MINERALS OPPORTUNITIES

Gold
The rivers of Rio Muni are worked by local artisans using simple panning and wooden sluice technologies. Previous commercial investigations have concentrated on the three main areas of artisanal workings - Coro, Aconibe, and Mongomo and there are several other known occurrences that have been worked. Historical records are incomplete, but at least 2300 kg (74,000 0z) of gold was produced from the Coro area alone in the mid-70's.

The alluvial gold is relatively coarse grained, occurring as either dendritic or rounded nuggets, mostly in the 350-180um size range, although larger nuggets up to 4mm x 8 mm are relatively common. The common occurrence of the gold with vein-quartz, clays, and lateritic minerals attests to the proximity and variable types of bedrock gold mineralisation which have yet to be delineated.

Diamonds
Heavy-mineral sampling results have identified zinc-rich chromites in the Nsork area, similar to those found in the diamondiferous lamproite dyke swarm at Mitzic (Gabon), 50km to the southeast. Remote sensing and limited outcrop mapping show the dyke swarm trending into the southeastern corner of Rio Muni. Furthermore, exploration in Gabon for both gold and diamonds has identified trails of indicator minerals and diamond right up to the southern borders of Rio Muni. Detailed exploration work is required in the Nsork area to establish the primary sources of the diamonds.

Columbo-tantalite
Mineralisation has been defined in the Aconibe and Ayamiken areas by Nb and Ta soil anomalies and by the presence of heavy minerals commonly associated with Nb-Ta-bearing pegmatites. Neither area has been explored in great detail and thus they represent early stage exploration prospects for pegmatites and skarn systems associated with PanAfrican granitic intrusions. The Aconibe occurrence comprises discrete, laterally extensive pegmatites that are also overlain by eluvial and alluvial deposits yielding grades of 3.0 to 7.5kg/m³. Sample assays have demonstrated niobium-rich columbo-tantalite (62.36% Nb₂0₅) with subordinate tantalum (18.74% Ta₂0₅).

Other mineral potential
Widespread lateritisation and indications of bauxitic laterite, with grades up to 58.3% Al₂0₃, and 2.1 % to 5.3% SiO₂, indicate some potential for bauxite. Anomalous values of base metals, U, As, Ag, Mn and Mo have been detected in laterite above black shales in the Noya Series which is part of the West Congolian foreland basin. This has known base metal deposits immediately to the south in Gabon, and is also equivalent in age to the Katangan sequences of the Democratic Republic of Congo and Zambia. Basic intrusives have been mapped in southern Rio Muni, that may be a northern extension of the Kinguélé ultrabasics trend of northern Gabon, which contains known Ni-PGE mineralisation. Serpentinised ultramafics in central Rio Muni are as yet untested exploration prospects with some potential for base metals and platinoid elements.