Mirabela Nickel Limited - Significant Increase in Santa Rita Open-Pit Resources
PERTH, 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 Deposit Resources Table - Remaining as of the End of September 2012 | ||||
| Pit | Classification | tonnes (million) | Nickel grade (%) | Copper grade (%) |
| Open Pit1, 2 | Measured | 16.0 | 0.50 | 0.10 |
| Indicated | 188.0 | 0.49 | 0.13 | |
| Sub Total | 204.0 | 0.49 | 0.12 | |
| Open Pit1, 2 | Inferred | 79.6 | 0.56 | 0.15 |
| Underground3, 4 | Inferred | 77.0 | 0.78 | 0.22 |
| 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 Persons
The 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 Tables
The 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).
| Criteria | Explanation |
| Sampling Techniques and Data | |
| Drilling Techniques | All 675 drillholes used in the Santa Rita resource interpretation are Diamond (predominantly NQ with some HQ and PQ) drillholes for 190,660.3m. |
| Drill sample Recovery | Diamond core recovery within the ore averaged 97.6%, with 98.9% of samples having a sample recovery greater than 80%. |
| Logging | Diamond core was logged into a validated Excel spread sheet logging system and imported into industry standard drillhole database management software. All core was photographed, logged, cut, sampled and is stored at Mirabela's exploration office and core shed in Ipiau, Bahia State, Brazil (within 5 km of the Santa Rita mine). |
| Sampling techniques and preparation | Core is oriented along the bottom of the hole. All samples were taken as half core using a diamond core saw. |
| Quality of assay data and laboratory tests | Quality control for all drilling was carried out involving certified reference standards, field and coarse crush duplicates and blank samples 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 Acid digest ICP Atomic Emission Spectrometry by ALS Global's ISO 9001:2000 accredited laboratories in Vancouver (Canada), Perth (Australia) and Lima (Peru). All samples returning nickel grades greater than 0.6% from the ICP-AES method were re-analysed using ALS's specific ore grade method. Platinum, palladium and gold grades were determined by 30g Fire Assay with ICP-MS finish by ALS in Vancouver, Perth and Lima. |
| Verification of sampling and assaying | Umpire assay checks were also completed by ACME Analytical Laboratory Ltd (ISO 9001:2000 accredited) in Vancouver, Canada, and Ultra Trace Analytical Laboratories (ISO 17025 accredited), in Perth, Australia. |
| Location of Data Points | All diamond drillholes have been located by DGPS with a horizontal accuracy of +/-0.5m and a vertical accuracy of +/-1m, and subsequently surveyed by contract and/or Mirabela surveyors. All holes had magnetic downhole surveys taken initially at 10m downhole - and then at approximately 30m intervals. For quality control purposes, approximately 100 holes were also surveyed post- drilling by Downhole Surveys DHS Pty Ltd. using a north-seeking gyroscope. The initial magnetic downhole surveys were checked against the gyroscope results with all matching to acceptable standard. |
| Data Spacing and distribution | Drilling has been completed on nominal east-west sections with 40- 60m spacing to support Indicated resource classification. In areas, infill has been completed to 20-25m spacing to support Measured resource class and more open spacing 100-120m spacing in the deeper parts supporting Inferred resources. |
| Data Spacing and distribution | The vast majority of the drilling was angled to intersect perpendicular to the trend of the geology and mineralised zone. Roughly 10% of the drillholes were drilled at other orientations for geotechnical, metallurgical sampling or for testing geological and mineralisation continuity. |
| Estimating and Reporting of Mineral Resources | |
| Construction of geological, structural and mineralisation models | A 3-D model has been constructed using industry standard resource modelling software. Lithological contracts, faults, dolerite dykes and the mineralised zone were all modelled into 3-D wireframes then used to populate the block model and flag the mineralised zone composites for use in the estimation process. |
| Estimation and modelling techniques | Ordinary 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 3m composited drill hole grades. A recoverable Ni attribute (NiRec) calculated for each composite using a regression equation established from plant operating data was also estimated. All data was transformed into "flattened space" where the OK estimate was conducted. The estimated blocks were then transformed back into their original spatial location, for reporting purposes. Three estimation passes were used for all elements with distance limits of 40m, 80m and 160m consecutively. A maximum of 24 samples and minimum of 8 samples of which no more than 5 were from any one hole was used for each pass. For all estimations a discretisation matrix of 3x3x3 was used. |
| Moisture | Tonnes have been estimated on a dry basis. |
| Cut-off parameters | Mineral Resources have been reported using a recoverable nickel cut- off of 0.13%. |
| Mining factors or assumptions | No mining assumptions have been built into the resource. |
| Metallurgical factors or assumptions | No metallurgical factors or assumptions have been built into the resource. |
| Bulk density | 16,726 core samples have been measured for density from the drillholes used in the modelling and resource estimation. The method used the air dried half core sample weighed in air and then when immersed in water, the results of which were used to estimate the density. Samples were selected from the oxide zone through to the fresh zone with wax coating methods applied where necessary to core samples to ensure representative results. |
| Classification | Mineral Resources have been classified on the basis of confidence in the geological and grade continuity using the drilling density, geological model and pass in which the nickel was estimated. Measured Resources have been defined generally in areas of 20m to 25m drill spacing and in Pass 1. Indicated Resources have been defined generally in areas of 40m to 60m drill spacing and in Pass 2. Inferred Mineral Resources have been defined generally in areas of 100m to 120m drill spacing and in Pass 3. |
| Block Model Verification | Swath plots were generated along east-west and elevation sections and the block grades compared well with the composite grades. Visual 3D comparisons were also completed with the estimated blocks and composited drillhole data, to check that the continuity and grade was reflected in the estimated blocks. |
| Audits or reviews | A high level audit of the interpretation, compositing, top cuts, estimation modelling parameters and classifications was carried out by Coffey Mining. No matters were noted that would impair the validity of the Mineral Resource Estimate. |
SOURCE Mirabela Nickel Ltd.
Bill Bent, Chief Development Officer
Mirabela Nickel Limited
Telephone: +61 433 790 070
billb@mirabela.com.au
