Total area of 121 Square Kilometres of potential alluvial deposit.
Surveyed with GPS all artisanal alluvial workings collecting information on average gold grade and grain size occurrence.
Grades ranges between 0.2 – 5g/t Gold.
Considering 60% of swamps already mined = +500,000 oz resource @1g/t in 40% “virgin” swamps. In 60% “mined” swamps given 70% artisanal recoveries and 30% waste = ~150,000 oz @ 0.5 g/t =TOTAL 750,000 oz @ 0.8 g/t.
ALLUVIAL COLTAN SUMMERY
Over the past 3-4 years there has been a significant amount of artisanal alluvial mining for coltan mainly centred around the Matanta/ Wilkinson Hill area on.
There is a reported “illegal” production of between 20 to 30 tonnes of coltan /month from the Licences.
Quality and grade of the coltan is reputed to be “the best in Sierra Leone” with high tantalum/ niobium grades, which together with having a very low radiometric signature and a well documented “chain of custody” makes it ideal for international markets.
The company have carried out exploration programmes for alluvial, eluvial coltan as well as working with local artisanal alluvial/eluvial miners through which they have purchased and sold 15 tonnes of coltan.
As noted, The excavated 204 pits in 19 swamps and collected a significant amount of data from working closely with the artisanal workers – based on this information it is estimated that there is the potential for +6000 tonnes of Aluvial coltan and associated minerals in the 19 swamps in the Matanta area.
Tantalum and niobium grades are variable but assay results from reputed laboratories suggest an average product grade should be >20% Ta2O5 with minimum pre processing to remove accessory minerals from the finer grained fractions.
Given a tantalum price of US$35/kg (+20% Ta2O5) the in-situ value of the estimated coltan in the swamps in the Matanta area is US$20 million.
NOTE –concentrate assays returned tin values averaging ~1% Sn from 8 Matanta swamp samples (present tin price is US$ +22,000/tonne) .
204 test pits in 19 swamps in the Matanta prospect to test the potential for economic alluvial coltan concentrations.
The coltan occurs in “pseudo” gravels with grade and grain sizes / ratios varying within swamps and across the prospect area.
Coarse coltan reports higher Ta2O5 and Nb2O5 grades than the finer concentrates due to the dilution effects of gangue minerals in the fine sub 1mm fraction.
The sub 1mm size concentrate may contain between 10-40% gangue minerals which include tin, ilmenite, zircon, gold, magnetite, etc
To viably recover 90% of coltan and accessory minerals from swamps a density or gravity concentrator unit (DMS/ spiral or Knelson concentrator) should be used.
Based on work centred on swamps, mined and unmined by the artisanal miners (see map on left) including 204 pits in 19 swamps in the Wilkinson Hill area, there is the potential for an estimated +1,000 tonnes of coltan (tin – gold).
Proposed programme to trench at 100m intervals across one non-mined swamp and one “mined swamp” using adapted back-hoe and mobile processing plant.