Rio Tinto has strengthened its global uranium resources with the upgrade of its mineral resources and ore reserves at its 69 per cent-owned Rössing Uranium Limited in Namibia.

The 2010 annual assessment shows a more than doubling of contained metal in Mineral Resources, increasing 164 per cent, complemented by an eight per cent increase in recoverable metal in Ore Reserves since the 2009 statement. The additional 2010 Resources are immediately under and adjacent to the existing mining operation. Rio Tinto Energy chief executive Doug Ritchie said: "This is a significant upgrade to what has long been recognised as a world-class ore body. It will add significant value to Rössing Uranium Limited and Rio Tinto, particularly during this period of strong long-term
demand growth."

Rössing's Managing Director, Mike Leech, said: "This is a very exciting time for Rössing and our employees, customers and stakeholders as the additional resources may lead to a longer mine life and increase the production options open to us. We have an active and ongoing exploration program on the Rössing lease and look forward to further positive
results. We are progressing mine planning studies to improve confidence in our resources and allow conversion to reserves and formal further extension of mine life. The increase in grade of Ore Reserves will result in lower unit costs, providing a boost to Rössing's competitiveness amongst other uranium producers."

Rössing Uranium Limited

Registered in Australia Rio Tinto Limited 120 Collins Street Melbourne 3000 Australia ABN 96 004 458 404

Rössing Uranium Limited is a leader in the mining and processing of uranium in Namibia, in south-western Africa and is the owner and operator of the Rössing mine, a large openpit uranium mine about 70 kilometres inland from the coastal town of Swakopmund in the Erongo Region. Rössing Uranium Limited is owned 68.6 per cent by Rio Tinto. Operations at Rössing commenced in 1976 and have produced more than 260 million pounds of uranium during that time. Rössing has been a major and enduring contributor to the Namibian economy and local communities. Rössing is one of the largest private employers in Namibia with more than 1,500 full time employees and some 1,700 contractor roles. More than 98 per cent of the workforce is Namibian. The mine site itself encompasses a licence area of about 180 kilometres2, of which 20 kilometres2 are used for mining, waste disposal and processing.

Rössing is the third largest uranium mine in the world, with the open pit approximately 3 kilometres by 1.2 kilometres and 390 metres deep.

Rössing SJ pit looking east

Rössing geology

Rössing is a world-class granite-hosted uranium deposit located in the Damara Orogen of Central-West Namibia.

Economically important uranium mineralisation is hosted by early Palaeozoic-age late- to post-tectonic granitic intrusive dykes referred to locally as "alaskites".

Alaskites mainly occur in highly metamorphosed rocks in the central part of the Damara Orogen, where they are preferentially developed in anticline and dome structures and in several discrete metasedimentary rock units including the Nosib Group and lower Swakop Group.

Individual alaskite bodies are highly irregular and vary in width from micro-scale to greater than 200m and in length from centimetre scale to several kilometres. The Rössing deposit contains a large steeply dipping uraniferous alaskite body, which extensively intrudes a highly folded sequence of metamorphic rocks at the contact of banded gneiss and marble units.

Uranium mineralisation at Rössing occurs in veins and as disseminated grains within and adjacent to alaskite bodies.

Reserve and resource update

Rössing undertook a programme of drilling and resource modelling during the past year that resulted in an updated block model, which is characterised by a significant increase in both U₃O₈ grade and overall resource tonnage.

The 2010 annual assessment includes fully updated geological and structural control models, results from infill pit floor drilling and updated price, productivity and operating assumptions. These new studies result in a 164 per cent increase in contained U₃O₈ in Mineral Resources and an eight per cent increase in recoverable U₃O₈ in Ore Reserves compared to the 2009 statement.

The newly identified resources are subject to active technical and mine planning studies focussed on converting the additional material into Ore Reserves.

Rössing Uranium Limited

The Mineral Resource and Ore Reserve statements below are determined in compliance with the JORC Code.

Notes:

• Data for Reserves shows the recoverable U₃O₈ in Mlbs, which reflects an overall mill recovery factor of 84 per cent.
  
• Data for Resources represents the 100 per cent contained U₃O₈ in Mlbs.
  
• Reserves (tonnes and grade) are declared based on a variable scanner cut-off grade as per current Rössing operating practices.
  
• Resources are stated at a cut-off grade of 100ppm.
  
• Resources are shown exclusive of Reserves.
  
• Rössing Reserves and Resources are quoted on 100 per cent ownership basis.
  
• Reserves and Resources are based on ore tonnage and grades across multiple zones and estimates may be subject to rounding errors. The figures above are sometimes more precise than the rounded numbers shown, hence an apparent small difference may result where numbers are totalled.

The information in this document that relates to the Rössing Mineral Resources and Ore Reserves is based on information compiled by mining engineer Wulff-Dieter Wieland (a full time contractor to Rössing Uranium Limited) and geo-statistician John Forkes (a full time employee of Rio Tinto plc). Wulff-Dieter Wieland is a member of the Southern African Institute of Mining & Metallurgy. John Forkes is a member of the Institute of Materials, Minerals and Mining. Wulff-Dieter Wieland and John Forkes have sufficient experience which is relevant to the style of mineralisation and the type of deposit under consideration, and to the activity which they are undertaking, to each qualify as a Competent Person as defined in the 2004 edition of the "Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves." Wulff-Dieter Wieland and John Forkes consent to the inclusion in this document of the matters based on their information in the form and context in which it appears.

About Rio Tinto

Rio Tinto is a leading international mining group headquartered in the UK, combining Rio Tinto plc, a London and NYSE listed company, and Rio Tinto Limited, which is listed on the Australian Securities Exchange.

Rio Tinto's business is finding, mining, and processing mineral resources. Major products are aluminium, copper, diamonds, energy (coal and uranium), gold, industrial minerals (borax, titanium dioxide, salt, talc) and iron ore. Activities span the world but are strongly represented in Australia and North America with significant businesses in South America, Asia, Europe and southern Africa.

For further information, please contact:

Website: www.riotinto.com
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