Pilot Tests at Tiris Uranium Project

Aura's database was managed by the independent organisation Reflex Hub, based in Perth.

H&SC conducted data validation checks such as comparing assay certificates to database records and a variety of checks for internal inconsistencies such as overlapping intervals, records beyond end of hole depth, unassayed intervals and unrealistic drill hole data.

H&SC has not visited the Tiris East deposits due to time and budget constraints. H&SC based its view of the geological setting and mineralisation on drill hole data, discussions with Aura geologists and on information in technical reports. Representatives of Coffey Mining and Wardell Armstrong International conducted site visits in Aril 2012 and May 2016 respectively.

The uranium mineralisation generally forms shallow horizontal tabular bodies ranging in thickness from 1 to 12 m hosted in weathered granite and granitic sediments. Differentiation of the weathered granite from granitic sediments is unreliable from AC sample returns. A purely geological model of the Tiris deposits has not been produced.

H&SC created a surface representing the base of the estimates in order to limit the extrapolation of grades into volumes that had no data. This is important at Tiris East as there is a general decrease in uranium grades with depth. This surface nominally represents the top of the less-weathered granite, where AC drilling could penetrate no further. The base surface was produced using the locations of the end of the deepest assay from each drill hole. Where drill holes were very close, within around 15 m, the shallower point was removed. The base surface also honoured mapped surface outcrops.

At the time that the estimates were completed, no topographic survey data were available. The vast majority of the 2017 drill collar locations were surveyed using a Differential Global Positioning System (DGPS). H&SC used the locations of all drill hole collars that had been located with the DGPS to create a wireframe representing the topographic surface. The elevations of all drill holes that had been located using a handheld GPS were then derived from this topographic surface.

The proportion of the block between the topographic and base surfaces were assigned to the block model and used to weight the reported estimates.

The interpretation of the mineralisation as flat lying tabular bodies is undisputed. The lateral extents of the mineralisation are poorly defined and additional drilling around the edges of the deposits may indicate that mineralisation is more limited than currently interpreted. Alternative interpretations of the geology are very unlikely to significantly impact estimated resources.

The continuity of both grade and geology are affected by the extent of weathering of the granitic host. The continuity does not appear to be affected by faulting.

The Mineral Resources reported here occur in four separate areas (Hippolyte North, Hippolyte South, Lazare North and Lazare South) within a SE trending rectangle around 40 km north-south and 12 km east-west. All mineralisation forms flat lying tabular bodies ranging in thickness from 1 to 12 m.

The Mineral Resources at Hippolyte North at a cut-off of 100 ppm U3O8 occur in an area 6 km east-west and 5.5 km north-south. This region is comprised of several separate areas that range in plan dimensions from 500 m to 1.1 km wide and 500 m to 2.2 km long. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 11 m below surface.

The Mineral Resources at Hippolyte South at a cut-off of 100 ppm U3O8 occur in an area 5.6 km east-west and 5.4 km north-south. This region is comprised of three isolated areas each with a north-south length of around 1.3 km and an east-west length that ranges 400 m to 1.1 km. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of six metres below surface

The Mineral Resources at Lazare North at a cut-off of 100 ppm U3O8 occur in an area 4.5 km east-west and 2.4 km north-south. This region is comprised of three isolated areas. The smallest of these areas has an east-west length of 900 m and a north-south length of 550 m. The largest area has an east-west length of 2.2 km m and a north-south length of 1.8 km.   The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 12 m below surface.

The Mineral Resources at Lazare South at a cut-off of 100 ppm U3O8 occur in an irregular shape with an east-west length of 5.5 km and a north-south length of 2.7 km. The largest area has an east-west length of 2.2 km m and a north-south length of 1.8 km.   The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 10 m below surface.

The uranium concentrations were estimated by recoverable Multiple Indicator Kriging (MIK) using the GS3 geostatistical software. The uranium grades at the Tiris East deposits exhibit a positively skewed distribution and therefore show reasonable sensitivity to a small number of high grades. MIK is considered an appropriate estimation method for the uranium grade distribution at the Tiris East deposits because it specifically accounts for the changing spatial continuity at different grades through a set of indicator variograms at a range of grade thresholds. It also reduces the need to use the practice of top cutting.

All drill hole intervals were composited to 0.5 m for estimation. The following number of half metre composites were used to estimate the deposits:

·      Hippolyte North: 9,920

·      Hippolyte South: 1,078

·      Lazare North: 1,585

·      Lazare South: 6,743

Top-cut values were chosen by assessing the high end distribution of the grade population within each zone and selecting the value at which the distribution became erratic. Only one composite in Lazar North was top-cut. This interval had a U₃O₈ grade of 7,937 ppm and was cut to 3,200 ppm.

The four deposits were subdivided into a total of seventeen Subzones for estimation. Conditional statistics were produced for each of the Subzones. All class grades used for estimation of the mineralised domains were derived from the class mean grades.

Vanadium is a potential by-product and vanadium oxide (V₂O₅) has been estimated for the mineral resources using the stoichiometric V₂O₅/U₃O₈ ratio for carnotite group minerals. These V₂O₅ values represent potentially recoverable vanadium in carnotite and not total vanadium occurring in mineralisation, which is significantly higher in almost all cases. These potentially recoverable V₂O₅ values are based on the analysis of a substantial database of available sample data and represent average values that may be conservative. This procedure relies on the correlation between uranium and vanadium in carnotite group minerals, which are the only uranium minerals identified to date at Tiris.

No deleterious elements or other non-grade variables of economic significance have been identified or estimated.

The base surface created to represent the top of the less-weathered granite was used to limit the extrapolation of grades into volumes that had no data.

The Recoverable MIK technique employed by H&SC in this case requires a set of 14 variogram models, one for each of the fourteen grade bins used. A set of variogram models were created for Subzones of the Hippolyte North, Lazare North and Lazare South deposits. These variogram models were applied to Subzones that did not have sufficient data to generate reliable models.

The Hippolyte North, Lazar North and Lazar South deposits have areas that have been drilled on a 50x50 m grid whereas the Hippolyte South areas have been drilled on a 100x100 m grid. Separate block models were created for Hippolyte North, Lazar North, Lazar South and for each of the three Zones in Hippolyte South. Nominal downhole sampling interval is 0.5 m. Drill hole grade data were composited to 0.5 m intervals. The block dimensions were 50 x 50 m in plan view and 1 m vertically. The plan dimensions were chosen as it is the nominal drill hole spacing (preferable for MIK estimation). The vertical dimension was chosen to reflect the anisotropy of the mineralisation and the downhole data spacing.

The minimum selective mining unit size is assumed to be 10x10x0.5 m.

A three pass search strategy was used to estimate the U₃O₈ grades at each of the deposits. Each pass required a minimum number of samples with data from a minimum number of octants of the search ellipse to be populated. Discretisation was set to 10x10x0.5 m. The search criteria are shown below. The short first axis of the search ellipse is vertical.

1.     1.5x60x60m search, 16-48 samples, minimum 4 octants

2.     1.5x150x150m search, 16-48 samples, minimum 4 octants

3.     2.4x240x240m search, 16-48 samples, minimum 4 octants

The maximum distance of extrapolation of the reported estimates from drill hole data points is limited to 220 m.

The Hippolyte North and Lazar North deposits were estimated by Mr. Mapeto of Coffey Mining in 2011. Lazar South was estimated by Mr. Mapeto in 2012. H&SC has access to these block models and considers that the current Mineral Resource Estimate takes appropriate account of these models. Significant additional drilling has occurred since these estimates were produced so the volume and confidence category have increased. Reasonably large differences exist between the current and previous estimates due to differences in estimation methodologies.

No check estimates were produced.

No mining has occurred on the Tiris East deposits so mine production data were unavailable for comparison.

The final H&SC block model was reviewed visually by H&SC and Aura and it was concluded that the block model fairly represents the grades observed in the drill holes. H&SC also validated the block model statistically using histograms, boxplots, scatter plots and summary statistics.

Tonnages are estimated on a dry weight basis. The moisture content was not determined.

A cut-off of 100 ppm U₃O₈ cut off is used to report the resources as it is assumed that ore can be economically mined at this grade in an open pit scenario. This cut-off is considered to be relatively low compared to operating uranium mines, but metallurgical test work indicates that a significant upgrade in uranium and decrease in sulphates can be achieved by a simple grinding and sieving process.

All of the resources reported here have been estimated on the assumption that the deposits will be mined by open-pit.

Recoverable MIK allows for block support correction to account for the change from sample size support to the size of a mining block. This process requires an assumed grade control drill spacing and the assumed size of the Selective Mining Unit (SMU). The variance adjustment factors were estimated from the U₃O₈ metal variogram models assuming a minimum SMU of 10x10x0.5 metres (east, north, vertical) with high quality grade control sampling on a 10x10x0.5 metre pattern (east, north, vertical).

The application of the variance adjustments to the resource estimates is expected to provide estimates of recoverable resources without the need to apply additional mining dilution or mining recovery factors. Internal dilution, that is, within the SMU unit is accounted for. If a larger SMU size or a broader grade control drill pattern is implemented the selectivity assumed in the reported resources may not be realised.

The metallurgical test work information supplied to H&SC indicates that the Tiris East deposits are amenable to a process of crushing, screening and an alkaline carbonate leach in order to recover uranium. Bench scale test work indicates that a significant upgrade in uranium and decrease in sulphate concentrations can be achieved through screening.

No penalty elements identified in work so far.

Metallurgical test work on Tiris ore has shown that about 55% to 58% of vanadium was also extracted during the alkaline leach. The V₂O₅/U₃O₈ ratios for the final leach liquor are close to the carnotite V₂O₅/U₃O₈ ratio, indicating that effectively only vanadium from carnotite is being leached under these conditions. To date, no vanadium extraction test work has been carried out for the recovery of vanadium from the pregnant leach solution, so further work is required to demonstrate that a marketable vanadium product can be produced on a commercial basis.

No further assumptions have been made.

Aura has informed H&SC that an Environmental and Social Impact Assessment has been completed which concluded there are no known issues arising from native title, historical sites, environmental or third party matters that are likely to materially affect exploitation. H&SC therefore assumes that there are no known unusual aspects of the Tiris East deposits that may lead to adverse environmental impacts beyond what is expected from a mining operation.

Waste rock and process residue are expected to be disposed of in the areas surrounding the deposits and processing facility, in a responsible manner and in compliance with local mining law.

Dry bulk density of diamond drill core was measured at the ALS facility in Nouakchott using an immersion method (Archimedes principle) on selected PQ diamond drill core intervals ranging in size from 10 to 30 cm. Competent pieces of drill core were selected on a nominal interval of 50 cm. The samples chosen are believed to be representative of the surrounding rock type. All density samples are wrapped in cling film to avoid water absorption. A total of 304 density measurements have been taken from drill core at the Tiris East deposits with values ranging from 1.55 to 2.66 t/m3.

Measured density values show that there is a reasonable correlation between density and the depth of the sample. A regression was used to assign densities to each block in the block model based on the depth below surface.

The classification is based on the search pass used to estimate the block. In order to limit small, isolated volumes of different classification (spotted dog effect) the search passes used to populate each block were locally averaged. Pass one nominally equates to Measured Resources, Pass two translates to Indicated Resources and Pass three equates to Inferred Resources.

This scheme is considered by H&SC to take appropriate account of all relevant factors, including the relative confidence in tonnage and grade estimates, confidence in the continuity of geology and metal values, and the quality, quantity and distribution of the data.

The classification appropriately reflects the Competent Person's (Arnold van der Heyden) view of the deposit.

This Mineral Resource estimate has been reviewed by Aura personnel. The estimation procedure has also been internally reviewed by H&SC. No material issues were identified as a result of these reviews.

No external audits have been completed on the Mineral Resource estimates.

The relative accuracy and confidence level in the Mineral Resource estimates are considered to be in line with the generally accepted accuracy and confidence of the nominated JORC Mineral Resource categories. This has been determined on a qualitative, rather than quantitative, basis. The main factor that affects the relative accuracy and confidence of the Mineral Resource estimate is sample data density due to the reasonably high variability in uranium grades.

The estimates are global although the resources classified as Measured and Indicated are suitable for long term mine planning studies. It should be noted that the Indicated Resources are based on broadly spaced data and may be locally inaccurate. Closer spaced drilling is necessary prior to detailed mine planning.

No production data are available as only small scale illegal artisanal mining has occurred around the Tiris East deposits.