La red de carreteras

Sampling methodology and approach for Rio Tinto drilling and Norsemont 2005 drilling was detailed in the McCrae (2006) Technical Report. Sampling methodology and approach for Norsemont 2006 to March 2007 drilling was detailed in the Snowden (2007) Technical Report.

GRD Minproc has reviewed the methods used in previous drill programs and considers them appropriate for a Mineral Resource Estimate.

12.1 DRILLHOLE SAMPLING METHODS NORSEMONT 2007-2008 12.1.1 Sample collection

Core trays are delivered to the core facility at the camp site where they are digitally photographed and marker blocks and depths checked. A technician records geotechnical measurements. Gross geological intervals are logged. Preliminary 2 m sample breaks are marked, with the geologist deciding on smaller intervals to coincide with geological features where necessary. A minimum sample length of 0.3 m has been specified.

Sample numbers are assigned, and then detailed lithological and mineralogical logging takes place. Cut lines are marked on the core by the geologist. For heavily fractured core, a steel bar is used as a divider. The same side of the core is always taken for the sample. Samples for density measurement in each major rock unit are extracted at this stage, at approximately 50 m intervals.

Samples are transferred to technicians for splitting into two halves by diamond saw.

QAQC control for the project requires the provision of field duplicates. These are obtained by cutting the required samples into quarters. All samples (one half core, two quarter core) are left in the box for the samplers to collect. This takes place in a separate work area; split core is then returned for placement in canvas bags, tagging (inside and out) and weighing. Blank, standard and duplicate samples are inserted, and sample bags are then packed into larger bags for transport.

The remaining half core is separately stored, with security guards on site 24 hours a day. Samples are securely stored before being loaded onto covered and secured trucks. Samples were transported on a regular basis to the ALS Chemex shipping point at Arequipa until June 2008, and since July 2008 to date samples have been sent to the SGS shipping point (also in Arequipa) where they are transferred to authorised trucks for shipment to the laboratory in Lima. Chain of custody documents with signatures of delivering and receiving parties and the names of persons accompany the samples at all times.

Sampling information, including date, hole, sample interval, sample ID, sample type, QAQC type and sampler is entered on site into Excel spreadsheets, which are ultimately transferred to the database.

12.1.2 Drillhole logging

The core is geologically and geotechnically logged by site-based geologists, using standard terminology and procedures, which were put in place in October 2006. Previous drillholes (including Rio Tinto holes) have been re-logged and re-coded.

Core logging takes place in a sheltered and comfortable core shed, with sufficient space to lay out core trays for several holes. Core logging includes:

 Drillhole summary information, e.g. project details, hole number, logged by, collar coordinates, azimuth and dip, downhole survey information, geological summary and other relevant comments.  A geotechnical log with interval, recovery, RQD, fracture type and fill, frequency, shape,

roughness, intensity, width, angle and details of lost core.

 Lithology, alteration, mineralisation and structure – type, association, intensity and proportion are recorded for each category.

 Sampling details with sample interval and number, and QAQC sampling information.

Data is logged on paper and then entered by hand on site into standardised Excel spreadsheets. Transcription checks are made by Norsemont on one in every 10 records. Data is finally uploaded into a custom-designed Access database in Lima, where further validation and integrity checks are carried out. Only one senior geologist has access to and can change the primary database.

Paper logs are periodically photo-copied; originals are retained on site, with copies being sent to the Norsemont office in Lima.

12.1.3 Density measurements

A total of 1247 density measurements have been made for core from the Constancia-San José area. The density measurements are conducted by ALS Chemex and are representative of the different rock and mineralisation domains recognised to date.

12.1.4 Sample preparation, analysis and security

Sample preparation and assaying for Norsemont was carried out by ALS Chemex in Peru until June 2008, after which SGS del Peru continued with this work. Both laboratories are Peru-based registered laboratories, conforming to ISO 9000 and ISO 9001 standards, respectively.

Samples are prepared and analysed in Lima following standard procedures. Samples are routinely analysed for gold (Fire Assay, AAS finish, 30 g charge) and 41 elements by ICP (HNO3-HClO4-HF-HCl

digestion, HCl Leach). Samples above detection limit are analysed by AAS. All samples with copper values above 0.2% are analysed by a Sequential Copper Method. Analytical data is delivered electronically by the laboratory in Norsemont’s format, and is input directly into the company database.

12.2 CORE SAMPLING

Individual samples respect geological/mineralogical/structural boundaries, and are generally collected at 2 m intervals. Minimum core length has been established at 30 cm, and the maximum is 3 m. The shortest sample recorded is 0.35 m (CO-06-094) and the longest is 4 m (CO-05-035). Three core saws are used, working two 12 hours shifts when required.

The saw facilities are spacious and allow easy handling of the core boxes, which are stored in order before starting the shift. Each saw has a table besides it where the box containing the core to be cut is deposited. Each piece of core is cut along the centre line and, in cases where the core is disaggregated or is easily broken it is wrapped in plastic adhesive tape to facilitate handling. The cut core is then moved to the other side of the room.

QAQC control for the project requires the provision of field duplicates. These are obtained by cutting the required samples into quarters. All samples (one half core, two quarter core) are left in the box for the samplers to collect.

When a number of boxes have been cut they are re-arranged by number and taken out of the saw shed for sampling. Samplers have been instructed always to take the same side of the core samples. The left half is placed in the pre-numbered canvas bag. Long core pieces are broken to fit in the bag. The sample number is written with black, waterproof marker on both sides of the bag, and one of the sample tags is placed in the sample bag.

A written record is kept indicating the drillhole, and the start and end metreage for every shift.

12.3 QAQC PROCEDURES

The Norsemont QAQC procedures include the use of field duplicates, certified standards and blanks. The sample numbers are selected randomly before sampling the core. The sample tickets are appropriately marked and the sample tags ripped off so as to avoid any confusion. All control samples are collected and inserted during the core sampling process.

12.3.1 Field duplicates

Field duplicates are obtained by splitting half core samples, obtaining two quarter core sub-samples, one quarter representing the original sample and the other quarter representing the duplicate sample. These samples are collected to assess the homogeneity of the mineralisation and sampling precision. Field duplicates are inserted by Norsemont at the proportion of 1 in 20.

12.3.2 Blanks

Blanks are introduced at a 1:20 frequency. These samples have been provided by a third laboratory (SGS del Peru) and have been produced from barren material, where particle size is +10 mesh.

Originally (up to drillhole CO-06-062, mid-2006) blanks were obtained on-site from country rocks. However these blanks were not homogeneous and at least one of them had high zinc values, making them unsuitable for quality control.

12.3.3 Standards

Standards (or certified reference materials, “CRM”) are samples with established grades, prepared under special conditions by certified commercial laboratories. The standards for Norsemont have been prepared by SGS in Lima from coarse rejects of previous drilling from Constancia.

Norsemont uses four standard levels, characterised by Cu grades of approximately 2000 ppm, 5000 ppm, 7500 ppm and 25 000 ppm. Three generations of standards have been used in the project. During the first phase, Ag and Zn were not reported for the standards.

The recommended values are summarised in Table 12.1. Table 12.1

Recommended Values for Standards

Period Standard Cu_ppm Mo_ppm Ag_ppm Zn_ppm

GQ601193 2452.4 +/- 122.8 86 +/- 5.5 GQ601194 5165.7 +/- 316.25 319 +/- 22.4 GQ601195 7383.6 +/- 332.8 65 +/- 8.5 May 2006 GQ601196 12 500 +/- 550 159 +/- 8.5 MV600011 2052 +/- 122 74 +/- 5.5 2.3 +/- 0.8 1231 +/- 70 MV600013 5052 +/- 229.5 127 +/- 10 3.5 +/- 1.1 929 +/- 81 MV600014 7503 +/- 215.5 81 +/- 7 4.8 +/- 0.8 1321 +/- 87 November 2006 MV600015 24 476 +/- 899 120 +/- 11 6.4 +/- 1.7 138 +/- 20 MV700038 1888 +/- 73 101 +/- 8 5.6 +/- 0.6 280 +/- 10 MV700039 4858 +/- 228 70 +/- 8 3.6 +/- 0.5 778 +/- 27 MV700040 7617 +/- 301 58 +/- 9 3 +/- 0.3 495 +/- 20 MV700041 24 917 +/- 762 117 +/- 14 14.9 +/- 0.9 2242 +/- 62 2007-8 GEO-1611 37 +/- 3 9 +/- 2 0.8 +/- 0.4 135 14

The standards are inserted sequentially into the sample stream at an overall proportion of 1 in 20 (i.e. 1 in 80 for each individual standard). The grades of these samples remain “blind” to the analytical laboratory. The primary (ALS Chemex) and secondary (ACT) laboratories are not involved in the preparation of the standards (SGS Laboratory).

12.3.4 Other QAQC samples

 Pulp duplicates are second splits of the pulps. These samples are routinely analysed by the laboratory. While these samples are good indicators of the assay reproducibility (precision) they are not blind for the laboratory, and their value is therefore diminished. These are inserted at a proportion of 1 in 20.

 Pulp blanks (internal laboratory samples), are samples of pulverised barren material. These samples provide a check on contamination during assaying. The pulp blanks are inserted immediately after highly mineralised samples. These are inserted at a proportion of 1 in 20.

 Check samples (same pulp, externally analysed) are second splits of pulps resubmitted to an external certified laboratory under a different sample number. These samples are used to estimate the assay accuracy, together with the standards. These are submitted at a proportion of 1 in 20.  Coarse duplicates (or preparation duplicates) are splits of some samples taken after the first

crushing and splitting step; these samples provide information about the sub-sampling variance. These are inserted at a proportion of 1 in 20.

12.3.5 Referee laboratory

ACME has been selected as the referee laboratory for the Constancia drilling program. Pulps and coarse rejects have been sent for check analysis. Standards and blanks are inserted in these check batches as in a standard batch.

12.4 STATEMENT ON SAMPLE PREPARATION AND ANALYSIS

GRD Minproc is of the opinion that Norsemont’s site-based sample preparation procedures are of industry standard. Similarly, the chain of custody and security procedures is considered to conform to industry best practice.

GRD Minproc is of the opinion that the Norsemont QAQC sampling protocol is rigorously set up and is continuously monitored to identify potential sampling and assaying problems.