Mercury-free Gold in the 2016 Rio Olympic Medals: Begs the Question – Why is Mercury Used to Mine Gold in the First Place?

Rio Olympics silver gold and bronze medals

Brazil is the home to the Amazon Rain Forest, so diverse in fauna and flora that Brazil is considered a “megadiverse country”, one that demands greater global attention in preserving its biological riches. With the ultimate global party – the 2016 Olympic Games – about to commence in Rio de Janeiro, authorities are ensuring that messages about environmental protection are given priority.

On June 14, Rio 2016 and Brazilian Mint held a press conference to display the medals to be awarded to top three finalists in the Olympic and Paralympic competitions to be held in August and September this year.

The talking points:

  • The nearly 2,500 gold, silver and bronze medals were produced according to strict sustainability criteria.
  • The gold medals were formed by gold that was extracted without the use of mercury.
  • Thirty percent of the silver and bronze medals are made up of recycled materials.
  • Half of the plastic in the ribbons that will suspend the medals were made from recycled plastic bottles.

What caught my eye? The fact that mercury wasn’t used in the mining of gold. I know mercury is a substance humans generally want to avoid direct exposure to. One of Japan’s most infamous environmental health cases and lawsuits are based on a Japanese company in Kumamoto that routinely released mercury into Minamata Bay, causing thousands of cases of mercury poisoning. In Japan, that condition is called Minamata Disease.

What I didn’t know was that mercury has become a popular tool for mining gold. Chemically, mercury and gold attract, or as the scientists would say, mercury amalgamates to gold. This small understanding of chemistry has motivated miners to use mercury in a variety of ways to separate gold specs from rock and dust.

The video below on artisanal gold mining demonstrates the process. First miners pick away at walls of rock with the understanding that gold nuggets an gold dust are in the seams. Large chunks of rock are then handcrushed, and then crushed further by mechanized processes. When the rock has been reduced to pebbles and dust, water is added. At this stage, mercury, which is a liquid element easily purchased, is added to the mix.

Mercury and gold attract, form an amalgam, and thus are easily gathered from the gold-mercury-water slush.

While coming into contact with mercury is not a good idea, as the workers inevitably do in this process, the next step is the most life threatening. The amalgams are then heated so that the gold can be separate from the amalgam. Essentially, the mercury is burned off, released in fumes. It is those fumes that are inhaled by the workers.

The end of the video leads to a conclusion that makes me wonder why gold is so important in the first place: one ounce of gold is mined from one ton of ore using mercury amalgamation techniques. It is good that the 2016 Rio Olympic gold medals are not mined from that poisonous process. But like blood diamonds, poison gold needs to be outlawed.