Maiden Resource Estimate for South Basin at Nevada Lithium-Boron Project
- Total Indicated and Inferred Resource of 393 million tonnes at 0.9% Lithium Carbonate, 2.9% Boric Acid and 1.7% Potassium Sulphate (1.2% Lithium Carbonate Equivalent (LCE) (0.6% LCE cut-off)
- High-grade zone: Indicated and Inferred Resource of 65 million tonnes at 1.0% Lithium Carbonate, 9.1% Boric Acid and 2.2% Potassium Sulphate (2.0% Lithium Carbonate Equivalent1) contained within the total Resource (1.8% LCE cut-off)
- 3.4 million tonnes of Lithium Carbonate contained within the Resource
- Large Resource with significant tonnage of high-grade material and potential for open pit mining
- Excellent potential to expand the Resource which remains open to the north, south and east
- Drilling to commence in late October targeting extensions to high-grade
- Metallurgical test work in progress with initial results expected in November
The total Indicated and Inferred Mineral Resource has been estimated by RungePincockMinarco Ltd (ASX:RUL) at 393 million tonnes at 0.9% Lithium Carbonate (Li2CO3), 2.9% Boric Acid (H3BO3) and 1.7% Potassium Sulphate (K2SO4) (1.2% Lithium Carbonate Equivalent1) using a 0.6% LCE cut-off. The Resource Estimate is being reported in compliance with the JORC Code 2012 Edition.
The Mineral Resource remains open to the north, south and east and has significant potential to expand with successful exploration. North Basin, where Global recently obtained results for twenty historic drill holes, is not included in the Resource Estimate.
Global's Managing Director, Bernard Rowe commented: "This is an excellent result for Global Geoscience and comes just four months after securing this exciting lithium project. The maiden Resource Estimate completed by RungePincockMinarco clearly demonstrates the significant scale of the Rhyolite Ridge lithium-boron deposit. We are continuing to rapidly advance the project with metallurgical test work in progress and drilling at both North Basin and South Basin scheduled to commence in late October."
Mineral Resource Statement and Parameters
RungePincockMinarco ("RPM") was engaged by Global to undertake a JORC-compliant Mineral Resource Estimate at South Basin, part of the Rhyolite Ridge Lithium-Boron project in Nevada, USA. The cut-off was selected based on an RPM cut-off calculator assuming an open pit mining method, a US$8,000/t Li2CO3 price, a 90% metallurgical recovery for Li2CO3 and costs derived from a high-level technical report supplied by independent processing consultants to Global. The Resource is shown by classification in Table 1 (low cut-off) and Table 2 (high cut-off). Table 2 is inclusive of Table 1 and not additional (to view tables, please refer to link below).
Summary of Resource Estimate Parameters and Reporting Criteria
In accordance with ASX Listing Rules and the JORC Code (2012 Edition), a summary of the material information used to estimate the Mineral Resource is detailed below (for further information please refer to Table 1 in Appendix 1, in the link below).
- The Rhyolite Ridge Mineral Resource area extends over a north-south strike length of 2,450m (from 4,184,000mN - 4,186,450mN), has a maximum width of 1,250m (424,150mE - 425,400mE) and includes the 420m vertical interval from 1,920mRL to 1,500mRL.
- The Rhyolite Ridge Project tenements (unpatented mining claims) are owned by Boundary Peak Minerals LLC. Global Geoscience has entered into an exclusive option to purchase agreement with the owner. The unpatented mining claims are located on US federal land administered by the Bureau of Land Management (BLM).
- A site visit was conducted by John Zeise of RPM, a representative of the Competent Person for Mineral Resources, during September 2016. The site visit included inspection of the geology, drill core and the topographic conditions present at the site as well as infrastructure. During the site visit, Mr Zeise had open discussions with Global Geoscience's personnel on technical aspects relating to the relevant issues and in particular the geological data.
Geology and Geological Interpretation
- Lithium, boron and potassium mineralisation is stratiform in nature and is hosted within Tertiary-age carbonate-rich clay sediments, deposited in a shallow lake environment in the Basin and Range terrain of Nevada, USA.
Drilling Techniques and Hole Spacing
- Drill holes used in the Mineral Resource estimate included 18 trenches, 15 RC holes and 20 diamond holes for a total of 7,720m within the defined mineralisation. The full database contained records for 67 drill holes for 10,134m of drilling and trenching.
- All drill hole collars have been surveyed to the UTM Zone 11 NAD27 grid system. Collar surveys were completed by a contract surveyor, utilising a GPS device.
- No down hole surveys were conducted for the trenches or RC holes, therefore nominal surveys were designated. Down hole survey methodology for the diamond drilling was not recorded, however readings were conducted on approximate 30m intervals down hole.
- Drill hole spacing varies from approximately 200m by 200m in the well-defined portions of the deposit to 400m by 400m over the remaining areas.
- Drill holes were logged for a combination of geological and geotechnical attributes. The core has been photographed and measured for RQD and core recovery.
Sampling and Sub-Sampling Techniques
- Drilling was conducted by American Lithium Minerals Inc., the previous owner of the tenements between 2010 and 2011. For RC drilling, a 5 inch hammer with crossover-sub was used with sampling conducted on 1.52m intervals and split using a rig mounted rotary splitter. For diamond core, HQ core size diameter with standard tube was used. Core recoveries of 97% were achieved at the project. The core was sampled as half core at 1.5m intervals using a standard electric core saw.
Sampling Analysis Method
- Samples were submitted to ALS Chemex Laboratory in Reno, Nevada for sample preparation and analysis. The entire sample was oven dried at 105DEG and crushed to -2 mm. A sub-sample of the crushed material was then pulverised to better than 85% passing -75µm using a LM5 pulveriser. The pulverised sample was split with multiple feed in a Jones riffle splitter until a 100-200g sub-sample was obtained for analysis.
- Analysis of the samples was conducted using aqua regia 2-acid and 4-acid digest for ICP-MS on a multi-element suite. This method is appropriate for understanding lithium clay deposits and is a total method.
- Standards for Li, B, Sr and As and blanks were routinely inserted into sample batches and acceptable levels of accuracy were reportedly obtained. Overall, QAQC results deemed all assay data suitable and fit for purpose in Mineral Resource estimation.
- Lithium carbonate equivalent (LCE) calculated using a lithium carbonate (Li2CO3) price of US$8,000/t, a boric acid (H3BO3) price of US$800/t and a potassium sulphate (K2SO4) price of US$600/t. Metallurgical recoveries of 90% are assumed for Li2CO3 and H3BO3 and 50% is assumed for K2SO4. No adjustment has been made for net smelter return as it remains uncertain at this time. Based on grades and contained Li2CO3, H3BO3 and K2SO4, it is assumed that all commodities have reasonable potential to be economically extractable. Prices, costs and recoveries were obtained from a high level technical report supplied by independent processing consultants to Global Geoscience. The formula used for lithium carbonate equivalent (LCE) is:
-- LCE%= li2co3_pct+[((h3bo3_pct*800*0.9)+(k2so4_pct*600*0.5))/(8,000*0.9)]
- The Mineral Resource has been reported at a 0.6% LCE cut-off. The cut-off was selected based on an RPM cut-off calculator assuming an open pit mining method, a US$8,000/t Li2CO3 price, a 90% metallurgical recovery for Li2CO3 and costs derived from a high level technical report supplied by independent processing consultants to Global Geoscience.
- Samples were composited to 1.525m based on an analysis of sample lengths inside the wireframes. After review of the project statistics, it was determined that high grade cuts for B within three mineralised domains was necessary. The cuts applied ranged between 2,500ppm and 17,500ppm B, resulting in 14 composites being cut.
- The block dimensions used in the model were 100m NS by 50m EW by 5m vertical with sub-cells of 6.25m by 6.25m by 1.25m. This was selected as the optimal block size as a result of kriging neighbourhood analysis (KNA).
- Ordinary kriging (OK) grade interpolation was used for the estimate, constrained by Mineral Resource outlines based on mineralisation envelopes prepared using a nominal 1,000ppm Li cut-off grade with a minimum down-hole length of 3m. For internal high grade B zones, a nominal 5,000ppm B cut-off grade was used. Up to three passes were used to estimate the blocks in the model and more than 99% of blocks were filled in the first two passes.
- A total of 137 bulk density measurements were taken on core samples collected from diamond holes drilled at the Project using the water immersion technique. Bulk densities ranging between 1.8t/m3 and 2.11t/m3 were assigned in the block model dependent on mineralisation and lithology.
- The Mineral Resource was classified as Indicated and Inferred Mineral Resource based on data quality, sample spacing, and lode continuity. The Indicated Mineral Resource was defined within areas of close spaced diamond and RC drilling of less than 200m by 200m, and where the continuity and predictability of the mineralised units was good. The Inferred Mineral Resource was assigned to areas where drill hole spacing was greater than 200m by 200m and less than 400m by 400m.
Mining and Metallurgical Methods and Parameters
- Based on the flat dips, thicknesses and depths of the mineralised bodies that have been modelled, as well as their estimated grades, the potential extraction method is considered to be open pit mining. However, no mining optimisation has been completed at this stage. Initial metallurgical test work has shown that the mineralisation is amenable to beneficiation, reverse flotation of acid consuming calcite and acid leaching of Li, B and K.
About Rhyolite Ridge Lithium-Boron Project
The Rhyolite Ridge lithium-boron project is located close to existing road and power infrastructure in southern Nevada. The project has potential as a strategic, long-life, low-cost source of lithium, boron and potassium. Two sedimentary basins (North and South) contain thick, shallow, flat-lying zones of lithium-boron-potassium mineralisation. The mineralisation is hosted within carbonate-rich, fine-grained sediments (marl) that were deposited in a shallow lake/basin environment. Previous exploration includes over 100 drill holes. Global Geoscience has the exclusive right to purchase 100% interest in the project from the owner, a private Nevada company.
 Refer to Note 5 of Resource statement on page 3.
 Cut-off grades based on industry-typical mining and processing costs
 Boric acid is a boron compound and contains 17.5% boron
To view tables and figures, please visit:
About Global Geoscience Limited
Global Geoscience Limited (ASX:GSC) is a Sydney-based mineral exploration company specialising in greenfield exploration and mineral discovery. The Company's main focus is for copper, gold and silver on its mostly 100%-owned projects in Nevada and Arizona in the United States, and Peru in South America.
RPMGlobal Holdings Ltd
Global Geoscience Limited