Australian scientists have uncovered a a rare volcanic rock in Antarctica that carries diamonds to the Earth's surface.

The rock formations, called kimberlites, had been discovered on every continent except Antarctica until now.

However, mining is not an option in the protected area, so the precious gems will stay under the ice for now.

The Australian National University's Greg Yaxley says although the rocks are home to precious gems, they are not always pretty.

"From the point of view of a geologist they're fairly ugly rocks because they're usually very altered, so the primary original minerality is often broken down to minerals like serpentine and calcite and so forth," he said.

Professor Dima Kamenetsky from the University of Tasmania was part of the team that identified the rock.

It was a lucky find during a hunt for other types of rock in the icy Northern Prince Charles Mountains in East Antarctica.

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"When we cut them thin and made really thin sections and put under the microscope, we found that they are kimberlites," Professor Kamenetsky said.

Professor Kamenetsky says as mining in the area is banned, it is unlikely the discovery will be a money spinner.

"We'll never use these kimberlites as the source of diamonds, as a shiny gem product on our women. No, never," she said.

The scientists cut 30-micron-thin sections of the rock to identify it under a microscope. ( University of Tasmania: Vadim Kamenetsky )

Scientists say the kimberlites found in Antarctica are about 120 million years old.

Mr Yaxley says it could have been forced up from deep beneath the Earth's surface during a continental shift.

"We believe that during the separation of India from the Australian Antarctic continent there was a bit of movement along faults and so forth, and that can cause a little bit of melting deep in the Earth which may have resulted in these kimberlites," he said.

He sees the discovery as a small but important insight into how the Earth has evolved over billions of years.

"If you reconstruct those continents back into the original Gondwana configuration, so before they drifted apart, you have a vast province, a huge area, thousands of kilometres across, which contains these small but quite widely distributed 120 million year old kimberlites," he said.

"And now we've extended that province even further."