African Aura Mining Inc. (TSX-V:AUR; AIM:AAAM), exploration and development company with divisions focused on iron ore and gold in sub-Saharan Africa, announced the simultaneous filings of Mineral Resource Estimates pursuant to National Instrument 43-101, relating to the Company's 100% owned Nkout iron ore project located in southern Cameroon and its 38.5% Putu project in eastern Liberia.

Further information about Nkout, Cameroon Skip toPutu

Overview

 

• Ownership: 100%
• Resource: 1.04Bt at 34% Fe (from 3km section)
• Management Target: 4Bt
• Licence size: 998 km²
• Test work proves high grade concentrate and sinter fines potential
• Target: Major geophysical anomaly 20km in length
• Status: Grab sampling with highly encouraging grades up to 65% Fe
• Current programme: 2011 drilling campaign underway (25,000m)
• Potential for direct shipping ore ("DSO") being investigated

 

The Nkout Iron prospect is located in the Company's Djoum licence in southern Cameroon. The project was identified from interpretation of airborne magnetic and remote sensing data in 2006 whilst investigating gold occurrences in the 150km long, Sangemalina-Djoum Archaean greenstone belt originally identified by the BRGM.

 

 

Table 1: Nkout Centre, Mineral Resource Estimate

Notes:

(1) Mineral Resources which are not Mineral Reserves do not have demonstrated economic viability

(2) The effective date of the Mineral Resource is 28 January 2011

(3) The Mineral Resource Estimate for the Nkout deposit was constrained within lithological and grade based solids and within a Lerchs-Grossman optimised pit shell defined by the following assumptions; metal price of USD1.40/dmtu; slope angles of 35º and 44º in the oxide and fresh material; a mining recovery of 97.5%; a mining dilution of 2.5%; a base case mining cost of USD1.40/t and an incremental mine operating costs of USD0.05/t/10 m below the 80 m reference RL and USD0.05/t/10 m above the 80 m reference RL; process operating costs of USD4.39/t crushed DSO, USD2.3/t crushed oxide and USD4.49/t crushed BIF ore; and G&A costs of USD 2.31/t crushed ore.

In total, SRK has estimated an Inferred Mineral Resource for Nkout Project of 1.04 billion tonnes ("Bt") grading 34.2% Fe, 43.0% SiO₂ and 2.9% Al₂O₃ and 0.05% P. Of this, 7 million tonnes ("Mt") grading 58% Fe lies within a near surface high grade oxidized zone (Zone 110, >55% Fe), 22.5 Mt grading 51.2% Fe lies within the oxidized zone 120 (50 to 55% Fe) and 131 Mt lies within the oxidized zone 130 (30 to 50% Fe). 878.6 Mt lies within the fresh magnetite BIF domain (Zone 210) and grades 32.7% Fe.

Nkout Centre Resource Potential

The Nkout Centre model is open at depth and SRK recognises that there is potential to increase the Mineral Resource Statement by targeting material that falls below the optimised pit shell but remains potentially economic. This material, based on a metal price of USD1.40/dmtu is considered by SRK to be potentially economic, should sufficient exploration data be collected that confirms the geometry and continuation of the orebody and that enables a classified resource to be estimated. SRK has identified that an additional 300 to 600 Mt lies below the optimised pit shell used for constraining the Inferred Mineral Resources. The potential quantity of tonnes is conceptual in nature as there has been insufficient exploration or demonstration of economic viability to report these in the Inferred Mineral Resource category at the current time. It is uncertain if further exploration will result in these targets being defined and reported in a future Mineral Resource Estimate. These potential tonnages reflect a range of material within SRK's wireframe solid models outlining the interpreted down dip extent of mineralisation.

Figure 1: Nkout & Ngoa - Total Magnetic Intensity Map

Figure 2: Essong & Djoum Licence - Total Magnetic Intensity Map

 

Database Validation

The QA/QC program for Company's Nkout project consists of alternating the insertion of a blank, standard and duplicate sample on a regular basis within the sample train. The Company uses standards with varying grades which are also alternated. All samples have been assayed at the accredited OMAC laboratory in Ireland. SRK found that the results of the above described QA/QC program indicate that the Company's Nkout assay databases were appropriate for Mineral Resource Estimation.

Data Verification

Howard Baker as qualified person completed the verification of data on which the Nkout Resource Estimate was based. This verification included an assessment of QA/QC data, sample preparation and assay methodologies, density data, data inputs and survey data used in the estimate. Data was validated by using field checks, statistical methods and evaluating the Company's protocols.

Geological Modelling, Resource Estimation Assumptions, Parameters and Methods

Nkout Centre, being a 3.5 km portion of a larger 20 km strike length magnetic anomaly, forms an east-west trending magnetite Banded Iron Formation ("BIF") with an oxidized cap of dominantly haematite mineralisation. SRK created a geological model based on the lithological logging and magnetic susceptibility data enabling the hangingwall and footwall contacts of the BIF unit to modelled and a three dimensional solid to be created. A statistical review of the validated drillhole data enabled grade based domains to be created within the oxidized cap. Internal metasedimentary waste domains created within the BIF and oxidized cap were based on lithology logging, magnetic susceptibility data and predominantly Al₂O_3­ assay grades.

A 5 m composite file was used in a geostatistical study (variography and Quantitative Kriging Neighbourhood Analysis, "QKNA") that enabled Ordinary Kriging ("OK") to be used as the main grade interpolation method. The interpolation used an elliptical search following the predominant dip and dip direction of the geological domains. The results of the variography and the QKNA were utilised to determine the most appropriate search and estimation parameters.

The interpolated block model was validated through visual checks and a comparison of the mean input composite and output model grades. SRK is confident that the interpolated block grades are a reasonable reflection of the available sample data.

Metallurgical Test Work

Metallurgical test work is currently underway on a composite sample of saprolite ore (Zone 120 and 130 combined) from the Nkout Centre project. The test work is being undertaken by SGS Minerals in the UK. The sample is a composite sample with approximately equal proportions of material from three drill line sections drilled during the 2010 programme. Samples were taken from eight drill holes and the target Fe head grade of the sample was 44%, being in-line with the average grade of this domain.

The gravity separation tests showed little potential for lump production; however, the results indicated that the production of a sinter fines product from the saprolite ore has potential. For each size fraction below 3 mm, a high specific gravity ("SG") fraction with an Fe content of the order of 65% Fe or greater was produced, with Fe recoveries in some size fractions exceeding 70%.

While significant further test work is required, the early indications are that the Nkout saprolite presents the potential for the production of a sinter fines product through a flowsheet largely based on gravity separation.

Based on the assay results obtained from the first two completed drillholes, SRK selected 94 representative samples for Davis Tube Testwork (DTT). The DTT results, based on a grind size of P90 less than 100µ, have been reviewed by SRK to evaluate the quality of the Fe concentrate that can be produced from the Nkout Centre project in relation to the feed grade.

The DTT shows that a high grade concentrate averaging greater than 70% Fe can be attained with low levels of contaminants. The mass recovery shows an average of 42.2% and 87% of the Fe relates to a recoverable magnetite mineral phase.

Mineral Resource Classification

The Nkout project has been classified as containing Inferred Mineral Resource in the fresh BIF and oxidised domains. This is mostly due to the wide spaced drilling and the poor geological continuity of the internal metasediments and areas around the interpreted faults. Inferred Mineral Resources have been extrapolated no more than 200 m down dip of the deepest drillhole intersection. It is the opinion of SRK that the down dip extension of Inferred Mineral Resources is justified in areas of unsupported blocks due to the known down-dip extensions as observed through the deep drilling at Nkout that has intersected magnetite BIF up to 390 m from surface.

Archive airborne magnetic data indicates a 10km long, domain change dipole interpreted as an area of highly magnetic rocks likely to host Banded Iron Formation ("BIF") targets in an Archaean setting. The Company considers that the dimensions of Nkout and surrounding hills represent a potentially economic iron deposit.

 

In June 2006, African Aura's 100% owned subsidiary Caminex was awarded the Akonolinga (997km²) and Djoum licences (998km²) which cover the entirety of the 150km long greenstone belt, including Nkout and a number of other targets identified by the Company.

Further iron prospects identified

This phase of reconnaissance mapping and sampling has confirmed four new iron prospects:

Ngoa is approximately 2km long and stands some 100m higher than Nkout. Its flanks are strewn with a high proportion of enriched banded iron formation ("BIF") float with haematite ± magnetite contents visually estimated between 70% and 100%.

The Akom Hills prospects cover a discontinuous strike length of approximately 20km based on interpreted airborne geophysical data. Mapping of the prospects has identified three separate BIF occurrences with a combined strike length of approximately 8km. Samples were collected over these occurrences including an outcrop of iron rich BIF.

 

The town of Djoum is located 280 km SE of Yaoundé, of which 170km is macadam road and 110 km is laterite road. From Yaoundé it takes five to six hours to reach Djoum, via Sangmelina.

The Nkout prospect is strategically well situated close to existing infrastructure in a significant iron ore province which includes Sundance Resources' Mbalam iron deposit located 150km to the south east. The whole province lies within reach of the site of the proposed deep water port at Kribi on the Atlantic coast.

 

 

 

Further information about Putu, Liberia

Overview

Licence: 425 km²
Target: Haematite/Magnetite deposit with potential strike of 12km
Resource: NI 43-101 Inferred resource estimate of 1.07 Bt @ 37.6% Fe from 2.6km of strike
Location: South East Liberia 100km for Atlantic Coast
Status: 4,000m drilling program completed
Current program:27,000m drill programme and airborne survey
Ownership: 38.5% Mano River Iron Ore Holdings, 61.5% Severstal Group

Current Status

In July 2009 SRK Consulting (UK) Ltd was engaged to produce a National Instrument 43-101 (NI43-101) compliant Independent Mineral Resource Estimate for the Putu Iron Ore Project based on previously announced drilling results.

The estimate for the 2.6km section of the 12km ridge drill tested to date provided an initial Inferred Mineral Resource of 1,077 million tonnes at a grade of 37.6% total of Banded Iron Formation (BIF) mineralisation.

Selected results from the 4,000m drilling programme include:

 

• 63.54% Fe (Haematite) over 63.0m
• 54.21% Fe (Haematite) over 54.6m
• 63.60% Fe (Haematite) over 49.5m
• 39.04% Fe (Fresh Magnetite) over 367.4m

The assay data was composited to 5 metres and used in statistical and geostatistical (Variography) studies that enabled Ordinary Kriging (OK) to be applied as the main grade interpolation method.

Putu Range Prospect

SRK has reported the Mineral Resource split into the following material types:

 

This Mineral Resource Statement is presented in Table 1. The statement has been classified in accordance with the Guidelines of National Instrument 43-101 and accompanying documents 43-101.F1 and 43-101.CP.

Table: 1 - Putu Deposit, Initial Mineral Resource Statement

In addition to the Inferred Mineral Resource as quoted above in Table 1, beneath the 300RL, and within the geological model, there is some 364 Mt of magnetite BIF.

Current exploration programme

To date 11 drill holes have been completed to a maximum depth of approximately 400m. The drill holes were positioned to allow for an initial resource estimate and to prove the geological model. Four out of the 11 holes drilled ended whilst still in mineralization. Table 2 shows the drilling results.

Putu Field Camp

Table: 2 - Latest drilling results

Concurrent with the drilling program an historic drilling adit, approximately 300m below the ridge-line and roughly in the middle of the Putu Range was re-opened and made safe. When fully opened the adit was found to be 208m long, samples at 2.0m intervals yielded an average iron content of 42.7% Fe. These samples were also tested for their magnetic susceptibility, a measure of their magnetic iron minerals content (predominantly magnetite; however haematite does have a week magnetic signature). The results along the adit showed a significant increase in the magnetic susceptibility at approximately 66m from the adit mouth indicating the thickness of the overlying haematitic material to be circa 60m at that point. It was noted at the time that the adit was terminated whilst still in mineralised material of interesting grade. Table 3 shows the results from the channel sampling in the adit.

Putu adit

Geological Setting

Sampling and mineralogical analysis completed by Mano indicate that the predominant iron mineral is magnetite-itabirite which is overlain by a substantial layer of haematite-itabirite. The quality of the mineralisation is high and locally very high, with low phosphorous and alumina values, similar in many ways to that of the Bong mine which operated until 1994.

The overlying haematitic material which can produce high grade direct shipping ore with a high lump/fines ratio which will require substantially less energy to produce than the pellets/concentrate that can be produced from the magnetitic material. Planned metallurgical testing will determine the magnitude of this benefit, however if the material is shown to be similar to that at Bong, these benefits could be substantial. The principal gangue material is quartz which is found in both veinlets and a generally coarse grain size which should facilitate its removal during processing.

Infrastructure & Local Resources

Iron ore is a bulk material and the location of the deposit has great influence on the economics of a project. Putu is particularly favourably, situated just over 100km from the Atlantic coast and importantly the terrain between it and the coast gently sloping and is free from any major topographic features.

 

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