25th Jul 2008 07:00
African Minerals Limited
("African Minerals" or the "Company")
Tonkolili Iron Ore Project Update
African Minerals Limited (AIM:AMI), the mineral exploration company with interests principally in Sierra Leone, West Africa, is pleased to provide the following update in respect of its flagship iron ore project at Tonkolili, Sierra Leone.
Highlights
Magnetite iron ore mineralisation in banded iron formation ("BIF") at Tonkolili confirmed over significant strike lengths and widths by systematic drilling
Total of 29,619 metres of drilling completed in 89 diamond drill holes at the Numbara and Simbili prospects, testing to approximately 400 metres vertically below surface with several holes terminating in mineralisation
High iron concentrate grades averaging approximately 68% Fe in magnetite concentrate iron ore product
Low levels of contaminants - silica (2,) alumina (2O3) and phosphorus (0.01% P)
Tonkolili Iron Ore Project Exploration Update
The exploration of the Tonkolili iron ore project has advanced rapidly with major diamond drilling programmes currently in progress on both the Numbara and Simbili prospects.
The first stage of the reconnaissance drilling programme was conducted on the Numbara prospect at Tonkolili between April 2007 and January 2008 with 2,767 metres of core drilling completed in 14 diamond drill holes. This work demonstrated the presence of significant magnetite iron ore mineralisation in BIF, leading the Company to undertake a major follow-up diamond core and reverse circulation drilling programme to define the size and grade of the mineralisation.
Several key infrastructure projects were commissioned by April 2008 to support the expanded drilling programme. These included construction of a modern camp, upgrade of the project access roads and construction of a sample preparation laboratory on-site under the management of AMDEL, a major Australian analytical services company.
(Note: The 'Figures' and 'Tables' referred to in this announcement can be accessed through the links provided in this announcement.)
Expanded Diamond Drilling Programme
The second phase of diamond drilling commenced in March 2008 with five diamond drill rigs now in operation and two reverse circulation drill rigs mobilised to site and awaiting commissioning.
At 20 July 2008, a total of 29,619 metres of diamond drilling has been completed in 89 drill holes at Tonkolili. Drilling has been initially focused on the Numbara prospect with 62 holes completed to date totalling 20,758 metres. This drill programme is testing an area of approximately 2,000 metres in length by 500 metres to 900 metres in width. Drilling is also in progress on the previously untested Simbili prospect with 27 drill holes completed, totalling 7,750 metres over an area of approximately 2,900 metres in length and 400 metres to 600 metres in width.
Drilling at both prospects has tested an average vertical interval of 400 metres below surface with localised deeper drilling to 500 metres. The drill hole collar locations for Numbara are shown in Figure 1 and for Simbili in Figure 4.
Significant Drill Hole Results
The second phase of drilling has further confirmed magnetite mineralisation in BIF at both Numbara and Simbili over significant widths and strike lengths.
Analytical results received to date for significant intersections from the diamond drilling at Numbara are listed in Table 1. Analytical results for Simbili are awaited from the laboratory.
The drill core samples were processed in the laboratory using Davis Tube Recovery ("DTR") equipment to recover a magnetic concentrate for analysis. These concentrates comprise about 30% by weight averaged over the significant drill hole intersections to date. The in situ iron grade in the BIF averages approximately 33% Fe. See Note 1 below.
The average magnetic concentrate from the significant BIF intersections at Numbara in Table 1 contain high iron (approximately 68% Fe), low silica (2), low alumina (2O3), and low phosphorus (0.01% P). See Note 2 below.
Numbara Geology
The BIF sequence at Numbara has a tested strike length of approximately 2,000 metres and dips steeply to the northwest at between 50 and 75 degrees. Geological cross sections for the northern and central part of Numbara are shown in Figure 2 and Figure 3. See Note 3 below.
Two discrete mineralised BIF horizons have been identified in the central part of Numbara. The north western horizon ranges from 80 metres to 400 metres in interpreted true thickness while the south eastern parallel horizon ranges from approximately 200 metres to 400 metres in interpreted true thickness. The geological contacts between the BIF and adjacent low-grade to unmineralised sediments are gradational with an envelope of lower grade BIF mineralisation surrounding higher grade BIF units. The mineralisation remains open at depth below 400 metres vertical depth. Further drilling is planned to test the potential northern and southern extensions of Numbara.
Simbili Geology
The BIF sequence occurs as a single unit dipping steeply to the northwest at 55 to 70 degrees. The tested dimensions of the mineralised BIF are 3,000 metres along strike with interpreted true widths ranging from approximately 100 metres to 500 metres. The mineralisation remains open at depth below 400 metres vertical depth. Drilling is planned to test the potential strike extensions to the north.
Analytical Results
While the Tonkolili drilling programme and sampling has progressed rapidly, drill hole analyses on magnetic concentrates were delayed due to insufficient laboratory capacity in Australia. This situation has been resolved by the acquisition and commissioning of additional DTR equipment to expedite analysis of the Company's samples.
Further geological information and analytical results will be published as results become available from the laboratory.
Figures
The figures for Tonkolili may be accessed on the African Minerals web site using the following links.
Figure 1:
http://www.rns-pdf.londonstockexchange.com/rns/8574Z_1-2008-7-24.pdf
Figure 2:
http://www.african-minerals.com/Doc/pdf/RNSDocuments/NumbaraGeologicalCrossSection_60950N.pdf
Figure 3:
http://www.african-minerals.com/Doc/pdf/RNSDocuments/Tonkoliliupdate-Figure3.pdf
Figure 4:
http://www.rns-pdf.londonstockexchange.com/rns/8574Z_2-2008-7-24.pdf
Table 1:
http://www.african-minerals.com/Doc/pdf/RNSDocuments/NumbaraDiamondDrillHoles_DTRAnalyses.pdf
Commenting on the update, Frank Timis, Executive Chairman of African Minerals said:
"Exploration activities at the Tonkolili iron ore project continue to make rapid progress. Results reported in this update confirm that our flagship project is moving into a new and exciting phase of its development, further demonstrating its potential to become a world-class iron deposit."
NOTES
1. DTR equipment magnetically separates the magnetic iron mineral, magnetite, from the BIF sample, providing a concentrate with significantly higher iron content than the in situ BIF. This concentrate is then analysed for iron and other elements. The weight recovery of the iron rich concentrate from the BIF is also measured.
2. The reported individual and average grades of the drill holes may not necessarily reflect the ultimate grade of the potential target.
3. The BIF percentage estimates on the geological cross sections are visual estimates only from core logging and may therefore be subject to significant estimation errors. Potentially economic grades may not be inferred from logged BIF occurrences without detailed analytical results. Reference must be made to Table 1 for the weighted average concentrate grades and weight percentage recovery of magnetic concentrate from the BIF.
4. Some statements in this news release are forward looking and consequently involve uncertainties and risks that could cause actual results to differ materially from those anticipated from initial indications. Such forward looking statements include comments regarding exploration work.
5. The information in this report relating to iron ore exploration results is based on information reviewed and compiled by Bruce Kirk, who is a Fellow of the Australasian Institute of Mining and Metallurgy. Mr. Kirk, President Iron Ore and Base Metals, is a full-time employee of the Company and meets the requirements of a "Qualified Person" under the AIM Guidance Note on Mining, Oil and Gas dated March 2006 for iron ore Exploration Results. Mr. Kirk has consented to the inclusion of this information in the form and context in which it appears in this report.
6. It should be noted that there has been insufficient exploration to define a Mineral Resource and it is uncertain if further exploration will result in the determination of a Mineral Resource. The grades of the drill holes presently reported may not necessarily reflect the ultimate grade of the potential target.
Enquiries:
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African Minerals Limited |
Tel: +44 (0) 20 7849 3002 |
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Frank Timis |
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Roy Pitchford |
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Canaccord Adams Limited |
Tel: +44 (0) 20 7050 6500 |
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Mike Jones |
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Mirabaud Securities Limited |
Tel: +44 (0) 20 7878 3360 |
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Rory Scott |
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Citigate Dewe Rogerson |
Tel: +44 (0) 20 7638 9571 |
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Martin Jackson |
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George Cazenove |
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