お知らせ • Mar 04
Ionic Rare Earths Limited Announces Mineral Resource Estimate Increased Threefold at Makuutu
The Board of Ionic Rare Earths Limited advised of a substantial 210% increase to the Mineral Resource Estimate ("MRE") at its 51% owned Makuutu Rare Earths Project ("Makuutu"), which is estimated at 315 Million tonnes at 650 ppm Total Rare Earth Oxide ("TREO") with a cut-off grade of 200 parts per million ("ppm") TREO minus CeO2. This updated MRE places Makuutu amongst the adsorption clay ("IAC") deposits, and as such, a globally strategic resource for low-cost, high-margin and long-term security of critical and heavy rare earth ("HREO") supply. The Makuutu MRE has been updated based on the following key inputs: 279 drill holes for 4,754 metres of drilled between October 2019 and October 2020; Includes 54 infill drill holes completed on a 200 metre grid on the Makuutu Central area increasing resource confidence to Indicated status in that area; Includes 8 infill drill holes on a 100 metre grid on the Makuutu Central area evaluating short range variability in head grade and extraction; 487 insitu dry bulk density measurements from drill core samples; and marginal cut-off grade parameters based on Makuutu Rare Earth Element ("REE") extraction metallurgical test results, project-based cost estimates and REO product pricing reflecting current and forecast REO prices. The MRE was conducted over eleven (11) low plateaus defined by radiometric eU/eTh anomalism on mineral licences RL00007, RL1693 and EL1766. 11 areas from A to I where drilling and resource estimation was focused along with the Makuutu Central Zone ("MCZ"). The highly prospective EL000147 was not included in this MRE as the exploration license was only acquired in January 2021. The MRE only includes clay and saprolite regolith types with surface hardcap material excluded while processing alternatives are tested for this material. This is consistent with the Company's knowledge of other IAC deposits, especially the southern Chinese deposits. The initial metallurgical response highlighted by results of testing the clay and saprolite samples appears consistent with other global IAC deposits, including the southern Chinese deposits which are responsible for the global production of more than 95% of the HREO production. The MRE has determined classified resources in nine (9) of the eleven (11) drilled areas. Indicated Resources are constrained to the Central Zone where the 200 metre x 200 metre drill spacing has provided adequate data for this level of confidence. The Inferred Resource areas are drilled on a 400 metre x 400 metre spacing and will require further infill drilling to increase resource confidence. Areas C and E have failed to convert to resources at this time, with mineralisation lacking sufficient continuity at the 400 metre x 400 metre drill spacing to be classified. These areas can be tested with closer spaced drilling in the future to provide more confidence in the continuity of mineralisation, which will have the potential to add further resource. The disruption to the continuity in these areas is primarily due to unmineralised sand units, intercalated with mineralised clays, resulting in insufficient mineralised intersections to provide resource estimate confidence. As such, Exploration Targets have been maintained for these areas and future core drilling will look to convert these to additional resource. Sample lengths were determined by geological boundaries with a maximum sample length of 1 metre applied in clay zones and up to 2 metres in laterite zones where core recovery was occasionally low. Where the core contained continuous lengths of soft clay a carving knife was used to cut the core. When the core was too hard to knife cut it was cut using an electric core saw. Using either method, core was initial cut in half then one half was further cut in half to give quarter core. Quarter core was submitted to ALS for chemical analysis using industry standard sample preparation and analytical techniques. Half core was collected for metallurgical test work. Certified reference materials ("CRM"), analytical blanks, and field duplicates were used as part of the QAQC procedures and were each inserted at a rate of 1:25 samples. Alternate method analysis has been conducted on a selection of sample pulps using Laser Ablation MS technique at Bureau Veritas Minerals laboratory in Perth WA. All DDH samples were dispatched by air freight direct to ALS laboratory Perth, Australia. Sample preparation included whole sample crushing to 70% less than 2mm, Boyd rotary slitting to generate a 750g sub-sample, and pulverising to achieve better than 85% passing 75 microns. Analysis for REE suite was through Lithium Borate Fusion ICP-MS (ALS code ME-MS81), with elements analysed at ppm levels. This method is considered a total analysis. The geological interpretation utilised lithological logging data, and assay data to guide and control the Mineral Resource estimation. LeapfrogTM implicit modelling software was utilised to generate
three-dimensional wireframes of the applicable regolith units. Estimation domains were based on grouping of the regolith domains into five zones as defined by regolith rheology, and by comparison of regolith statistics: Domain 1, 2, 3 Cover zone (Soil, Hardcap and Transition regolith zones); Domain 4 Mottled zone (Mottled regolith zone); Domain 5 Clay zone (Clay regolith zone); Domain 6, 7 Saprolite zone (Upper and Lower Saprolite regolith zones); and Domain 8, 9 Basement zone (Saprock and Fresh Rock regolith zones). Drill hole sample data was flagged using domain codes generated from three-dimensional mineralisation domains. Sample data was composited to one-metre downhole lengths using a best fit-method. No residuals were generated. Statistical analysis was carried out on data from all estimated domains, with hard boundary techniques employed within each estimation domain. Analysis of the composite data indicated the presence of outlier values indicating grade capping was required for Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sc, Sm, Tb, Th, Tm, U, Y and Yb. Capped values were generally selected above the 99th percentile. A total of 15 REE grade attributes (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), the associated element Sc, and 2 deleterious elements (U, and Th) were estimated. Final estimated values are converted to stoichiometric oxide values by calculation using published ratios to support reporting of rare earth oxides (REO). The grade estimation process was completed using Maptek Vulcan software using Ordinary Kriging (OK) together with dynamic anisotropy to guide the grade interpolation parallel to the regolith boundaries. For estimation domains with insufficient sample data a variogram model from a comparable domain was assigned. Interpolation parameters were derived using standard exploratory data analysis techniques of statistical and continuity analysis.
