Termites lead explorers in Mali to gold

Nicknamed “geozoology,” or “termite geochemistry,” mineral exploration companies in Mali are still turning to termites as an important tool in the search for gold deposits. By sampling termite mounds, which often tower more than two metres high in the country, geologists have access to a wide sample of the underlying minerals covering a prospective area.

In search of water, termite colonies can burrow as deep as 80 metres underground, depending on the hardness of the rock and the depth of weathering, and transport material along the way to the top layer of the mound. If they dig through important mineralization on their way down, this will typically be represented in a series of mound samples.

The downside of termite mound sampling, however, is determining from what depth or lateral area the grain of mineralization might have come from before being displaced by the termite.

As Ambogo Guindo, a Malian geologist and vice-president of Legend Gold (LGN-V), explains, “We think it is representative of what is beneath. Where you get the anomaly on the surface is not (always) where it is, however. Termite mounds will give you almost the right place. You are in the same area, anyway.”

Exploration companies use these samples in conjunction with surveying, mapping and regular soil sampling to help determine prospective drill targets. Legend Gold (formerly North Atlantic Resources) has used the technique at its main Tiekoumala gold project since 2003, helping guide drilling efforts which have delineated a 594,000-oz. indicated and inferred gold resource. Guindo says his team will take another 5,000 termite mound samples at the project this month.

Some proponents of the technique even claim the world’s richest diamond mine, De Beers‘ Jwaneng in Botswana, was found with the help of termites. As the story goes, in 1972 a De Beers geologist found a fleck of the kimberlite indicator mineral ilmenite near a termite mound. The ilmenite discovery led to further exploration, which revealed ilmenite mineralization 40 metres below and eventually led to the discovery of Jwaneng’s diamond-rich kimberlite pipes.

Researching similar rumours about the Sadiola gold mine in Mali, 41% owned by Iamgold (IMG-T, IAG-N), proved less promising. Pierre Lalande, now a director of African Gold Group (AGG-V), was a senior consulting geologist for Watts, Griffis and McOuat around the time of Sadiola’s discovery who helped prepare a preliminary economic assessment for the project.

He says soil sampling, not termite mound sampling, “led to the rediscovery of gold diggings,” which ultimately led to the discovery of the deposit between 1987 and 1989. The Malian government carried out the initial rounds of exploration at Sadiola in a program financed by the European Development Fund. It found high gold, arsenic and antimony anomalies at the site and widespread evidence of artisanal gold workings up to 900 years old. Samples from termite mounds were only taken “long after the start of the first resource estimate,” recalls Lalande. 

With African Gold Group, Lalande now oversees the company’s exploration programs on its main Malian gold project, Kobada. In early 2011, it discovered a new gold zone at Kobada which has been aptly named the Termite zone, after sampling at several large termite mounds returned anomalous values of gold and resulted in the successful establishment of drill targets. African Gold says the Termite zone is a separate and distinct structure about 1.5 km from Kobada’s main zone. Recent drill results from Termite include 12 metres of 2.7 grams gold per tonne and 3 metres grading 9.16 grams gold.

Then there is Merrex Gold (MXI-V), which bills itself as the largest holder of contiguous gold exploration permits in Mali. The Nova Scotia-based company signed a joint venture agreement with Iamgold in late 2008 for its main Siribaya gold project, in which Iamgold is earning a 50% interest over four years by spending $10.5 million on exploration. It has spent roughly $6.8 million so far, completing diamond and reverse-circulation drilling, airborne surveys, soil sampling and termite-mound sampling.

In early March, the JV partners began a 10,000-metre diamond drill program at Siribaya with a goal to increase the present National Instrument 43-101 resource up to 1 million gold oz. The current resource stands at 378,000 gold oz., composed of 4.01 million indicated tonnes grading 2.39 grams gold plus 946,000 inferred tonnes at 2.29 grams.

Another Iamgold joint venture partner in the area, Channel Islands-based Avnel Gold Mining (AVK-V), recently finished taking 21,000 samples of termite mounds over a 60-sq.-km priority zone on its main Kalana gold project. The partners added a third drill rig to the site in March.

Other gold exploration companies in Mali sampling termite mounds include Frontline Gold (FGC-V), Compass Gold (CVB-V) and Northquest (NQ-V).