Rio Tinto recently reported an initial resource for the Winu deposit in Western Australia. At 1.8 million tonnes of contained copper, Winu is the most recent major discovery and also the largest in the past five years. Although it is encouraging to see the announcement of a significant new resource, this discovery unfortunately does little to alter the long-term trend of declining discovery rates. We continue to assess that current levels of exploration spending are insufficient to meet future demand, as demonstrated in declining discovery rates and a thinning project pipeline.
Winu was discovered during a 13,286-meter diamond drill and reverse circulation drill program conducted between December 2017 and the end of 2018 as part of a copper discovery program in the Paterson Province. The inferred resource, announced in late July, totals 503 Mt grading 0.35% copper, 0.27 grams per tonne gold and 2.15 g/t silver, making the deposit not only a major copper discovery but a major gold discovery as well. The deposit remains open at depth, to the north and to the southeast, meaning it will likely increase in size over the coming years. Rio is assessing development of the deposit as an open pit, with first production possible as early as 2023.
While a significant recent discovery, Winu is tied for the 126th-largest discovery since 1990. Our previously released copper discovery article has more information on trends and a list of all discoveries.
This article was published by S&P Global Market Intelligence and not by S&P Global Ratings, which is a separately managed division of S&P Global.