Nautilus Minerals Inc., which is focused on exploring for mineral deposits on the ocean floor, said on Friday positive drill results have allowed it to raise its resource estimate at its Solwara 1 copper-gold project that is located off the coast of Papua New Guinea. The increases in contained metal within the resource are a result of additional tonnes, and importantly, higher grades, due to successful resource drilling which identified further high grade ore zones. The increase in tonnes was also partly due to a reduction in the cut-off grade from 4% copper, used in the prior 2008 resource statement, to a copper equivalent cut-off grade of 2.6% in the 2011 resource, following refinements in the project design. Nautilus president and CEO Steve Rogers said the notable increase in the company's resource base demonstrated the success of the exploration campaign, extending the life of the Solwara 1 Project and delivering an improved knowledge of the Bismarck Sea geology.
The company further raised the size of its contained copper and gold resources, as its drill campaign located higher grades. The Vancouver, British Columbia-based company said total indicated resources at the site have risen 18 per cent, and a 36 per cent increase in inferred resources over the company's previous 2008 estimate. It also raised the size of its resources in the inferred category to 1.8 million tonnes. The company was able to significantly boost its NI 43-101 compliant resource base by lowering its copper cut-off grade to 2.6 per cent, from four per cent, it said. The results of the update are based on 276 drill holes, mainly the company's 1,475-metre drill campaign conducted between November 2010 and May 2011. At the 2.6 per cent copper grade, the Solwara 1 property has 1.03 million tonnes grading 7.2 per cent copper and 5.0 grams per tonne (g/t) gold, for 74,160 contained tonnes of copper and 165,500 contained ounces of gold in the indicated category. In the inferred category, Nautilus has 1.54 million tonnes at 8.1 per cent copper and 6.4 g/t gold, for 124,740 tonnes of copper, and 316,900 ounces of gold. At the previous 4 per cent copper cut-off grade, the Solwara 1 project has 70,070 tonnes of contained copper and 158,000 ounces of contained gold in the indicated category, and 120,120 tonnes of copper and 302,800 ounces of contained gold in the inferred category. On the Solwara 12 deposit, at the 2.6 per cent copper cut-off grade, the company measured 230,000 tonnes grading 7.3 per cent copper and 3.6 g/t gold for 16,790 tonnes of contained copper and 26,600 ounces of contained gold in the inferred category. The Solwara 1 resource estimate also contained substantial zinc and silver.