Significant Increase and Upgrade to the Mankarga 5 Resource
Perth, April 14, 2014 AEST (ABN Newswire) - West African Resources Limited (
ASX:WAF) (CVE:WAF) is pleased to report an updated independent resource estimate following recent drilling at the Mankarga 5 Deposit located on the Tanlouka Permit, part of its Boulsa Project, in Burkina Faso.
Managing Director Richard Hyde commented on the resource update: "We're very pleased that the resource upgrade has resulted in significant increases in contained ounces and grade in oxide, transitional and sulphide mineralisation.
"Core drilling and structural interpretation has enabled global ounces and grade in Indicated and Inferred categories in sulphide mineralisation to increase substantially. Indicated and Inferred Resources in this resource update have increased by 12% and 74% respectively.
"Importantly 77% of the oxide and transitional mineralisation is now classified as Indicated Resources, adding significant confidence to our near-term heap leach production strategy."
Highlights
- Indicated Resource increased by 12% (at a 0.5g/t cut-off) estimated at 10.8 million tonnes grading 1.3g/t gold containing 437,000 ounces gold
- Inferred Resource increased by 74% (at a 0.5g/t cut-off) estimated at approximately 32.7 million tonnes grading 1.0 g/t gold containing 1,050,000 ounces gold
- Indicated Resources (at a 1g/t cut off) estimated at 5.7 million tonnes grading 1.7g/t gold containing 315,000 ounces gold, and Inferred Resources (at 1g/t cut off) estimated at approximately 11.4 million tonnes at a grade of 1.6 g/t gold containing 568,000 ounces gold
- 29% of the Mankarga 5 Deposit classified as Indicated and 77% of the oxide and transitional mineralisation classified as Indicated
- Near-surface oxide and transition Indicated Resources (at a 0.5 g/t cut-off) estimated at 6.6 million tonnes at a grade of 1.2g/t gold containing 252,000 ounces gold; remaining nearsurface oxide and transitional Inferred Resources (at a 0.5 g/t cut-off) estimated at approximately 2.7 million tonnes grading 0.9 g/t gold containing 75,000 ounces gold
- Scoping Study for a low-cost heap leach project, targeting near term cash-flow from Mankarga 5 deposit and nearby prospects to be released later this quarter
- Auger and aircore programs underway testing nearby high-priority exploration targets
- West African aims to be a +50,000oz per annum gold producer within two years, subject to study outcomes
The resource update incorporates the results from the recent program of aircore drilling (4,601 metres) and ongoing deeper diamond drilling (1,283 metres) drilling, and is based on data from approximately 22,735 metres of combined reverse circulation and diamond drilling conducted during 2011 and 2012 by Channel Resources. The drilling extends over a strike length of approximately 3 kilometres, and to a maximum vertical depth of 250 metres with an average depth of 120 metres. The mineralisation remains open at depth and along strike. Excellent potential exists to increase the resource base with ongoing work at Mankarga 5 and from nearby mineralization at other targets.
Recent shallow drilling included in the Mankarga 5 updated resource has improved the oxide component in comparison to the previous estimate, and has added the transitional mineralisation component which was not previously modelled. The grade and tonnage improvement is primarily due to the increased density of drilling in the top 50m of the deposit and relogging of historic drilling, which has resulted in an overall increase in oxide grade by approximately 10% and an increase in contained global oxide ounces by approximately 30% (at a 0.5g/t gold cut-off). As a result 77% of the oxide and transitional mineralisation is classified in the Indicated category which provides increased confidence of these resource components leading into scoping studies for a heap leach starter project.
Targeted core drilling by WAF has also added further mineralisation at depth in the southern portion of the deposit. Important structural and lithological data has been recorded in new deep diamond drill holes which has been incorporated into the updated geological model. Table 1 shows the updated Mineral Resource and Table 2 in link below shows the historic Mineral Resource for the Mankarga 5 deposit tabulated at the same cut-offs.
Near-term Strategy
The Company aims to be a +50,000oz per annum gold producer within two years via a low-cost heap leach starter project at the Mankarga 5 deposit, subject to study outcomes and availability of financing. West African has secured a second-hand 1.6Mtpa heap leach plant as part of its plan to fast-track development of Mankarga 5. Detailed metallurgical test work is underway on Mankarga 5 drill core in Perth. Results of this test work, along with the updated resource estimate, will be incorporated into the scoping study which will be released by the end of this quarter. The proposed project development schedule for Mankarga 5 is shown in link below.
The Company will continue drilling throughout 2014 with aim of adding further resources suitable for heap leach treatment. Diamond drilling is also continuing at Mankarga 5 and aircore drilling has recently commenced at the Goudré prospect. An auger drilling program encompassing the entire Tanlouka permit has recently commenced which is designed to better define targets, ahead of drilling, at Mankarga 1 - 4, Manesse and Tanwaka. Figure 1 shows locations of prospects with exploration potential within a 25km zone in the south-western area of the Boulsa Project.
Figure 2 in link below shows all drill collars included in Mankarga 5 resource model showing grade distribution and a typical cross section through the deposit. Figure 3 is a long section through the deposit showing resource category.
Summary of Resource Estimate and Reporting Criteria
A summary of the material information used to estimate the mineral resource is presented below in accordance with JORC reporting guidelines. A more detailed description is contained in Appendix 1 (see link). Geology and Geological Interpretation
Rocks in the Mankarga 5 area comprise metasediments and volcanosedimentary units which have been intruded by diorite and granodiorite. The project area hosts shear zone type quartz-vein gold mineralisation. Gold mineralization at Mankarga 5 is associated with quartz veining with silica, sulphide and carbonate-albite, tourmaline-biotite alteration. The mineralised shear hosting mineralisation can be traced on 100m and 50m spaced sections over almost 3km. The mineralisation interpretation utilised a 0.2 g/t Au edge cut-off for overall shear zone mineralisation. Within this discrete higher grade Hangingwall and Foot-wall zones were modelled using a 0.5 g/t Au edge cut-off.
Sampling and sub-sampling techniques
WAF and CHU RC samples were split and sampled at 1m and 2m intervals respectively using a three-tier riffle splitter. Diamond core is a combination of HQ, NQ2 and NQ3 sizes and all Diamond core was logged for lithological, alteration, geotechnical, density and other attributes. In addition, WAF Diamond core was logged for structural attributes. QAQC procedures were completed as per industry standard practices.
Drilling Techniques
The area of the Mankarga 5 resource was drilled using Reverse Circulation (RC), Aircore (AC) and Diamond drill holes (DD) on a nominal 100m x 25m grid spacing with infill on 50m spaced lines in several areas. A total of 116 AC holes (4601m) and 8 DD holes (1283.2m) were drilled by West African Resources (WAF) in 2013-2014. A total of 60 RC holes (7296.2m) and 71 DD holes (15439.6m) were drilled by Channel Resources (CHU) in 2010-2012. Holes were angled towards 120° or 300° magnetic at declinations of between -50° and -60°, to optimally intersect the mineralised zones.
Classification
Resource classification was based on geological confidence and spatial review of quality coding which reflected the quality of the estimate for each block. Areas within the Hanging Wall and Footwall zones that had high confidence estimate values, had sufficient drilling density (<50m spaced drilling) or were proximal to 100m by 25m spaced drill lines were assigned as Indicated Resources. The remainder was classified as Inferred.
Sample analysis method
Historic and recent RC and diamond core samples were crushed, dried and pulverised (total prep) to produce a sub sample for analysis for gold by 50g standard fire assay method (FA) followed by an atomic absorption spectrometry (AAS) finish.
Estimation Methodology
Ordinary kriging was selected as the most appropriate method for estimating Au for the Mankarga 5 deposit. A block size of 5m X, 25m Y and 10m Z was selected as an appropriate block size for estimation given the drill spacing (50 to 100m strike spacing), mineralisation geometry and the likely potential future selective mining unit (i.e. appropriate for potential open pit mining). A zone and zone percentage coding was used to accurately represent domain volumes.
Cut-off grades
The resource is reported at cut-offs of 0.5 g/t Au and 1.0 g/t Au which were considered reasonable and reflect that the final cut-off determination will be dependent on the scale of any potential future operation. High yield limits were used to restrict the influence of high outlier grades. A high yield limit of 10 g/t Au was used based on the 99th percentile values. The high yield limit was restricted to within 25m of an outlier grade. The removal of outlier grades removes approximately 8% of reported Au metal.
Mining and metallurgical methods and parameters and other material modifying factors
The most likely development scenario for the deposit is as an open cut (pit) mine. No mining dilution has been applied to the reported estimate. Preliminary metallurgical test work was completed for Channel Resources in 2012 by SGS Laboratories in Vancouver. Cyanide bottle roll tests returned recoveries of 93% to 95% for oxide and 85% to 92% for sulphide mineralisation. Coarse bottle roll test work to test the amenability of material to processing by heap leach methods returned recoveries of 79% for oxide and 30% for sulphide. More detailed metallurgical heap leach test work is currently underway at ALS Ammtec in Perth. Results are expected by the end of this quarter.
To view tables, figures and charts, please visit:
http://media.abnnewswire.net/media/en/docs/ASX-WAF-673956.pdf
About West African Resources Limited
West African Resources Limited (
ASX:WAF) (CVE:WAF) is a gold-copper exploration company dedicated to creating shareholder value through the acquisition, exploration and development of resource projects in Burkina Faso, West Africa.
West African has a landholding of 6,370sq km and 200km of strike length of early Proterozoic Birimian greenstone belts, which are highly prospective for gold mineralisation.
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