Kalgoorlie gets its own mineral

A NEW mineral has been discovered by a Curtin WA School of Mines geochemist while combing through historical ore samples from the Kalgoorlie Super Pit.
Kalgoorlie gets its own mineral Kalgoorlie gets its own mineral Kalgoorlie gets its own mineral Kalgoorlie gets its own mineral Kalgoorlie gets its own mineral

Kalgoorlieite. Credit: Kirsten Rempel/Curtin University

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Dr Kirsten Rempel, from Curtin’s Department of Applied Geology, identified the microscopic, silvery coloured material in January 2015 when examining samples held in WASM’s museum at the Kalgoorlie campus.

After a year-long verification and classification process, the International Mineralogical Association formally declared the material a new mineral last month.

“I’ve decided to name it kalgoorlieite, after the type locality - it’s about time Kalgoorlie had its own mineral!” Rempel said.

The sample was collected from underground workings and has been sitting in the museum for years, described as “gold ore showing tellurides”.

Former WASM lecturer Dr Phillip Stothard initiated the examination of the samples, which was continued by Rempel after he left the project.

Curtin’s John de Laeter Centre provided high-magnification imaging, characterisation of the mineral’s crystal structure and chemical mapping, but the university also received external assistance.

The University of Western Australia supplied an electron microprobe to obtain a highly accurate chemical composition, while the Natural History Museum of London’s Dr Chris Stanley measured the amount of light reflected off the surface of the mineral – a property used to characterise and identify metallic minerals like this one.

The tiny sample was the largest amount of the mineral found so far and provided a unique opportunity to understand the origin of high grade ores taken from an area that was now just empty space in the middle of the Kalgoorlie Super Pit.

“This mineral, while only seen in very small grains so far, can provide important information about the genesis of the giant Golden Mile gold deposit, which is widely contested,” Rempel said.

Rempel said kalgoorlieite was a telluride mineral that was chemically related to the gold and silver telluride ores in the Kalgoorlie Super Pit. It had the general formula As2Te3, with As being the chemical symbol for arsenic.

“Kalgoorlieite contains only trace amounts of gold and silver, but it is closely associated with gold-silver telluride minerals such as sylvanite,” she said.

“The mineral will be added to the list of 5107 known minerals.

“Due to advances in analytical technology, the rate of new mineral discoveries is increasing.”

Rempel said it was rare to find a mineral with the simplicity of kalgoorlieite.

“The International Mineralogical Association receives more than 100 mineral proposals per year, with the majority of these being approved,” she said.

“However, most newly discovered minerals are very complex, with relatively small differences to existing minerals.”

The sample will eventually be on display in the WA Museum.