5 Feb 2016 07:49
5 February 2016
W Resources Plc
("W" or the "Company")
La Parrilla JORC Estimate - 16% Increase in Contained WO3
W Resources Plc (AIM:WRES), the tungsten, copper and gold mining, exploration and development company with assets in Spain and Portugal, announces a significant upgrade to its JORC compliant mineral resource estimate at its La Parrilla Project, located in Spain, following the completion of the new mineral resource estimate by Golder Associates.
Highlights
- The total resources estimate for La Parrilla has increased to 51 million tonnes ('mt') at 0.096% WO3 (tungsten trioxide) and 0.108% Sn (tin)
- A substantial increase of 16% contained WO3 and 7% increase in average WO3 grade
- A large increase of 29% contained Sn and a 19% increase in Sn grade
- Importantly, the quality of the resource definition has also increased significantly, with an indicated resource of 36mt which equates to 70% of the total resource estimate, up from zero in the previous 2013 estimate
- Large resource of 13mt at 0.101% WO3 at 0.04% cut-off in the Fast Track Mine ('FTM') area including at a 800 ppm cut-off 6mt at 0.146% WO3
- Maiden resource at La Parrilla West ('LPW') of 3mt at 0.158% WO3 at 0.08% cut-off (LPW has the potential to significantly increase with further extension drilling)
- High grade outcrops at the FTM and at LPW provide the potential for access to high grade low cost ore in the critical early development years of the project.
La Parrilla JORC Resource 2016 – Golder Associates | ||||
Overall Mineral Resources at 0.04% WO3 cut-off | ||||
2016 Estimate | Previous 2013 Estimate | Change | ||
Total Resource | Million Tonnes | 51 mt | 47 mt | + 4 mt |
At WO3 Grade | 0.096% | 0.090% | + 7% | |
Sn (ppm) | 108 | 91 | ||
Indicated Resource | Million Tonnes | 36 mt | zero | + 36 mt |
At WO3 Grade | 0.096% | zero | ||
Sn (ppm) | 115 | zero | ||
Inferred Resource | Million Tonnes | 15 mt | 47 | - 32 mt |
At WO3 Grade | 0.095% | 0.090% | + 6% | |
Sn (ppm) | 92 | 91 | ||
New FTM and LPW Higher Grade Resources at 0.04% WO3 cut-off | ||||
2016 Estimate | Previous 2013 Estimate | Change | ||
FTM Indicated Resource | Million Tonnes | 11 mt | zero | + 11 mt |
At WO3 Grade | 0.0996% | zero | ||
FTM Inferred Resource | Million Tonnes | 2 mt | zero | + 2 mt |
At WO3 Grade | 0.1099% | zero | ||
LPW Indicated Resource | Million Tonnes | 1 mt | zero | + 1 mt |
At WO3 Grade | 0.216% | zero | ||
LPW Inferred Resource | Million Tonnes | 4 mt | Zero | + 4 mt |
At WO3 Grade | 0.998% | zero | ||
Mine optimisation of the resource has commenced and mine development plans and schedules will be completed and reported in Q2 2016.
Commenting on the results Michael Masterman, Chairman of W Resources said: "This larger JORC Mineral Resource estimate is a very strong result for W Resources, with a substantial upgrade in the quality of the resource estimate to the indicated category, and increases in grade and tonnage across the entire resource. The strong results in the FTM area and the LPW area confirm that the deposit is open to the south, west and north and that the recently discovered high grade outcrops can be incorporated into mine feed schedules.
"Mine planning and engineering is advanced and we look forward to the upgraded development and production plan in Q2."
Enquiries:
W Resources Plc Michael Masterman T: +44 (0) 20 7193 7463 www.wresources.co.uk | Grant Thornton UK LLP Colin Aaronson / Jen Clarke / Harrison Clarke T: +44 (0) 20 7383 5100 |
SI Capital - Joint Broker Andy Thacker / Nick Emerson T: +44 (0) 1483 413500 www.sicapital.co.uk | Gable Communications Justine James T: +44 (0) 20 7193 7463 M: +44 (0) 7525 324431 |
Northland Capital Partners - Joint Broker John Howes / Abigail Wayne (Corporate Broking) T: +44 (0) 20 7382 1100 www.northlandcp.co.uk |
About La Parrilla
The La Parrilla project site is situated in the Extremadura region of southwest Spain, in the Provinces of Caceres-Badajoz, approximately 310 km southwest of Madrid. The site has exceptional infrastructure in place, which is accessed directly from the highway along a 3 km asphalt road and is serviced by electricity and water. The project comprises a tungsten mine and a tungsten tailings project. The mineral resource estimated by Golder in February 2016 at 0.04% WO3 cut-off grade is 51 million tonnes at 0.096% WO3 and 0.108 Sn, making it one of the largest tungsten deposits in the western world.
Technical information in this report has been prepared in accordance with the JORC Code and approved for inclusion by Mr Fernando de la Fuente, and Mr. Andrew Weeks.
Technical information in this report and on the W website has been prepared in accordance with the JORC Code and approved for inclusion by Mr Fernando de la Fuente, is a 'qualified person' in respect of the AIM Rules for Companies with over 41 years' experience in the Exploration and Mining Geology industry. Mr de la Fuente holds a B.Sc. in Geology and an MSc in Geology from the University of Granada in Spain. He is also a member of the Spanish College of Geologists (Number 49), the Spanish Society of Mineralogy, founder member of the Spanish Society of Geology, member of the Spanish Association of Applied Geology to Mineral Deposits, member of the Society for Mining, Metallurgy and Exploration, Inc., member of PDAC.
Mr Andrew Weeks is the Competent Person responsible for the geological interpretation (wireframe model), Mineral Resource estimation and classification of La Parrilla Tungsten Deposit. Mr Andrew Weeks is a full-time employee of Golder Associates Pty Ltd and a Fellow of the Australasian Institute of Mining and Metallurgy. Mr Weeks has sufficient relevant experience to the style of mineralisation and type of deposit under consideration and to the activity for which he is undertaking to qualify as a Competent Person as defined in the JORC Code, 2012 Edition.
The JORC Code Assessment Criteria
The JORC Code, 2012 Edition describes a number of criteria, which must be addressed in the Public Reporting of Mineral Resource estimates. These criteria provide a means of assessing whether or not parts of or the entire data inventory used in the estimate are adequate for that purpose. The Mineral Resource estimates stated in this document are based on the criteria set out in Table 1 of that Code (Table 3).
Table 3: JORC Code Table 1
JORC Code Assessment Criteria | Comment |
Section 1 Sampling Techniques and Data | |
Sampling Techniques | ¡ Two types of samples were used in La Parrilla's Mineral Resources Estimate, samples collected from reverse circulation (RC) holes and from diamond drill (DD) holes. ¡ Fifty-seven RC holes were drilled at La Parrilla; forty of them were drilled in 2015. For the 2015 drilling campaign, all RC samples were collected at 1 m interval, weighing on average at 35 kg with an average recovery of 89%. RC samples from previous drilling campaigns were mostly collected at 3 m interval with a range of 1 m to 6 m in length. Sample weights and recovery are not known for these samples. ¡ Eighty DD holes were drilled at La Parrilla; fifteen of them were drilled in 2015. For the 2015 drilling campaign, DD samples were collected at various length depending on the geology, ranging from 1.7 m to 5.6 m with the majority taken at 3 m length. DD samples from previous drilling campaigns were mostly collected at 2 m or 3 m interval with a range of 0.5 m to 113 m in length. ¡ Site observation indicates that the DD samples show highly variable recovery, especially in the top 25 to 50 m. Coarse-grained and friable scheelite mineralisation is occasionally washed out in DD core sample; hence the inclusion of DD samples may provide a conservative estimate of Mineral Resources. |
Nature and quality of sampling (e.g. cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as downhole gamma sondes, or handheld XRF instruments, etc.). These examples should not be taken as limiting the broad meaning of sampling.
Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used.
Aspects of the determination of mineralisation that are Material to the Public Report. In cases where 'industry standard' work has been done this would be relatively simple (e.g. 'reverse circulation drilling was used to obtain 1 m samples from which 3 kg was pulverised to produce a 30 g charge for fire assay'). In other cases more explanation may be required, such as where there is coarse gold that has inherent sampling problems. Unusual commodities or mineralisation types (e.g. submarine nodules) may warrant disclosure of detailed information. | |
Drilling Techniques | ¡ DD method uses NQ and HQ drill sizes. Core was not orientated. ¡ All La Parrilla RC drilling during 2015 used 140 mm diameter face-sampling bits with an effective sampling diameter of 136 mm. |
Drill type (e.g. core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc.), and details (e.g. core diameter, triple or standard tube, depth of diamond tails, face‑sampling bit or other type, whether core is oriented and if so, by what method, etc.). | |
| Drill Sample Recovery | |
¡ Sample recovery and sample weight are not available for RIOIBEX's drill holes drilled between 1985-1986. ¡ Sample recovery and sample weight were recorded onto a logging sheet, photographed and inserted in an Excel spreadsheet. ¡ DD holes drilled between 2007 to 2012 have an average recovery of 73%. DD holes drilled in 2015 have an average recovery of 92%. Site observation indicates that the DD samples show highly variable recovery, especially in the top 25 to 50 m. Coarse‑grained and friable scheelite mineralisation is occasionally washed out in DD core sample. ¡ RC holes drilled in 2015 have an average recovery of 89%. | |
Method of recording and assessing core and chip sample recoveries and results assessed.
Measures taken to maximise sample recovery and ensure representative nature of the samples.
Whether a relationship exists between sample recovery and grade and whether sample bias may have occurred due to preferential loss/gain of fine/coarse material. | |
| Logging | |
¡ All DD core logging captures degree of weathering, and angles, width and mineralogy of the quartz- scheelite veining. ¡ No logging data exists for the RIOIBEX RC drilling, but IRS RC campaigns in 2015 records the weight of the sample. A UV and sometimes lens reconnaissance is done but recorded in sheets and tables used for reference, not incorporated in the database. Measuring the width of veining over the RC sample interval is not possible. ¡ Field logging is recorded on paper and uploaded onto Microsoft Excel. All drill hole data is subsequently imported in to GEMCOM database. | |
Whether core and chip samples have been geologically and geotechnically logged to a level of detail to support appropriate Mineral Resource estimation, mining studies and metallurgical studies.
Whether logging is qualitative or quantitative in nature. Core (or costean, channel, etc.), photography.
The total length and percentage of the relevant intersections logged. | |
| Sub‑Sampling Techniques and Sample Preparation | |
¡ La Parrilla RC sampling in 2015 was by the following process: § Drill collar location is pegged in the field by proper surveying using total station. § Sighter lines are established alongside the planned collar location to allow correct alignment of the drill rig. § The sample "lot" is bagged at 1 m increments at the drill rig. Samples are placed over a thick rubber carpet to prevent damage. § Sample bags are loaded into a skip and transported to La Parrilla sample farm. § Each 1 m lot is dried, weighted and ground to a particle size of nominal 75% passing 1 mm, with an average 87% passing. Sample is then split to approximately 3 kg through a 3-tiered Jones riffle splitter. § Each one-meter 3 kg sample is despatched to ALS Chemex in Camas, Seville to prepare 200 gm pulps. ¡ DD cores drilled by IRS are cut by diamond saw along a line marked down the centre of the core, splitting the core into two equal halves. One half of the core and half of the fines is ground to a particle size of nominal 75% passing 1 mm, with an average 87% passing ¡ The remaining half core, together with half the fines collected at the diamond saw are stored in core tray on site. ¡ All pulps are flown to ALS Chemex laboratory in Ireland for assay. A 0.200 g sample is added to lithium metaborate flux (0.90 g), mixed well and fused in a furnace at 1000°C. The resulting melt is then cooled and dissolved in 100 mL of 4% HNO3 or 2% HCl3 solution. This solution is then analysed by Inductively Coupled Plasma - Mass Spectroscopy (ICP-MS). ¡ At ALS facilities, a 0.200 g sample is added to lithium metaborate flux (0.90 g), mixed well and fused in a furnace at 1000°C. The resulting melt is then cooled and dissolved in 100 mL of 4% HNO3 or 2% HCl3 solution. This solution is then analysed by ICP-MS. ¡ When W or Sn assays are above detection limit samples are flown to ALS in Vancouver for assay with XRF12k ¡ The following elements were included in the analysis: As (only for RC samples), Ba, Ce, Cr, Cs, Dy, Er, Eu, Ga, Gd, Hf, Ho, La, Lu, Nb, Nd, Pr, Rb, Sm, Sn, Sr, Ta, Tb, Th, Tm, U, V, W, Y, Yb and Zr. | |
If core, whether cut or sawn and whether quarter, half or all core taken.
If non‑core, whether riffled, tube sampled, rotary split, etc., and whether sampled wet or dry.
For all sample types, the nature, quality and appropriateness of the sample preparation technique.
Quality control procedures adopted for all sub‑sampling stages to maximise representivity of samples.
Measures taken to ensure that the sampling is representative of the in situ material collected, including for instance results for field duplicate/second-half sampling.
Whether sample sizes are appropriate to the grain size of the material being sampled. | |
| Quality of Assay Data and Laboratory Tests | |
¡ Short wave UV light was used to identify the presence of scheelite in the core but is not use as a quantitative or semi-quantitative method. ¡ The historic drilling campaigns had field duplicates representing 3% of submitted samples. Samples were submitted to Geomet Laboratory in the UK with those samples returning WO3 results greater than 400 ppm re-assayed at Adaro laboratory, Spain. The historic samples were originally assayed through pressed pellet XRF but this was changed to fused bead XRF after contamination issues were found. ¡ 116 repeats of pulps (2%) from historic drill holes were sent to an external laboratory with analyses done using fused bead XRF, pressed pellet XRF, ICP-MS and X-ray techniques. ¡ In the 2012 and 2015 drilling campaigns, internationally certified standards, blanks samples and duplicate samples were regularly introduced within each sample batch. ¡ Internal laboratory cross checking methods are implemented by ALS. ¡ Substantial duplicate samples were collected for the optimisation of sub-sampling procedures. ¡ Assay data reported as per laboratory final reports and certificates. | |
The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total.
For geophysical tools, spectrometers, handheld XRF instruments, etc., the parameters used in determining the analysis including instrument make and model, reading times, calibrations factors applied and their derivation, etc.
Nature of quality control procedures adopted (e.g. standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (i.e. lack of bias) and precision have been established. | |
| Verification of Sampling and Assaying | |
¡ Thirteen twin holes were drilled and result shows DD samples are losing coarse-grained, friable scheelite mineralisation due to drilling method. Study also shows that samples closer to the surface and inside the pit show higher variance due to the effect of weathering and blasting. ¡ All core boxes are photographed and a photo archive is maintained within the drilling database. | |
The verification of significant intersections by either independent or alternative company personnel.
The use of twinned holes.
Documentation of primary data, data entry procedures, data verification, data storage (physical and electronic) protocols.
Discuss any adjustment to assay data. | |
| Location of Data Points | |
¡ All drill holes drilled since 2007 have been surveyed by total station with drill hole collar coordinates referenced to the European Datum 50 grid and ETRS89 grids. Rioibex drill holes have accurate drill collar location surveyed by total station and photorestitution map. ¡ All drill holes have downhole survey information. Drill holes from the La Parrilla drill campaigns have been surveyed at mostly less than 50 m downhole interval. In 2015, DD holes downhole survey measurement are mostly taken at 12 m interval and No downhole survey were carried out for RC holes. ¡ Downhole survey are taken using Eastman single shot for the RIOIBEX drilling campaign, Eastman multishot for the Hercynian drilling campaign, Reflex Gyro for drill holes drilled during 2012 and DeviTool-PeeWee in 2015. ¡ New restitution topographic map with 1 m contours from 2015 flight and bathymetric sonar survey was used. | |
Accuracy and quality of surveys used to locate drill holes (collar and downhole surveys), trenches, mine workings and other locations used in Mineral Resource estimation.
Specification of the grid system used.
Quality and adequacy of topographic control. | |
| Data Spacing and Distribution | |
¡ Completed drill holes were designed for testing different targets and have irregular spacing. ¡ Data spacing is irregular but close to the existing pit, drill holes are spaced at approximately 25 m by 25 m. Samples are collected as 1 m downhole and no additional sample compositing has taken place. ¡ Data spacing and distribution is currently considered by the Competent Person to be sufficient only for Indicated and Inferred Mineral Resources and thus currently not sufficient to support an Ore Reserve estimate. | |
Data spacing for reporting of Exploration Results.
Whether the data spacing and distribution is sufficient to establish the degree of geological and grade continuity appropriate for the Mineral Resource and Ore Reserve estimation procedure(s) and classifications applied.
Whether sample compositing has been applied. | |
| Orientation of Data in Relation to Geological Structure | |
¡ Drill holes have generally been drilled on lines normal to the strike of mineralisation. Drill holes are either vertical or commonly -60° toward 300°. | |
Whether the orientation of sampling achieves unbiased sampling of possible structures and the extent to which this is known, considering the deposit type.
If the relationship between the drilling orientation and the orientation of key mineralised structures is considered to have introduced a sampling bias, this should be assessed and reported if material. | |
| Sample Security | |
¡ Security of historic RIOIBEX drill samples is unknown. ¡ La Parrilla drill samples are packaged on site and sent to ALS Chemex in Camas, Seville for preparation of pulps with a chain of custody system in place for samples drilled during the La Parrilla campaigns. Pulp samples are then flown to ALS Chemex in Ireland or Canada under ALS Chemex security and chain of custody procedures. ¡ Core samples were packed on thick plastic bags with sample reference indicated both in the outside and inside with permanent ink marker pens. For transport, the plastic bags were packed in thick plastic containers with sample reference indicated on the outside with permanent ink marker. ¡ All RC samples were packed in thick plastic bags with sample reference indicated both on the outside and inside with permanent ink marker pens. For transport, the plastic bags were packed in big-bags containers. ¡ Depending on the number of samples and urgency of the results, contract freight companies or own driver have been used to transport the sample to sample preparation laboratory. | |
The measures taken to ensure sample security. | |
| Audits and Reviews | |
¡ La Parrilla has instigated many of the reviews of sampling techniques. Golder has been provided with the results of various check sampling programmes and completed its own independent analysis of the data provided. ¡ Results of these are presented in the sampling QAQC section above. | |
The results of any audits or reviews of sampling techniques and data. | |
| Section 2 Reporting of Exploration Results | |
Mineral Tenement and Land Tenure Status | ¡ The La Parrilla property consists of three mineral concessions: Adelaida (No.7766), Victoria (No. 7768-A) and La Parrilla (No. 7768-B). These concessions cover 1000 hectares, are currently owned by Arypex S.L, a private company owned by the Bonilla family. ¡ Arypex's concessions are valid until 2068. ¡ IRS exercised an option to acquire 100% of the Project from Arypex in August 2015. ¡ In addition, the Project is subject to a net smelter royalty payable on production (1.5% from sales). |
Type, reference name/number, location and ownership including agreements or material issues with third parties such as joint ventures, partnerships, overriding royalties, native title interests, historical sites, wilderness or national park and environmental settings.
The security of the tenure held at the time of reporting along with any known impediments to obtaining a licence to operate in the area. | |
| Exploration Done by Other Parties | |
¡ Exploration has been conducted by RIOIBEX during 1985 and 1986 and by Hercynian Resources during 2007 and 2008. Prior exploration was conducted by Peñarroya España SA; however, this data has since been lost. | |
Acknowledgment and appraisal of exploration by other parties. | |
| Geology | |
¡ La Parrilla deposit is a north-east striking tungsten deposit with scheelite mineralisation hosted within quartz veins ranging from stringers to stock work in nature. Veining dips predominantly at 30° to the south-east. | |
Deposit type, geological setting and style of mineralisation. | |
| Drill hole information | |
¡ Not applicable. Exploration results have previously been reported. This Table relates to the reporting of the Mineral Resource estimates. | |
Data aggregation methods | ¡ For the resource estimate, samples return with below detection limit grades are replace with half the detection limit and samples with grades above upper detection limit is replace with the upper detection limit. ¡ No metal equivalents used or stated |
Relationship between mineralisation widths and intercept lengths | ¡ Drill intersections are not reported as true widths. |
Diagrams | ¡ Not applicable. Exploration results have previously been reported. This Table relates to the reporting of the Mineral Resource estimates. |
Balance reporting | ¡ Not applicable. Exploration results have previously been reported. This Table relates to the reporting of the Mineral Resource estimates. |
Other substantive exploration data | ¡ Not applicable. Exploration results have previously been reported. This Table relates to the reporting of the Mineral Resource estimates. |
Further work | ¡ Further work will include detailed interpretation of results and further drilling. |
Section 3 Estimation and Reporting of Mineral Resources | |
Database Integrity | ¡ All drilling data is contained in an Excel database and stored by IRS. Validation in the database is set to prevent the accidental duplication, alteration or deletion of records suitable for use during this resource estimate. |
Measures taken to ensure that data has not been corrupted by, for example, transcription or keying errors, between its initial collection and its use for Mineral Resource estimation purposes.
Data validation procedures used. | |
| Site Visits | |
¡ Mr Andrew Weeks, Principal Mining Geologist, and Mr Sergio Tenorio, Senior Geologist from Golder visited the La Parrilla project on 7 and 8 August 2015. The purpose of the visit was to hold discussions with project staff and gain familiarity with the deposit geology and scale, site land-use and topography, and observe some site practices. ¡ Only RC drilling and sample collection was taking place at the time, so Golder did not observe DDH drilling or sampling nor visited the sample preparation laboratory. ¡ Mr Weeks and Mr Tenorio made the following observations: § The exploration programme is well organised. Office, laboratory, and sample preparations areas are clean, tidy, and in good repair. Housekeeping appears to be a priority. § RC drilling is to good international standards, although some safety procedures could be improved (e.g. rod handling procedure; maintenance and use of whip checks on sample hoses). § Drill pad preparation and set out is excellent. There are good controls on drill rig (hole) alignment. § RC sample recovery appears exceptional. § Discussion about processes and viewing of DDH core cutting and sampling area suggests that DDH processes are good standard. § The use of plastic boxes for core samples to prevent spillage from sample bags is innovative. § Plans for validation of RC sampling as discussed with site personnel are supported by Golder. § Land-use and topography should not be a major impediment in developing the site, although placement of waste dumps may be limited to flat areas in the south-east of the existing pit. § There appears to be sufficient space for adding additional circuits to the process plant. | |
Comment on any site visits undertaken by the Competent Person and the outcome of those visits.
If no site visits have been undertaken indicate why this is the case. | |
| Geological Interpretation | |
¡ The resource estimation has been based on the geological interpretation supplied by W Resources with minor corrections by Golder to improve three-dimensional (3D) conformity. W Resources examined the mineralised intercepts in each drill hole and grouped these into specific vein packages. ¡ W Resources provided Golder with the sectional interpretation of these vein packages, then Golder tied these together in 3D to create wireframe solids of each vein package. ¡ Three dimensional wireframe modelling were carried out using Vulcan® software. | |
Confidence in (or conversely, the uncertainty of) the geological interpretation of the mineral deposit.
Nature of the data used and of any assumptions made.
The effect, if any, of alternative interpretations on Mineral Resource estimation. The use of geology in guiding and controlling Mineral Resource estimation.
The factors affecting continuity both of grade and geology. | |
| Dimensions | |
¡ The mineralised zone is approximately 1000 m long (north-west - south-east) by 400 m wide. The mineralisation goes from surface outcrop to approximately 300 m below the surface in the deepest zone. | |
The extent and variability of the Mineral Resource expressed as length (along strike or otherwise), plan width, and depth below surface to the upper and lower limits of the Mineral Resource. | |
| Estimation and Modelling Techniques | |
¡ Mineralisation was defined by mineralisation zones identified from downhole veining and geochemical data. Mineralised material is identified as being >1% accumulative vein across the sampling interval, other material is characterised as waste. ¡ The estimation technique used for the Mineral Resource estimation is the geostatistical method of Ordinary Kriging. Parameters were derived from variograms to estimate the average grade for WO3, Sn and As. ¡ Block sizes were selected with respect to the nominal drilling spacing to ensure acceptable local estimation quality. ¡ The block size selected for this deposit is 10 m (X) by 10 m (Y) by 5 m (Z). The sub-block size is 5 m (X) by 1 m (Y) by 2.5 m (Z). ¡ All samples were composited to 3 m for estimation purposes. ¡ The estimation was conducted in three passes with the search size increasing for each pass. ¡ High grade spatial restraining was applied for grade estimation of individual domains. The threshold uses to restrict high grades was based on the assessment of sample statistics and probability plots. Restraining of high grades was to within 20 m by 20 m by 4 m distance inside the vein packages. ¡ Each individual domain was estimate separately and an unfolding technique was applied for estimation to better capture mineralisation continuity within the domains ¡ The model was validated visually and statistically using comparisons to composite data statistics, swath plots and evaluation of the grade estimation smoothing effect. | |
The nature and appropriateness of the estimation technique(s) applied and key assumptions, including treatment of extreme grade values, domaining, interpolation parameters, and maximum distance of extrapolation from data points. If a computer assisted estimation method was chosen include a description of computer software and parameters used.
The availability of check estimates, previous estimates and/or mine production records and whether the Mineral Resource estimate takes appropriate account of such data.
The assumptions made regarding recovery of by‑products.
Estimation of deleterious elements or other non‑grade variables of economic significance (e.g. sulfur for acid mine drainage characterisation).
In the case of block model interpolation, the block size in relation to the average sample spacing and the search employed.
Any assumptions behind modelling of selective mining units.
Any assumptions about correlation between variables.
Description of how the geological interpretation was used to control the resource estimates.
Discussion of basis for using or not using grade cutting or capping.
The process of validation, the checking process used, the comparison of model data to drill hole data, and use of reconciliation data if available. | |
| Moisture | |
¡ All tonnages are based on volume measurements converted using dry bulk densities. | |
Whether the tonnages are estimated on a dry basis or with natural moisture, and the method of determination of the moisture content. | |
| Cut-off Parameters | |
¡ The resource model is constrained by assumptions about economic cut-off grades. The tabulated resources were reported using cut-off grade of 400 ppm WO3 which was applied on a block by block basis. | |
The basis of the adopted cut-off grade(s) or quality parameters applied. | |
| Mining Factors or Assumptions | |
¡ W Resources have a vision to develop an open pit mining and processing operation at La Parrilla with production rates circa. 2.2 million per annum. ¡ Golder would expect that open pit production at those rates will require medium scale mining equipment - say 100 to 150 tonne excavators and matching truck fleet - on typical mining bench heights of around 2.5 to 5 m. ¡ Golder does not expect any visual control on ore-waste contacts during mining, especially during night shift, so future grade control practices will be critical for minimising misdirection. | |
Assumptions made regarding possible mining methods, minimum mining dimensions and internal (or, if applicable, external) mining dilution.
It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider potential mining methods, but the assumptions made regarding mining methods and parameters when estimating Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of the mining assumptions made. | |
| Metallurgical Factors or Assumptions | |
¡ Detailed test work on ore sorting, pressure jig, standard hutch jig, scrubbing tests, gravity concentration on the fines, plus arsenic flotation and electrostatic separation testing have been carried out. A preliminary 72.8% tungsten metal recovery is used in the modelling, however further optimization is needed in the backend gravity circuit to gain confidence in the process flowsheet. ¡ Arsenic removal is not an issue and investigation is underway for oxidizing the flotation product (sulfur flotation) for sale as a possible tertiary product. ¡ Arsenic content in the tungsten product can be reduced to below the EU transportable limit and subsequently end up with a clean, possibly saleable product. Alternatively, the arsenic can be oxidized to a stable form with bacteria before disposal. | |
The basis for assumptions or predictions regarding metallurgical amenability. It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider potential metallurgical methods, but the assumptions regarding metallurgical treatment processes and parameters made when reporting Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of the metallurgical assumptions made. | |
| Environmental Factors or Assumptions | |
¡ Golder is not aware of any environmental issues that would affect the eventual economic extraction of the deposit. ¡ While infrastructure requires some remediation prior to commencing operations, the site already has facilities for capturing process water, tailings residue facilities, and channels for diverting storm and flood water around the open pit. | |
Assumptions made regarding possible waste and process residue disposal options. It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider the potential environmental impacts of the mining and processing operation. While at this stage the determination of potential environmental impacts, particularly for a greenfields project, may not always be well advanced, the status of early consideration of these potential environmental impacts should be reported. Where these aspects have not been considered this should be reported with an explanation of the environmental assumptions made. | |
| Bulk Density | |
¡ Bulk density values were assigned based on mineralisation. The bulk densities were based on immersion measurements from 692 samples from 43 diamond drill holes. | |
Whether assumed or determined. If assumed, the basis for the assumptions. If determined, the method used, whether wet or dry, the frequency of the measurements, the nature, size and representativeness of the samples.
The bulk density for bulk material must have been measured by methods that adequately account for void spaces (vugs, porosity, etc.), moisture and differences between rock and alteration zones within the deposit. Discuss assumptions for bulk density estimates used in the evaluation process of the different materials. | |
| Classification | |
¡ Mineral Resources are classified according to the following criteria and assumptions: § Measured Resources: no measured material has been defined for this deposit. § Indicated Resources: - Has a relative drill spacing of 100 by 25 m or less - Has a higher estimation confidence as reflected by: · Blocks that have a kriging slope of regression above 0.7 · Blocks that are estimated within the first two passes · Blocks that are estimated with 16 or more samples § Inferred Resources: all remaining estimated blocks, generally represented by discontinuous and geologically complex zones with poor drilling coverage. ¡ Extrapolation of mineralisation from drill holes was limited to half of the nominal drill hole spacing on section. | |
The basis for the classification of the Mineral Resources into varying confidence categories.
Whether appropriate account has been taken of all relevant factors, i.e. relative confidence in tonnage/grade estimations, reliability of input data, confidence in continuity of geology and metal values, quality, quantity and distribution of the data. Whether the result appropriately reflects the Competent Person(s)' view of the deposit. | |
| Audits or Reviews | |
¡ This Mineral Resource estimate is an update to the previous estimates completed by Golder in 2013. ¡ No audits or reviews have been undertaken on this Mineral Resource estimate. | |
The results of any audits or reviews of Mineral Resource estimates. | |
| Discussion of Relative Accuracy/Confidence | |
¡ The La Parrilla Mineral Resource is an estimate of the global remaining in-situ WO3 after making allowances for historical mining. No reliable historical production data is available to compare with this resource estimate. ¡ The revised Mineral Resource estimate represents a 30% or a 5 million tonnes increase over the previous estimate. The increase in the total resource and higher resource confidence is attributable to improved definition to mineralised zones and extensions to mineralisation as a result of the completion of infill and extension on DD and RC drilling. ¡ The relative accuracy is reflected in the Mineral Resource classification discussed above that is in line with industry acceptable standards | |
Where appropriate a statement of the relative accuracy and confidence level in the Mineral Resource estimate using an approach or procedure deemed appropriate by the Competent Person. For example, the application of statistical or geostatistical procedures to quantify the relative accuracy of the resource within stated confidence limits, or, if such an approach is not deemed appropriate, a qualitative discussion of the factors that could affect the relative accuracy and confidence of the estimate.
The statement should specify whether it relates to global or local estimates, and, if local, state the relevant tonnages, which should be relevant to technical and economic evaluation. Documentation should include assumptions made and the procedures used.
These statements of relative accuracy and confidence of the estimate should be compared with production data, where available. | |