Resource World Magazine

O C T O B E R / N O V E M B E R 2 0 1 8 www.resourceworld.com 31 GOLD tected by the actions of billions of micro-organisms. Bacteria evolved in the very early Precambrian era. The Cambrian period started 600 million years ago and bacteria first evolved about 3.5 billion years ago. Cyanobacteria evolved about 2.8 billion years ago. When it comes to gold, the most influential form of life has to be cyanobacteria. This is a form of blue green algae which evolved the ability to make carbohydrates out of seawater in the presence of sunlight and was one of the first forms of life to accomplish the feat of photosynthesis. A lesser known ability of bacteria is its ability to dissolve, transport, concentrate and precipitate gold. For the last decade, researchers at the University of Adelaide in Australia have been investigating the role that bacteria play in the movement of gold from deep within the earth's crust to its precipitation as tiny grains in rocks, and then subsequent move - ment and re-precipitation of gold in the surface environment. It was previously thought that gold was an inert element which does not combine with other elements to form minerals, and that it was impervious to biological actions. "Primary gold is produced under high pressures and tempera - tures deep below the Earth's surface and is mined, nowadays, from very large primary deposits, such as at the Superpit in Kalgoorlie," says Dr. Frank Reith, Australian Research Council Future Fellow in the University of Adelaide's School of Biological Sciences, and Visiting Fellow at CSIRO Land and Water at Waite. See accompa- nying photo of the Superpit Gold Mine in Kalgoorlie Australia. "In the natural environment, primary gold makes its way into soils, sediments and waterways through biogeochemical weather- ing and eventually ends up in the ocean. On the way, bacteria can dissolve and re-concentrate gold – this process removes most of the silver and forms gold nuggets." Scientists discovered that bacterial films form on the surface of gold grains and have identified specific species of bacteria which can dissolve and precipitate gold. This has opened up a brand- new avenue of research on applying bacteria to extract gold from gold ores, tailings and industrial wastes. Researchers have also developed a new technique to estimate how much gold was in oceans billions of years ago. The team led by the University of Tasmania's ARC Centre of Excellence in Ore Deposits (CODES) created a "time series curve" that shows how gold concentrations in the oceans have varied through time over 3.5 billion years. The research found that gold was far more abundant in the oceans at certain periods in the past, whereas at other times, gold was virtually absent from the oceans. The time series curve indi - cates that three billion years ago there was 10 times the gold in the ancient oceans compared to the modern oceans – more than info@mcewenmining.com | 1.866.441.0690 | mcewenmining.com MCEWEN MINING Outperforming our peers and the broader market Black Fox Timmins, Canada Paid $0.06 on the $ Intercepts up to 20 oz/t Building resources Gold Bar, Nevada Production in 2019 Building resources El Gallo, Mexico Extending LOM by 12 Years Los Azules, Argentina Biggest possible value creator San José, Argentina Continuing - High-Grade Production Rob McEwen Ownership 24% CHECK OUT WHAT YOU HAVE MISSED FROM OUR MCEWEN MINING INVESTOR DAY www.youtube.com/c/McEwenMining LEFT: The Superpit Gold Mine (Fimiston) in Kalgoorlie Western Australia of Kalgoorlie Consolidated Gold Mine, owned 50:50 by Barrick Gold and Newmont Mining, which open in 1893. Photo by Alf Stewart.

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