The drilling, which follows up on extensive geochemical work, tested a 3,000-by-500-metre zone where soil piled in termite mounds carried gold at concentrations exceeding 0.1 gram per tonne. The partners drilled a series of 70 inclined reverse-circulation holes in eight fence patterns across the zone.
The holes indicated a zone of mineralization with a strike length of about 1.5 km, coinciding with the peak of the zone detected in the termite mound survey. The mineralization is developed in a quartz-chlorite-tourmaline schist unit sandwiched between beds of banded iron formation.
Gold grades ranged from 0.9 to 6.8 grams per tonne over hole lengths of 2.8 to 25 metres. Typical grades were in the 1-to-2-gram range. The hole angles — mainly 50 — imply a horizontal width of 1.8 to 16 metres for those intersections.
Rotary-air-blast drill holes drilled on similar targets to the south and southwest also intersected significant gold mineralization, with grades comparable to those on the main prospect.
Roandji, now held as a joint venture between Asquith and Axmin, came to Asquith in 1996 from now-delisted United Reef Resources. United Reef had been exploring diamond concessions in the CAR since about 1993, and dealt the property to Asquith for shares and a 3% net smelter return royalty, which has since been reduced to 2%.
The area, underlain by an Archean-aged greenstone belt, was known for placer gold production from the 1930s, but the source rocks of the placer deposits were never found. International aid agencies did some geochemical work in the post-independence period but were unsuccessful in finding the mineralization, probably because an iron-rich lateritic cap over saprolite soils masked the mineralization.
Termites, on the other hand, offered Asquith a well-disciplined and economical workforce capable of sampling at the boundary between the saprolite and the unweathered bedrock. Termite mounds 1 or 2 metres high are common throughout the concession, allowing sampling densities of around 150 per sq. km. A channel sample scraped from the side of the mound contains soil that the termites have brought to surface from deep in the saprolite. That was precisely what Asquith did, in an area that had been tagged as a possible gold target in earlier stream-sediment surveys.
Asquith’s approach included both geochemical analysis for gold and direct gold particle counts, and the two produced similar maps. The gold-enriched termite mounds formed a zone about 5.5 km long and 250-500 metres wide. Neatly, the zone coincided with an area of elevated arsenic concentration and the nose of a folded banded iron formation — a common geochemical associate of gold in a structural setting favourable for gold.
The gold particles, when examined under an electron microscope, were mainly fine-grained and delicate or wiry in shape, suggesting that they had not moved far from their hard-rock source.
Axmin, piloted by the same group that brought Samax Gold into East Africa and to a merger with
This spring, the partners plan to carry out a second phase of work, to consist of about 5,000 metres of reverse-circulation drilling on infill lines. Elsewhere on the 2,000-sq.-km property, crews will be doing regional mapping and more geochemical sampling.