Argyle has been an open pit mine for more than 25 years, and is now transitioning to an underground mine to access the diamonds at depth.

Following extensive feasibility studies, the Rio Tinto Board approved the development of a unique block cave to be constructed beneath the open pit. This will be the first block cave mine in Western Australia, and one of only a few in Australia.

From 2013, operations in the open pit will begin to wind down as Argyle transitions to a fully operational underground mine. At full production the underground mine will generate around nine million tonnes of ore per annum and approximately 20 million carats of diamonds per year, over the life of the block cave.

The underground mine is expected to extend the life of the mine until at least 2020. The extended mine life will generate enduring benefits for the Kimberley region, building on Argyle's significant contribution to economic development over the past quarter of a century.

For more information on Argyle's underground mine, see the Argyle Diamonds Underground Mine Facts at a Glance.