To find gold, miners may look for various elements associated with gold known as pathfinder elements (silver, copper, zinc, nickel, mercury, arsenic and barium). It’s much easier to find the pathfinder elements than it is to find gold, and geochemical mapping the distribution of these elements help focus the search area to determine if gold is nearby.
Now Australian researchers have published a study in the journal Geology suggesting that trees, and termites, may be new gold “pathfinders”. According to Mining.com, the team analyzed hundreds of samples of sediments, soil and acacia leaves from a gold mine near Kalgoorlie, Western Australia. Based on the gold content in the samples, the researchers concluded that the aspect and condition of tree leaves and soil, as well as the presence of termites, should be considered key indicators of the presence of gold deposits in a certain area. Canadian mining exploration firm Angkor Gold supports the Australian team’s findings. The company has identified concentrations of gold and base metals such as copper and molybdenum in samples collected from more than 110,000 termite mounds in Cambodia.
This could be good news considering how costly and difficult traditional gold mining is. Given the market volatility of the past five years, companies mining for precious metals face continuing pressure to cut costs and quickly identify the most economically viable resources. Some of the issues they face are:
- Typical prospecting involves examining samples from just a few areas throughout the mine site to determine if the region is worth exploring. Because gold occurs in such small concentrations, it’s easy to miss using this technique.
- It’s becoming harder to find Greenfield sites with potential, so mining companies are spending more to get less.
- When deposits are located, few of them have large enough concentrations to be financially worthwhile to pursue; many discoveries will be abandoned without further development.
To enhance their chances of finding gold, geologists may use geophysical methods to measure variations in the physical properties of rocks (e.g. density, magnetism, electrical conductivity, natural radioactivity, etc) that may indicate the presence of suitable environment for gold deposition. Although these geophysical methods can be crucial for gold exploration, geochemical methods – including portable x-ray florescence (XRF) – are the only methods that can measure concentration of gold and other associated elements. Today, portable XRF is used in various stages of gold exploration and mining including grass-root exploration (particularly using pathfinder elements), finding source of gold in stream sediments, core logging, identification of lithologies, and even grade control.