For the record. here is the full text of the article. Notice the words "low grade" are not there.
Now, the days when massive mineral deposits could be simply spotted by plane are gone, so miners are adopting new lab techniques and machine-led mapping to detect metal traces in everything from sand to gum tree leaves and groundwater.
Australian miners are taking a deeper look at the 80 percent of the country that lies “under cover” - obscured by meters of sediment and sand, particularly in the desert interior, across an area twice the size of India.
They are using a mix of new techniques and established methods in new ways, backed by greater computing heft, including a new generation of multi-layered maps produced by Australian government agencies.
“There has been a perception that Australia is a mature destination and all the big finds have been found,” said Will Robinson, managing director at Encounter Resources, which is exploring for gold using a new type of soil sampling developed by the CSIRO, Australia’s peak science body.
“You’re seeing more success as companies go out there and supply new technologies and new thinking into areas to find new big deposits,” he said. “It has reset the maturity clock.”
Having repaired their balance sheets on the back of a commodities price recovery, miners large and small are rushing to peg out prospective land in undercover areas.
Anglo American told Reuters it has recently been granted or is seeking permits over almost 11,000 square km of land in Queensland state, while iron ore miner Fortescue Metals Group raised its exploration tenements by a third last year.
Rio Tinto also sharply increased its exploration holdings under the remote Great Sandy Desert, where it announced a large copper find last week.
Encounter Resources last month reported a gold find under shallow sand using CSIRO’s Ultrafine Soil technique, sending the explorer’s shares up 30 percent.
“These ancient landscapes have buried deposits,” said Ryan Noble, a CSIRO scientist leading the development of the process.
The analysis relies on separating out large particles of sand, which in remote Australia can account for as much as 95 percent of a sample, from much smaller clays and iron oxides, which attract gold, copper and zinc.
Developments in analysis mean smaller particles of 2 microns can now be detected, about one-50th the size of a grain of salt, revealing signs of mineralization as deep as 10-20 meters (30-65 feet) under soil or sand.
“We think there is huge value for Australia and other places to reprocess the samples they have collected and generate new targets and open up new areas,” CSIRO’s Noble said.
Other new techniques are also starting to show results.
In South Australia, ASX-listed Marmota is using a biogeochemical leaf analysis which helped guide it to a high-grade gold strike at its Gawler Craton project in September.
Gum trees siphon up minute traces of gold from their roots to their leaves, which are then analyzed in a lab.
“The gums were able to pick up moderate mineralization down to about 60 meters (200 feet),” geologist Aaron Brown told Reuters.
The technology was developed during the boom years of 2012-2013 but has taken time to be used commercially as miners and investors look to reinvest in exploration after several lean years.