Sampling techniques |
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 down hole 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. |
The 2018 Häggån resource estimate was based on several drilling campaigns: § 2008: 3453m in 17 diamond drillholes § 2010: 5091m in 25 " § 2011: 2279m in 10 " § 2012: 2226m in 14 " § 2015: 149m in 1 " § 2017: 374m in 2 " § 2018/19: 2929m in 22 " All drill samples were obtained by diamond drilling. Drillcore samples were provided to ALS Laboratories core sawing and for sample preparation and analysis. The Alum Shale, host to the mineralisation has a relatively consistent content of the target metals. Sample interval in most cases was 2m except where there was a lithological contact. Each lithology was sampled separately. Sample was dried at 105°C, then crushed to 70% -6 mm using ALS-Chemex method Prep22. 100 g was split using a riffle splitter by method SPL21, followed by fine pulverizing to 85% less than 75 micron by method PUL31. 10-20 grams of pulp subsample were dispatched to ALS in Ireland for ICP multi-element analysis. |
Drilling techniques |
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). |
Diamond drill core; standard tube; all but one hole were drilled vertically All holes were drilled with BQTQ (core diameter 47mm) All holes were surveyed downhole for direction at usually 3m intervals. The holes show minimal downhole deviation , with a maximum location error at the bottom of a hole of c. 6m. |
Drill sample recovery |
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. |
Any core loss is marked by the drillers and then recorded in the log by the geologist. The Alum Shale, host to the mineralisation, consistently has recoveries of +95%. In addition the material has relatively consistent values of the target metals. |
Logging |
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. |
Core was aligned and checked for continuity and marked out in one meter intervals. It was checked for drill bit marking as bit matrices are known to contain molybdenum. Comments were recorded in the database regarding the presence of bit marks. Core was geologically logged recording lithology, oxidation, mineralogy (where possible), texture & structure and scanned with a handheld scintillometer. Down hole depth intervals were recorded with an accuracy of 20 cm. All core was photographed. All core was geologically logged. |
Sub-sampling techniques and sample preparation |
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. |
Core was sawn in half using a core saw. All drill holes were diamond drill holes. · Half core was taken using a sample interval of 2 m. Sample was dried at 105°C, then crushed to 70% -2 mm using ALS method Prep22. 100 g was split using a riffle splitter, followed by fine pulverizing to 85% less than 75 micron by method PUL31. · 10-20 grams of pulp subsample were dispatched to ALS in Ireland for ICP analysis. · Precision of sampling and analysing pulps is considered to be within +/- 5% and acceptable for use in resource estimation at any confidence level. The grain size of the Alum Shale is extremely fine, less than 10 microns, and commonly around 1 micron. The uranium mineralisation is finely disseminated throughout the shale, again at a micron scale or less. Consequently the mineralisation and its host rock are very well represented in the 2m samples of core collected (average sample 3.3 kg). Because of the extremely fine nature of the mineralisation each drill core sample may contain many millions of individual grains of uranium minerals. Therefore sample size is appropriate. |
Quality of assay data and laboratory tests |
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. |
Because of the very fine nature of the host Alum Shale and the mineralisation minerals, it is considered that the laboratory procedures are appropriate for this mineralisation. The ICP method after 4 acid digestion is considered to give near total assay for all resource elements. ALS also assayed 2 standards, 1 duplicate and 1 blank for each batch of 40 samples as part of their internal QAQC. QAQC data were inspected by Aura before data were accepted and entered into the Aura database. In addition Aura inserted 1 blank, 1 certified reference sample and 1 duplicate in every 25 samples for QAQC Review of these QAQC results indicates acceptable levels of accuracy and precision have been established. |
Verification of sampling and assaying |
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. |
No twin holes were drilled. The following information primary data is recorded: Collar, alteration, assays, drilling type, Geology, Geotech, Magnetic susceptibility, mineralisation, radiometrics, samples, scintillometer, spectrometer, structure, veining, surface samples, batch details. All logging was done by the geologist digitally in an Excel spreadsheet. Photos of the core are taken after the hole was logged. Data is kept on site on an external hard drive as well as being sent by email to Aura Energy in Australia where it was uploaded into the independently managed EarthSQL data base. No data enters the database without verification by the Database Manager. Database managed by external contractor EarthSQL. In house copy and backup offsite. No adjustment to assay data. |
Location of data points |
Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation. Specification of the grid system used. Quality and adequacy of topographic control. |
Drill hole collar locations have been surveyed by with an accuracy of 20 cm. Initial location is taken during drilling with handheld GPS when the casing has been put down. All 2018/19 holes were recorded in grid system SWEREF 99 TM, the standard Swedish projection. Holes were vertical in all cases except Hole 39. The drilling contractor conducted down hole surveys for deviation using a Reflex Ex Trac survey device with a reading at 3m intervals. Downhole deviation was slight. The 2018/19 drillholes are located on an approximate 100 m by 100 m grid with 2 holes placed centrally within the the 100m squares; exact locations depended partially on access. Topography: RL was surveyed by DGPS with an accuracy of c. 20 cm. |
Data spacing and distribution |
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. |
All data reported in this release is based on drilling as described. The vast majority of sample intervals are 2 m in length, except where this interval contained a lithological contact, in which case each litholy was sampled separately. |
Orientation of data in relation to geological structure |
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. |
The mineralisation occurs in sub-horizontal sheets. It is considered that vertical drilling is the most appropriate drilling orientation for this mineralisation. |
Sample security |
The measures taken to ensure sample security. |
Drillcore was collected by Aura personnel from the drillsite and immediately taken and housed in Aura's local locked core shed. After logging the core was transported to ALS Laboratories facility by either Aura or ALS personnel for core sawing, sample preparation and assaying. |
Audits or reviews |
The results of any audits or reviews of sampling techniques and data. |
The site was visited during the drilling program by independent resource consultant Rupert Osborn of H&S Consultants who reviewed and reported favourably on procedures employed. |
