SECTION 1 SAMPLING TECHNIQUES AND DATA

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1 Silvergrass East Table 1 The following table provides a summary of important assessment and reporting criteria used at Silvergrass East for the reporting of Mineral Resources and Ore Reserves in accordance with the Table 1 checklist in The Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (The JORC Code, 2012 Edition). Criteria in each section apply to all preceding and succeeding sections. SECTION 1 SAMPLING TECHNIQUES AND DATA Criteria Sampling techniques Commentary Samples for geologic logging and assay are collected on 2 m intervals using percussion and reverse circulation drilling methods. Diamond core drilling was performed to collect samples for geotechnical testing (HQ, 63.5 mm diameter) and metallurgical testing (PQ, 85 mm diameter). Drilling techniques Drill sample recovery Drilling is predominantly by reverse circulation with lesser percussion and diamond drill core. Refer to Section 2: Drill Hole Information for a detailed breakdown of drilling by type and year. No direct recovery measurements of reverse circulation samples are performed. Sample weights are recorded from laboratory splits and the recovery at the rig is visually estimated for loss per 2 m drilling interval. Diamond drill core recovery loss of 5 cm or greater is recorded by the driller. Overall recovery from diamond drill core exceeded 92% at Silvergrass East. Logging Standardised Rio Tinto Iron Ore logging systems are utilised for all drilling. Geologic and material type logging was performed on 1.5 m intervals for reverse circulation drilling until the 1990 s and at 2 m intervals thereafter. Intervals are logged at 2 m for all diamond core drilling. All drill holes since 1997 are logged using downhole geophysical tools for gamma trace, calliper, gamma density, resistivity, magnetic susceptibility, and magnetic deviation. Since 2008, all geotechnical drill holes are logged using an acoustic televiewer for structural data measurements. Sub-sampling techniques and sample preparation Sub-sampling (pre-1978): All sub-sampling for percussion drilling occurred at the rig. Methods were not documented. Sub-sampling ( ): Samples were split through a Jones multi-level riffle splitter, dividing the samples into three portions. Sub-sampling (post-1997): All reverse circulation drilling utilises the Rotating Cone Splitter (RCS) sampling system as per industry standards. Sample preparation: The sample is oven dried at 105 degrees Celsius for a minimum of 24 hours. The sample is then crushed to approximately 3 mm using a Jaw Crusher and split to produce a 500 g subsample. The sub-sample is pulverised to 95% of weight passing 150 μm. Assay methods: All assaying of samples used in Mineral Resource estimates have been performed by independent, National Association of Testing Authorities (NATA) certified laboratories. Fe, SiO 2, Al 2 O 3, P, Mn, MgO, TiO 2, CaO and S are assayed using Industry standard Lithium metaborate fusion and X-Ray Fluorescence (XRF) analysis. Loss on Ignition (LOI) is determined using industry standard Thermo-gravimetric analyser (TGA). Quality of assay data and laboratory tests Standardised Rio Tinto Iron Ore quality control procedures are in place for all drilling, post Prior to then, no quality control documentation is available. Field standards and field duplicates are systematically used. Laboratory preparation duplicates and assay duplicates are also included in the quality assurance and quality control protocol. Statistical analyses indicate a high level of precision and accuracy. Analyses of the duplicate dataset do not detect any bias in the field duplicate data. Verification of sampling and Several drill holes from the 1970 s and 1980 s were re-drilled between 2008 and 2009 showing adequate reproducibility between historic and modern methods. 1

2 assaying Comparison of reverse circulation and twinned diamond drill core assay data distributions show that the drilling methods have similar grade distributions verifying the suitability of reverse circulation samples in the Mineral Resource estimate. Location of data points All drill hole collar locations at the Silvergrass East deposit are surveyed to Geocentric Datum of Australia 1994 (GDA94) grid by Rio Tinto Iron Ore evaluation surveyors using Differential Global Positioning System survey equipment. Drill hole collar reduced level (RL) data is compared to detailed topographic maps and show that the collar survey data is accurate. The topographic surface is based on 10 m grid sampling of the 2012 Light Detecting and Ranging (LiDAR) survey, including spot heights from DGPS drilling collars and is considered robust. Data spacing and distribution Drill hole spacing is predominately 50 m 50 m. 200 m 50 m spacing drilling was performed on the eastern and western deposit extents. Dedicated geotechnical drilling has been completed to intersect planned final pit walls. Orientation of data in relation to geological structure Drill lines lie north to south along the GDA94 grid and perpendicular to the deposit strike. Drilling is predominantly vertical however angled holes were drilled in areas with restricted access or to intersect structures perpendicular to strike. Sample security Laboratory samples (A splits) are collected by field assistants, placed onto steel sample racks, and transported by Centurion trucks to Ultra Trace Laboratories in Perth, Western Australia for analyses. Retention samples (B splits) are collected and stored in drums for 2 years at the Evaluation camp located on-site. Assay pulps are retained indefinitely at Rio Tinto Iron Ore facilities located at either Pannawonica or Dampier. Audits or reviews No external audits have been performed. Internal Rio Tinto Iron Ore peer review processes and internal Rio Tinto technical reviews have been completed. These reviews concluded that the fundamental data collection techniques are appropriate. SECTION 2 REPORTING OF EXPLORATION RESULTS Criteria Mineral tenement and land tenure status Commentary 100% owned by Hamersley Iron Proprietary Limited (100% Rio Tinto Limited), held under Mining Lease (ML) 4SA Sections 265, 266 and Mining Lease (ML) 272SA Section 003. This deposit was previously held under Temporary Reserves 5587H, 5562H, 5563H and 5728H. Exploration done by other parties Temporary reserve (TR) 5587H was granted to Hancock Prospecting Proprietary Limited (Hancock) and Wright Prospecting Proprietary Limited (Wright) in In 1975, Texas Gulf Australia became a joint venture partner with Hancock and Wright and undertook evaluation work on the temporary reserve. A variation agreement to the Iron Ore (Wittenoom) Agreement (IOWA) between these joint venturers and the Western Australian State government was signed in In 1981, Texas Gulf Australia sold the rights in the temporary reserve to a subsidiary of Conzinc Riotinto of Australia Limited (CRA), which was later renamed as Hamersley Iron Proprietary Limited (HI). In 1991, an agreement between HI, Hancock, and Wright to purchase Hancock and Wright s share to the IOWA was concluded. Then in 1992, a variation to the IOWA was passed through the Western Australian State parliament whereby TR5587 was transferred from the IOWA to the Iron Ore (Hamersley Iron) State Agreement and incorporated into Mining Lease (ML) 272SA. Geology The deposit type is a bedded iron ore deposit hosted in the Archean Marra Mamba Iron Formation and the West Angelas Member of the Wittenoom Formation. The style of mineralisation is consistent with other Marra Mamba-hosted iron deposits located in the Pilbara region, Western Australia. 2

3 Drill hole Information Data aggregation methods Drilling Data Summary Table 1: Drilling Data Summary Year Diamonds Reverse Circulation Percussion # Holes Metres # Holes Metres # Holes Metres * 1, * 2, * 3, ** * * * * 1, * 3, ** * 1, * 56, ** * 53, ** 2, * 1,345 61* 4, * 2, ,808 Total 91* 8,143 2,601* 162, * 8,180 *One or more holes excluded from estimation. **Entire program excluded from estimation. The data had been composited to 2 m for Mineral Resource estimation. No maximum or minimum grade truncations were performed. Cut-off grade for High-Grade ore is greater than or equal to 58% Fe. Relationship between mineralisation widths and intercept lengths Diagrams Downhole lengths are reported which are essentially true width due to predominantly vertical drilling and gently folded, horizontal strata. In areas where the strata steepen, angled drill holes were completed. True width of mineralised intercepts is held consistent during geologic interpretations. 3

4 Balanced reporting Other substantive exploration data Not applicable. Rio Tinto Iron Ore has not specifically released exploration results for these deposits. A program of diamond drill core (PQ) metallurgical drilling has been completed to collect samples for metallurgical testing. Downhole gamma-gamma data has been collected for in situ bulk density data. This has been calibrated using a program of diamond drill core (HQ) across the deposits. Geologic surface mapping data has been collected across the Silvergrass East area in 2008 at the 1:10,000. 4

5 Further work Further infill reverse circulation drilling is planned at 50 m 50 m spacing. SECTION 3 ESTIMATION AND REPORTING OF MINERAL RESOURCES Criteria Database integrity Commentary All drilling data is securely stored in an AcQuire geoscientific information management system managed by a dedicated team within Rio Tinto Iron Ore. The system is backed up nightly on servers located in Perth, Western Australia. The backup system has been tested in 2013, demonstrating that the system is effective. The drilling database used for Mineral Resource estimation has been internally validated by Rio Tinto Iron Ore personnel. Site visits The Competent Person visited Silvergrass East in Geological interpretation Geological modelling is undertaken by Rio Tinto Iron Ore senior geologists. The method involves interpretation of downhole stratigraphy using surface geologic mapping, lithological logging data, downhole gamma data, and assay data. Cross-sectional interpretation of each stratigraphic unit is performed followed by interpretation of mineralisation and hydration boundaries. Three-dimensional wireframes of the sectional interpretations are created to produce the geological model. Dimensions The deposit trends 7km east to west and varies between 200 m to 3 km north to south. The deposit extends to a depth of 300 m below the topographic surface. Estimation and modelling techniques The block model is aligned to the GDA94 grid. Block size is 25 m E 25 m N 5 m RL for parent blocks. Parent blocks are sub-celled to the geological boundaries to preserve volume. Mineralised domains are estimated by ordinary kriging and non-mineralised domains are estimated by inverse distance weighting to the first power. The estimated model was validated using a combination of visual, statistical and Multivariate Global Change of Support techniques. There is no production data to reconcile model quality. Moisture All Mineral Resource tonnages reported on a dry basis. Cut-off parameters Mining factors or assumptions Metallurgical factors or assumptions Environmental factors or assumptions The basis for the adopted cut-off grade is determined by Rio Tinto Iron Ore marketing teams to ensure the product meets internal specifications. The cut-off grade for high-grade Marra Mamba ore is greater than or equal to 58% Fe. Development of this Mineral Resource estimate assumes mining using standard Rio Tinto Iron Ore equipment. The assumed mining method is conventional truck and shovel open pit mining with 10 m benches. Mining practices will include detailed grade control utilising blast hole data. It is assumed that wet screening processes used by Rio Tinto Iron Ore will be applicable for the processing of the Silvergrass East deposit. Rio Tinto Iron Ore has an extensive environmental and heritage approval process. A detailed review of these requirements has been undertaken in a recent Pre-Feasibility Study and pending Feasibility Study. No issues were identified that would impact on the Mineral Resource estimate. Bulk density Dry bulk density was estimated using accepted gamma-density data collected at 10 cm intervals from downhole geophysical sondes. Accepted gamma-density data is corrected for moisture using diamond drill core specifically drilled throughout the deposit. Bulk density was estimated using ordinary kriging in mineralised zones and inverse distance weighted to the first power in non-mineralised zones. Classification The Mineral Resource includes the classifications: Measured, Indicated, and Inferred with additional material (greater than 50% Fe) set as unclassified. The Silvergrass East deposit is predominantly Measured Mineral Resources. The Competent Person is satisfied that the stated Mineral Resource classification reflects the geological controls interpreted and the estimation constraints of the deposits. Audits or All stages of Mineral Resource estimation have undergone an internal peer review process, 5

6 reviews Discussion of relative accuracy/ confidence which has documented all phases of the process. The Mineral Resource estimate has been accepted by the Competent Person. Rio Tinto Iron Ore operate multiple mines in the Pilbara region of Western Australia. The Mineral Resource data collection and estimation techniques used for the Silvergrass East deposit are consistent with those applied at other deposits which are being mined. Reconciliation of actual production with the Mineral Resource estimates for the existing operational deposits are generally within five percent for tonnes and grade. This result is indicative of a robust process. Accuracy and confidence of Mineral Resource estimation is consistent with the current level of study (Feasibility Study). SECTION 4 ESTIMATION AND REPORTING OF ORE RESERVES Criteria Mineral Resource estimate for conversion to Ore Reserves Commentary Ore reserve estimates in the 2013 Feasibility Study are based on a mineral resource estimate completed in March Where applicable the most recent Mineral Resource estimate was used for reporting Ore Reserves with previously defined pit designs. These were validated for economic viability. Mineral Resources are reported additional to Ore Reserves. Site visits The Competent Person visited Silvergrass East in Study status The reportable Ore Reserve is based on the Silvergrass East Feasibility Study which was finalised in Cut-off parameters Mining factors or assumptions Metallurgical factors or assumptions The cut-off grade for high-grade Marra Mamba ore is greater than or equal to 58% Fe. The Mineral Resource model was regularised to a block size of 12.5 m E 12.5 m N 5 m RL which was determined to be the selective mining unit following analysis of a range of selective mining unit options. Dilution and mining recovery were modelled by applying the regularisation process to the sub-block geological model. Pit optimisations utilising the Lerchs-Grosmann algorithm with industry standard software were undertaken. This optimisation utilised the regularised resource together with cost, revenue and geotechnical inputs. The resultant pit shells were used to develop detailed pit designs with due consideration of geotechnical, geometric and access constraints. These pit designs were used as the basis for production scheduling and evaluation purposes. Conventional mining methods (truck and shovel) similar to other Rio Tinto Iron Ore mines were selected. It is proposed to crush the material at Silvergrass East and convey it to a central processing facility at the Rio Tinto Nammuldi Iron Mine. The geotechnical parameters have been derived following geotechnical studies informed by 45 diamond drill holes specifically drilled for geotechnical purposes on the surrounding host rock. The resultant inter ramp slope angles vary between 13 and 46 degrees depending on the local rock mass and structural geological conditions. During the above process Inferred Mineral Resources were excluded from mine schedules and economic valuations utilised to validate the economic viability of Ore Reserves. During drill campaigns in 1998, 2008 and 2010, 660 m of metallurgical diamond core (PQ) were recovered in Silvergrass East. Data obtained from this core formed the basis for characterisation test work which informed the Preliminary Engineering Study for the design of the processing facility. The map below show the location of these drill holes. The diamond drill core test results were utilised to develop metallurgical models representing different metallurgical domains which were considered representative of the ore body. The metallurgical models predict product tonnage and grade parameters for lump and fines products. Wet processing is proposed for Silvergrass East with the Marra Mamba ore de-slimed in order to improve handling characteristics and to increase product grades. The average total product recovery modelled for the deposit is ~93%. 6

7 Environmental The Silvergrass East project was referred to the Environmental Protection Authority under section 38 of the Environmental Protection Act 1986 in 2010, as part of the Nammuldi- Silvergrass Expansion project. The Proposal was formally assessed at the level of Public Environmental Review and the Minister for Environment authorised implementation of the proposal via Ministerial Statement in The proposal was not referred under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999 after it was determined in 2010 to be unlikely to have a significant impact on any matters of national environmental significance, after applying the Commonwealth Significant Impact Guidelines 1.1. A geochemical risk assessment for the project has been undertaken. The assessment encompasses all material types present at the site, and tests have been conducted in accordance with the Global Acid Rock Drainage Guide. Mining operations at the project pose a low acid mine drainage risk based on current pit shell designs and the assessment of samples from within the Project pit shells. Infrastructure General access to Silvergrass East will be via an extension of the Nammuldi Mine access road with an additional access to be constructed from the Brockman 4 to Brockman 2 road. Silvergrass East will utilise facilities at the Nammuldi Mine including product stockpiles, rail and train load-out system. Ore will be railed to Rio Tinto s ports at Dampier and Cape Lambert. Upon completion of current and planned/approved construction projects, the port and railway networks will have sufficient capacity to accommodate ore supply from Silvergrass East. Centrally located facilities will service both Nammuldi and Silvergrass East. These include: HME workshop and wash down, bulk lubricant, tyre change, and a fabrication workshop. Dewatering infrastructure, including a total of 21 bores, will feed water into an expanded irrigated agricultural area in addition to satisfying site water demand. Surface water management structures including diversion channels and bunds will be constructed to protect mining areas. Primary crushed ore from Silvergrass East will be transported to an expanded Nammuldi below water table (NBWT) wet process plant via a 9 km overland conveyor. The wet processing facility will include scrubbing, wet screening, classification and filtration circuits. Waste fines will be thickened and disposed in a waste fine storage facility. Fuel will be supplied via the rail fuel hub being constructed approximately 10 km south of the NBWT project. Bulk fuel storage and refuelling facilities will be provided on site. Supply of ammonium nitrate and fuel oil (ANFO) will be accessed from the combined NBWT/Silvergrass East explosives facility, transported by way of the Brockman 4 to Brockman 2 road. Electric power will be supplied to Silvergrass East from the Rio Tinto transmission network linking the existing Brockman 220 kv transmission line. 7

8 Fly-in, Fly-out (FIFO) personnel access will be via the all-weather Boolgeeda air strip and Brockman 4 to Brockman 2 road. Silvergrass East personnel will be housed in the existing Brockman 2 camp. Costs The capital costs are based on a Preliminary Engineering Study utilising experience from the construction of existing similar Rio Tinto Iron Ore projects in the Pilbara, Western Australia. Operating costs were benchmarked with similar operating Rio Tinto Iron Ore mine sites. Exchange rates were forecast by analysing and forecasting macro-economic trends in the Australian and World economy. Transportation costs were based on existing operating experience at Rio Tinto Iron Ore mine sites in the Pilbara, Western Australia. Allowances have been made for royalties to the Western Australian government and other private stakeholders. Revenue factors Rio Tinto applies a common process to the generation of commodity prices across the group. This involves generation of long-term price curves based on current sales contracts, industry capacity analysis, global commodity consumption and economic growth trends. In this process, a price curve rather than a single price point is used to develop estimates of mine returns over the life of the project. The detail of this process and of the price point curves is commercially sensitive and is not disclosed. Market assessment The supply and demand situation for iron ore is affected by a wide range of factors, and as iron and steel consumption changes with economic development and circumstances. Rio Tinto Iron Ore delivers products aligned with its Mineral Resources and Ore Reserves, these products have changed over time and successfully competed with iron ore products supplied by other companies. Economic Economic inputs such as foreign exchange rates, carbon pricing, and inflation rates are also generated internally at Rio Tinto. The detail of this process is commercially sensitive and is not disclosed. Sensitivity testing of the Silvergrass East Ore Reserves using both Rio Tinto long-term prices and a range of published benchmark prices demonstrates a positive net present value for the project sufficient to meet Rio Tinto Limited investment criteria. Social The Silvergrass East is located within Mining Lease (ML) 4SA sections 265 and 266 and Mining Lease (ML) 272SA section 003 which have been granted pursuant to the Iron Ore (Hamersley Range) Agreement Act The Silvergrass East mine and associated infrastructure fall within the area of the Eastern Guruma group s registered native title claim. Rio Tinto Limited and the Eastern Guruma people have a comprehensive relationship that has been documented in an Indigenous Land Use Agreement. Ethnographic and archaeological surveys have been conducted covering the Silvergrass East deposit and proposed infrastructure corridor which have identified several heritage sites; some of which are of extremely high importance to the local Traditional Owners. The sites of highest importance have been excised from the project impact area and, where possible, the other sites have been avoided during planning of the mine and infrastructure. Rio Tinto Iron Ore has completed biological surveys across the project area to support the development of the Silvergrass East project including flora and vegetation and terrestrial and subterranean fauna surveys and aquatic habitats. A number of native vegetation clearing permits have been granted by the Western Australian Department of Mines and Petroleum to allow for preliminary works such as sterilization drilling, geotechnical investigations and mineral exploration. The Silvergrass East project is located within the Shire of Ashburton and Rio Tinto Iron Ore has well established engagement frameworks with the Shire of Ashburton which includes scheduled meetings and project updates. Other Semi-quantitative risk assessments have been undertaken throughout the Silvergrass East study area. No material naturally occurring risks have been identified through the above mentioned risk management processes. Classification The Ore Reserves consist of 77% Proven Reserves and 23% Probable Reserves. The Competent Person is satisfied that the stated Ore Reserve classification reflects the outcome of technical and economic studies. Audits or No external audits have been performed. Internal Rio Tinto Iron Ore peer review processes and internal Rio Tinto technical reviews 8

9 reviews Discussion of relative accuracy/ confidence have been completed. These reviews concluded that the fundamental data collection techniques are appropriate. Rio Tinto Iron Ore operates multiple mines in the Pilbara region of Western Australia. The Ore Reserve estimation techniques utilised for the Silvergrass East deposit are consistent with those applied at the existing operations. Reconciliation of actual production with the Ore Reserve estimate for the existing operations is generally within 5 percent for tonnage and grade. This result is indicative of a robust Ore Reserve estimation process. Accuracy and confidence of modifying factors are generally consistent with the current level of study (Feasibility Study). 9