UNDER THE MICROSCOPE

Some plants have the ability to absorb metals from soil and store them. This is called an affinity, and plants have an affinity only to certain metals. At Mintek [the mineral research organisation where Tshiamo works] we identified a plant that is able to store gold: wheat. It releases enzymes that make gold soluble so it can absorb the gold and store it in its cells. The mature wheat can then be incinerated and the ash contains gold. This is called a bio-ore, which goes through a process of leeching to get the gold out (liquid extraction). Finally, the gold can be turned into a metal through smelting.