Four billion year old microdiamond inclusions in Jack Hills zircon have been discovered through a collaborative research effort involving researchers from Curtin University of Technology’s Department of Applied Geology in the Western Australian School of Mines and the University of Munster’s Institute of Mineralogy in Germany.

These findings include the oldest known diamonds found in terrestrial rocks and introduce a new dimension to the debate on the origin of zircons in Jack Hills and the evolution of the early Earth.

These research findings are discussed in a paper published in the 23 August 2007 issue of the prestigious international scientific journal Nature.

Dr Alexander Nemchin from Curtin’s Department of Applied Geology and one of the researchers in this project expressed excitement over the findings.

“This project got its start in 1983 when extremely old zircon was found in rock samples obtained on a Curtin field trip to Jack Hills. Finding the world’s oldest diamonds more than 20 years later in these rocks was an unexpected but significant discovery,” Dr Nemchin said.

“This is now the first step in what promises to be a very rich area of research and we look forward to taking the research to the next level.”

Professors Simon Wilde and Robert Pidegon, also from Curtin’s Department of Applied Geology, pioneered the project in 1983 and were behind the original discovery of extremely old detrital zircon in the Jack Hills rock samples.

These detrital zircons are the oldest identified fragments of the Earth’s crust and are unique in preserving information on the earliest evolution of the Earth.

Commenting on the microdiamond discovery in the Jack Hills detrital zircons, Professor Pidgeon highlighted the significance of these findings.

“Although, many questions remain regarding the origin of the diamonds and their incorporation in the Jack Hills zircon, these findings place new constraints on ideas or models of the earliest crustal evolution on the Earth,” Professor Pidgeon said.

The researchers investigated mineral inclusions in 1,000 randomly chosen zircon grains from the Jack Hills rock samples using a RAMAN microprobe. Ages of these zircon grains were determined using a sensitive high-resolution ion microprobe (SHRIMP II) hosted by the John de Laeter Centre of Mass Spectrometry at Curtin.