Temora zircon gains increased scientific interest
31 August 2006
The value of zircon from the NSW town of Temora is once again being reflected within the international scientific community.
The Temora zircon, which are considered to be among the finest in the world for deriving the age of rocks, are being used as a benchmark in a study to evaluate analytical methods used by different dating laboratories in North America and Europe.
Geoscience Australia has been behind the discovery, identification and documentation of Temora zircon as well as distribution of the internationally recognised Temora Zircon standard. Zircon is a common mineral in igneous rocks, which, when formed, contain tiny traces of radioactive uranium locked inside its zircon crystals. This uranium then begins to decay in a process which produces small amounts of lead inside the zircon. This process occurs at a fixed rate which allows scientists to calculate the age of the rock by measuring the amount of lead inside the zircon crystals.
A world leader in geochronological investigations, Sandra Kamo, from the Jack Satterly Geochronology Laboratory at the University of Toronto, said Temora zircon was chosen for the project because of its consistency which resulted from its formation and relatively limited exposure to weathering.
The zircon's uncontaminated parent igneous rock has been exposed above ground for only about 20 years, resulting in very limited leaching of lead from the zircon within the rock.
Ms Kamo, who is part of the team evaluating the analytical methods, says the results from dating Temora zircon are so reproducible that the Temora standard helps determine whether individual laboratories are obtaining the right ages of rocks.
She says Temora zircon, along with the United States Geological Survey material, R33, is being used to evaluate both the methodology and the equipment used by different laboratories to establish why there are variations between results.
Ms Kamo is scheduled to visit Temora on Monday 4 September 2006 with a fellow scientist and colleague Dr. Lance Black from Geoscience Australia.
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