobby adjacent to the Geology Museum. All events are free and open to the public.

Another event celebrating the ancient rock, “The Rock Concert,” is commissioned by the museum’s Stony Muse project, a cross-disciplinary program that looks at various aspects of geology/geophysics and the arts and humanities. Jazz Passengers, a band that has toured with famous rock artists such as Elvis Costello and Jeff Buckley, will perform the concert at 8 p.m. on Saturday, April 9, in the Great Hall of Memorial Union, 800 Langdon St. Tickets, which are free but required, are available from Joe Skulan, director of the Geology Museum, (608) 265-4274 or jlskulan@geology.wisc.edu.