I was all set to watch the ABC's Catalyst on Thursday when I was interrupted by a loony phone call involving a can opener, a neighbour and an Avon book. Don't ask, I couldn't do the saga justice by trying to blog it. Anyway I missed most of the segment on termites and how geologists are using them to look for minerals. I had read an article about this in New Scientist last year.
A geologist in the 1970s found a speck of ilmenite on the surface in the Kalahari desert. Ilmenite comes from kimberlite and kimberlite has diamonds and the geologist had just discovered the richest diamond deposit in the world, the Jwaneng diamond mine. That speck came from 40 metres down and was hauled to the surface by termites.
Australian researchers are developing techniques to sample termite mounds for traces of gold, diamonds and other minerals. The termites constantly have to repair the mounds to control the temperature and keep out predators so they tunnel down to the water table and bring back clay or wet rock and it's this deep soil that holds whatever traces of minerals. So instead of expensive drilling machines, geologists are using the services of termites for free.
The inside of the mounds is a type of regurgitated mud cement containing organic material, fine rock particles and geologists scan samples for elements such as chromium, titanium, arsenic, all of which can occur in rocks containing gold. The termite tunnels can go down 30 metres or more but researchers are also looking at Spinifex grass.
Chewed up spinifex has been found in the termite mounds and showed signs of mineralization. The spinifex put all their growing effort into sending down roots to groundwater, sometimes 50 metres or more. Sampling the grass shows the chemicals it has taken up with the water and accumulated in the leaves. Spinifex and termites concentrate different minerals but together this provides a geochemical picture of what could be underground. It sounds way out but in the Tanami desert less than 1 per cent of the landscape has rocks exposed above ground and these have revealed some of the largest gold deposits in Australia and since these rocks extend underneath it means that 99 per cent hasn't been sampled. Cue the termites.
The image above is north of the Granites gold mine in the Tanami Desert. It was taken during a combined dust storm and thunderstorm close to sunset. The Sun is wedged between dust and rain cloud.