The Globe and Mail

Go to the Globe and Mail homepage

Jump to main navigationJump to main content

Press release from CNW Group

Mirabela Nickel Limited - Significant Increase in Santa Rita Open-Pit Resources

Thursday, October 18, 2012

Mirabela Nickel Limited - Significant Increase in Santa Rita Open-Pit Resources21:43 EDT Thursday, October 18, 2012PERTH, Australia, Oct. 19, 2012 /CNW/ - Mirabela Nickel Limited ("Mirabela" or the "Company") (ASX: MBN, TSX: MNB) is pleased to announce a significant increase in Resources after the successful open pit extension drilling program which was completed during the second quarter.The revised remaining Resources as at the 30th September 2012 increased to 204.0 Mt @ 0.49% nickel (Measured, Indicated) and 79.6 Mt @ 0.56% nickel (Inferred), as presented in the table below.  The current mine life of 22 years is based solely on the previously stated Reserves of 159.0 Mt @ 0.52% nickel and 0.14% copper as at the end of December 2010 and a mine rate of 7.2 Mtpa of ore.Santa Rita DepositResources Table - Remaining as of the End of September 2012PitClassificationtonnes (million)Nickel grade (%)Copper grade (%)Open Pit1, 2Measured16.00.500.10 Indicated188.00.490.13 Sub Total204.00.490.12Open Pit1, 2Inferred79.60.560.15Underground3, 4Inferred77.00.780.22     1 Based on a cut-off grade of 0.13% recoverable nickel.2 Remaining as of end of September, 2012.3 Based on a average cut-off grade of 0.50% nickel.4 As of February 2009, re-reported using revised base of pit in October 2012.The completion of the latest resource update is based on recent deeper drilling under the northern zone of Santa Rita, (14 holes for 9,540 metres); a re-interpretation of geology and structure for the entire deposit; and use of Ordinary Kriging for the Block Model, (with no Change of Support applied). The largest increases occurred in the Indicated and Inferred classifications where Resources increased approximately 32 Mt and 54 Mt respectively.  The Underground Inferred Resources decreased by approximately 10 Mt due to some of the Underground Inferred Resource being included within the updated pit shell.The additional drilling brings the total amount of resource drilling specifically for Santa Rita to 675 holes for 190,660 metres.Ian Purdy, CEO and Managing Director, said "This is an excellent result for Mirabela and reinforces the strategic significance of the Santa Rita operation on a global scale.  The increase in Resources provides an excellent platform for the next stage of our operational expansion studies which are currently ongoing".Competent PersonsThe information in this report that relates to the updated October 2012 Mineral Resources for the Santa Rita Nickel Deposit is based on information compiled by Mr. Lauritz Barnes and reviewed by Mr. Doug Corley.Mr Barnes is a Member of the Australian Institute of Geoscientists, and is a Consultant to Mirabela Nickel Limited.Mr Corley is a Member of the Australian Institute of Geoscientists and is a Registered Professional Geoscientist in the field of Mining (Registration Number 10109), and is employed as a Principal Resource Consultant with Coffey Mining Pty Limited.Messrs Barnes and Corley qualify as both a Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' (JORC Code) and as a Qualified Person in accordance with NI 43‐101. Each is independent of Mirabela Nickel Limited within the meaning of NI 43-101. Messrs Barnes and Corley have verified the data underlying the disclosures in this announcement. Messrs Barnes and Corley approve and consent to the inclusion in the presentation of the matters and defined Resources information based on their information in the form and context in which it appears.Appendix 1:  Assessment and Reporting Criteria TablesThe following table provides a summary of important criteria related to the assessment and reporting of the Santa Rita Mineral Resources as presented in Table 1 of the Australian code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC Code, 2004).CriteriaExplanationSampling Techniques and DataDrilling TechniquesAll 675 drillholes used in the Santa Rita resource interpretation areDiamond (predominantly NQ with some HQ and PQ) drillholes for190,660.3m.Drill sample RecoveryDiamond core recovery within the ore averaged 97.6%, with 98.9% ofsamples having a sample recovery greater than 80%.LoggingDiamond core was logged into a validated Excel spread sheet loggingsystem and imported into industry standard drillhole databasemanagement software.All core was photographed, logged, cut, sampled and is stored atMirabela's exploration office and core shed in Ipiau, Bahia State, Brazil(within 5 km of the Santa Rita mine).Sampling techniquesand preparationCore is oriented along the bottom of the hole. All samples were takenas half core using a diamond core saw.Quality of assay dataand laboratory testsQuality control for all drilling was carried out involving certifiedreference standards, field and coarse crush duplicates and blanksamples to monitor the accuracy and precision of the laboratory data.Samples were prepared and ALS Global's facility in Belo Horizonte,Minas Gerais State, Brazil.  Analyses were determined using 4 Aciddigest ICP Atomic Emission Spectrometry by ALS Global's ISO9001:2000 accredited laboratories in Vancouver (Canada), Perth(Australia) and Lima (Peru).  All samples returning nickel grades greaterthan 0.6% from the ICP-AES method were re-analysed using ALS'sspecific ore grade method.  Platinum, palladium and gold grades weredetermined by 30g Fire Assay with ICP-MS finish by ALS in Vancouver,Perth and Lima.Verification ofsampling and assayingUmpire assay checks were also completed by ACME AnalyticalLaboratory Ltd (ISO 9001:2000 accredited) in Vancouver, Canada, andUltra Trace Analytical Laboratories (ISO 17025 accredited), in Perth,Australia.Location of DataPointsAll diamond drillholes have been located by DGPS with a horizontalaccuracy of +/-0.5m and a vertical accuracy of +/-1m, and subsequentlysurveyed by contract and/or Mirabela surveyors.All holes had magnetic downhole surveys taken initially at 10mdownhole - and then at approximately 30m intervals. For qualitycontrol purposes, approximately 100 holes were also surveyed post-drilling by Downhole Surveys DHS Pty Ltd. using a north-seekinggyroscope. The initial magnetic downhole surveys were checkedagainst the gyroscope results with all matching to acceptable standard.Data Spacing anddistributionDrilling has been completed on nominal east-west sections with 40-60m spacing to support Indicated resource classification.  In areas, infillhas been completed to 20-25m spacing to support Measured resourceclass and more open spacing 100-120m spacing in the deeper partssupporting Inferred resources.Data Spacing anddistributionThe vast majority of the drilling was angled to intersect perpendicularto the trend of the geology and mineralised zone.  Roughly 10% of thedrillholes were drilled at other orientations for geotechnical,metallurgical sampling or for testing geological and mineralisationcontinuity.Estimating and Reporting of  Mineral ResourcesConstruction ofgeological, structuraland mineralisationmodelsA 3-D model has been constructed using industry standard resourcemodelling software.  Lithological contracts, faults, dolerite dykes andthe mineralised zone were all modelled into 3-D wireframes then usedto populate the block model and flag the mineralised zone compositesfor use in the estimation process.Estimation andmodelling techniquesOrdinary Kriging (OK) to the parent block size (20mE x 25mN x 5mRL)was used to estimate Ni, Cu, Co, Pd, Pt, Au, Fe, Mg and S, based on 3mcomposited drill hole grades. A recoverable Ni attribute (NiRec)calculated for each composite using a regression equation establishedfrom plant operating data was also estimated.All data was transformed into "flattened space" where the OK estimatewas conducted.  The estimated blocks were then transformed back intotheir original spatial location, for reporting purposes.Three estimation passes were used for all elements with distance limitsof 40m, 80m and 160m consecutively.  A maximum of 24 samples andminimum of 8 samples of which no more than 5 were from any onehole was used for each pass. For all estimations a discretisation matrixof 3x3x3 was used.MoistureTonnes have been estimated on a dry basis.Cut-off parametersMineral Resources have been reported using a recoverable nickel cut-off of 0.13%. Mining factors orassumptionsNo mining assumptions have been built into the resource.Metallurgical factorsor assumptionsNo metallurgical factors or assumptions have been built into theresource.Bulk density16,726 core samples have been measured for density from thedrillholes used in the modelling and resource estimation.The method used the air dried half core sample weighed in air andthen when immersed in water, the results of which were used toestimate the density.Samples were selected from the oxide zone through to the fresh zonewith wax coating methods applied where necessary to core samples toensure representative results.ClassificationMineral Resources have been classified on the basis of confidence inthe geological and grade continuity using the drilling density, geologicalmodel and pass in which the nickel was estimated.Measured Resources have been defined generally in areas of 20m to25m drill spacing and in Pass 1.Indicated Resources have been defined generally in areas of 40m to60m drill spacing and in Pass 2.Inferred Mineral Resources have been defined generally in areas of100m to 120m drill spacing and in Pass 3.Block ModelVerificationSwath plots were generated along east-west and elevation sectionsand the block grades compared well with the composite grades. Visual3D comparisons were also completed with the estimated blocks andcomposited drillhole data, to check that the continuity and grade wasreflected in the estimated blocks. Audits or reviewsA high level audit of the interpretation, compositing, top cuts,estimation modelling parameters and classifications was carried out byCoffey Mining. No matters were noted that would impair the validity ofthe Mineral Resource Estimate.  SOURCE: Mirabela Nickel Ltd.For further information: Bill Bent, Chief Development Officer Mirabela Nickel Limited Telephone: +61 433 790 070 billb@mirabela.com.au