9 April 2019
Savannah Resources Plc
Mineral Resource Increase of 17% to 23.5Mt at Mina do Barroso Lithium Project
Significant scope for further expansions
Highlights
· Continued resource expansion at Mina do Barroso, increasing the Project's lead as Western Europe's most significant spodumene lithium Mineral Resource
· ~17% increase in overall JORC compliant Mineral Resource Estimate for the Project, which now stands at 23.5Mt at 1.02% Li₂O for 241,000t of contained Li₂O
· 100% of mineralisation within the Grandao Stage 1 pit classified as Measured or Indicated Mineral Resource
· 28% increase in Measured and Indicated Resource to 13.3Mt at 1.0% Li₂O representing 58% of the total Mineral Resource
· Inferred Mineral Resource established at Pinheiro of 2.0Mt at 1.0% Li₂O
· Exploration Target* remains unchanged for Mina do Barroso, calculated at 9-15Mt at 1.0-1.2% Li₂O, giving a potential mineral inventory of over 30Mt for the Project
· Recent test work has reduced iron content of the Mineral Resource by 41% to 0.8% Fe₂O₃ confirming a low iron deposit
· The Board believes significant upside remains at all deposits to further increase the resource inventory in addition to any potential inaugural Mineral Resource Estimate for the Aldeia Quarry Prospect
*Cautionary Statement: The potential quantity and grade of the Exploration Targets is conceptual in nature, there has been insufficient exploration work to estimate a mineral resource and it is uncertain if further exploration will result in defining a mineral resource.
Savannah Resources plc (AIM: SAV, FWB: AFM and SWB: SAV) ('Savannah' or 'the Company'), the resource development company, is pleased to announce a significant increase in the JORC 2012 Compliant Measured, Indicated and Inferred Mineral Resource Estimate, with supporting Exploration Target at the Company's flagship asset, the Mina do Barroso Lithium Project ('Mina do Barroso' or the 'Project'), located in northern Portugal (Figure 1 and Table 1-2). To view the press release with the illustrative maps and diagrams please use the following link: http://www.rns-pdf.londonstockexchange.com/rns/5067V_1-2019-4-8.pdf
Savannah's CEO, David Archer said: "This is the fourth major increase in the Mina do Barroso Mineral Resource and it has been achieved in less than 14 months. The increasing Mineral Resource highlights the continued growth potential for the Project which is underscored by the Exploration Target remaining unchanged. With a potential mining inventory of over 30Mt, we have a long-life asset that can become a secure, long term supply source of lithium which is a strategic metal for the burgeoning battery and Electric Vehicle industries of Europe."
Figure 1. Mina do Barroso Project Summary Map showing key deposits and drilling completed to date
Mineral Resource Summary
Table 1. Updated Mineral Resource Estimation Summary
Deposit |
Resource Class |
Tonnes |
Li2O |
Fe2O3 |
Li2O |
Mt |
% |
% |
Tonnes |
All Deposits |
Measured |
6.6 |
1.1 |
0.7 |
71,600 |
Indicated |
6.8 |
1.0 |
0.8 |
65,400 |
Inferred |
10.2 |
1.0 |
0.9 |
103,900 |
Total |
23.5 |
1.02 |
0.8 |
241,000 |
(Note: Minor rounding discrepancies may occur)
Table 2. Exploration Target Summary
Deposit |
Tonnage Range (Mt) |
Li2O % |
Lower |
Upper |
|
Reservatorio |
5.0 |
7.0 |
1.0-1.2% |
Grandao |
4.0 |
8.0 |
1.0-1.2% |
Total Mina do Barroso Exploration Target |
9.0 |
15.0 |
1.0-1.2% |
(Note: Minor rounding discrepancies may occur)
*Cautionary Statement: The potential quantity and grade of the Exploration Targets is conceptual in nature, there has been insufficient exploration work to estimate a mineral resource and it is uncertain if further exploration will result in defining a mineral resource.
Importantly, this exploration target only includes Grandao and Reservatorio with further upside remaining from the many other high priority exploration targets within the Project area.
Improved Confidence in the Mining Inventory
Reverse Circulation ('RC') and diamond drilling incorporated into this Mineral Resource update has focused on both improving the Mineral Resource Estimate category of the existing Mining Inventory, as well as targeting areas in and close to the potential open pit mining areas, defined as part of the Scoping Study. This work has led to some excellent results, now with 100% of the Mining Inventory within the stage one Grandao pit defined in the June 2018 Scoping Study being converted to either Measured or Indicated category and approximately 80% of the total mining inventory for Grandao now in the Measured or Indicated category.
Approximately 80% of the mining inventory defined in the scoping study for the NOA open pit is now in an Indicated Mineral Resource category.
This is an important stepping stone for the Feasibility Study as all material needs to be either Measured or Indicated to be considered as part of an Ore Reserve Estimate, which will be generated from the Feasibility Study (Figure 2).
Figure 2. Grandao Resource Estimate coloured by Category showing Scoping Study Stage 1 Pit
Recent drilling has also defined significant near surface mineralisation at the Pinheiro deposit that has the potential to add low strip, high-grade material to the early stage of the mining inventory (Figure 3).
Figure 3. Pinheiro Pegmatite wireframes and drilling
Assessment of Iron Contamination
Detailed test work by Savannah demonstrated that a large proportion of the assayed iron is due to contamination from the abrasion of steel sample preparation equipment. This was demonstrated by taking field duplicates of 208 samples and submitting them for analysis using ceramic sample preparation equipment. The duplicates had a Fe content 41% less than the original samples and this was attributed to contamination. The amount of contamination increased with lithium content, so a regression formula was developed to factor the Fe grade based on the lithium grade. The iron content of the mineralisation in the updated Mineral Resource estimates uses the factored Fe values to better estimate the true iron content of the mineralisation.
Mineral Resource Estimate
The Mineral Resource Estimate for the Grandao, NOA and Pinheiro Lithium Deposit has been updated by Payne Geological Services Pty Ltd, an external and independent mining consultancy - http://www.paynegeo.com.au/paul-payne. The Deposits forms part of Savannah's Mina do Barroso Lithium Project, located in northern Portugal. The Mineral Resource Estimates have been classified as Measured, Indicated and Inferred Mineral Resource in accordance with the JORC Code, 2012 Edition and is summarised in Table 3 and Appendix 1.
Table 3. April 2019 Mineral Resource Summary (0.5% Li2O cut-off)
Deposit |
Resource Classification |
Tonnes |
Li2O |
Fe2O3 |
Li2O |
Mt |
% |
% |
Tonnes |
Grandao |
Measured |
6.6 |
1.1 |
0.7 |
71,600 |
Indicated |
6.4 |
1.0 |
0.8 |
65,300 |
Inferred |
4.8 |
1.0 |
0.7 |
48,900 |
Total |
17.7 |
1.04 |
0.7 |
181,800 |
Reservatorio |
Measured |
|
|
|
|
Indicated |
|
|
|
|
Inferred |
3.2 |
1.0 |
1.4 |
32,000 |
Total |
3.2 |
1.0 |
1.4 |
32,000 |
Pinheiro |
Measured |
|
|
|
|
Indicated |
|
|
|
|
Inferred |
2.0 |
1.0 |
0.7 |
20,000 |
Total |
2.0 |
1.0 |
0.7 |
20,000 |
NOA |
Measured |
|
|
|
|
Indicated |
0.4 |
1.2 |
0.8 |
4,200 |
Inferred |
0.3 |
1.0 |
0.9 |
2,900 |
Total |
0.6 |
1.1 |
0.9 |
7,100 |
All Deposits |
Measured |
6.6 |
1.1 |
0.7 |
71,600 |
Indicated |
6.8 |
1.0 |
0.8 |
65,400 |
Inferred |
10.2 |
1.0 |
0.9 |
103,900 |
Total |
23.5 |
1.02 |
0.8 |
241,000 |
(Note: Minor rounding discrepancies may occur)
Grandao Mineral Resource Estimate
The Grandao Deposit comprises two main pegmatite intrusions. The upper part of the deposit occurs within a broad, shallow dipping pegmatite body with a typical thickness of 20m-40m. The lower portion is a steep dipping dyke, which is 15m-20m in true width striking north south. In addition, minor parallel lenses of pegmatite are also included in the Mineral Resource Estimate. Both main pegmatite zones remain open either along strike or down plunge (Figure 4-6).
Figure 4. Grandao Resource Model coloured by resource classification (looking NE)
Figure 5. Cross Section (4608000N) through Grandao Resource Model (looking north)
*Cautionary Statement: The potential quantity and grade of the Exploration Targets is conceptual in nature, there has been insufficient exploration work to estimate a mineral resource and it is uncertain if further exploration will result in defining a mineral resource.
The Grandao Mineral Resource Estimate is based on results from 92 RC drill holes, 31 diamond holes and 25 RC holes with diamond tails completed by Savannah between 2017 and 2019.
Figure 6. Grandao Resource Model coloured by Li2O content (looking NE)
Potential Resource Expansion
The Grandao Deposit remains open both along strike in a number of directions, as well as, down dip. Given the consistency and predictability with which the drilling programme has been able to regularly intersect the main flat lying pegmatite, it is reasonable to interpret that further drilling could lead to an expansion of the Grandao Deposit (Figure 4).
Geology
At Mina do Barroso, lithium mineralisation occurs predominantly in the form of spodumene-bearing pegmatites, which are hosted in metapelitic and mica schists, and occasionally carbonate schists of upper Ordovician to lower Devonian age. The main Grandao pegmatite is a flat-lying, tabular zone defined over an area of 600m north-south and 980m east-west and varies in thickness from 10m-60m. It is very close to surface and is visible in outcrop over a significant area. A lower zone of mineralisation is also present at Grandao, hosted in a north-south trending steep-dipping, tabular pegmatite dyke 15m-20m in true width. (Figure 7).
Figure 7. Grandao Geological Model
At the Project, lithium is present in most pegmatite compositions and laboratory test work confirms that the lithium is almost exclusively within spodumene. Distinct lithium grade zonation occurs within the pegmatites, with weakly mineralised zones often evident at the margins of the dykes. Minor xenoliths and inliers of schist are observed within the main pegmatite. Where these have sufficient continuity, they have been separately modelled and excluded from the estimate.
The weathering profile at Grandao comprises a shallow, surficial zone of weak to moderate oxidation, particularly of the schistose country rock. A zone of deeper weathering exists on the western side of the Grandao Deposit with moderate oxidation to a depth of up to 50m.
Drilling
A total of 92 RC drill holes, 31 diamond holes and 25 RC holes with diamond tails were completed by Savannah between 2017 and 2019. The holes were drilled on an approximate grid spacing of 20m-60m with a number of closer spaced holes in the shallow part of the deposit.
Drill collar locations are recorded in Universal Traverse Mercator ("UTM") coordinates using differential GPS. All Savannah drilling has been down-hole surveyed using a gyroscopic tool.
Sampling and Sub-Sampling Techniques
For the Savannah RC drilling, a face-sampling hammer was used with samples collected at 1m intervals from pegmatite zones with composite sampling of typically 4m in the surrounding schists in early drilling. In recent drilling the schist 5m either side of the pegmatite was sampled at 1m intervals with the rest of schist remaining unsampled. The 1m samples were collected through a rig-mounted riffle splitter and were 4kg-6kg in weight. The 4m composites were collected by spear sampling of the 1m intervals. Samples were weighed to assess the sample recovery which was determined to be satisfactory.
Core was PQ and HQ in size and sampled to geological boundaries. Core was cut using a diamond saw, and for the majority of holes, half core was collected for assay. A number of diamond holes were sampled for metallurgical test work. For those holes, quarter core was submitted for assay.
Sample Analysis Method
For all Savannah drilling, whole samples were crushed then riffle split to produce a 250g split for pulverising and analysis.
The samples were analysed using ALS laboratories ME-MS89L Super Trace method which combines a sodium peroxide fusion with ICP-MS analysis and a multi-element suite was analysed.
Quality assurance / quality control ("QAQC") protocols were in place for the drilling programmes and included the used of blanks, standards and field duplicates. The data has confirmed the quality of the sampling and assaying for use in Mineral Resource estimation.
Estimation Methodology
For the Grandao Mineral Resource Estimate, a Surpac block model was constructed with block sizes of 10m (EW) by 20m (NS) by 5m (elevation) with sub-celling to 2.5m by 5m by 2.5m. The typical drill hole spacing is 20m-60m.
Interpretation of the pegmatite dykes was completed using detailed geological logging and Fe geochemistry. Wireframes of the pegmatites were prepared and within those the sample data was extracted and analysed. A clear break in the grade distribution occurs at 0.5% Li2O and this grade threshold was used to prepare the internal grade domains for estimation. In addition to the two main pegmatite bodies, several small pegmatites were also interpreted. Zones of unmineralised schist within the pegmatite body were selectively wireframed and excluded from the estimate.
Sample data was composited into 1m intervals then block model grades estimated using ordinary kriging ("OK") grade interpolation for the two main pegmatites and inverse distance squared ("ID2") grade interpolation for the small pegmatite zones. A first pass search range of 60m was used and oriented to match the dip and strike of the mineralisation. A minimum of 10 samples and a maximum of 24 samples were used to estimate each block. The majority of the Mineral Resource Estimate (71%) was completed in the first pass with expanded search radii of 120m and 240m used for the blocks not estimated in the first pass. No extreme high grades were present in the Li2O and Fe data, and the CV of less than 1 for all elements suggested that high grade cuts were not required. However, a small number of outliers of Ta were present in Domain 1 and a high grade cut of 60ppm was applied to all Ta values.
Iron within the pegmatites is uniformly low, with a mean Fe2O3 grade of 1.3% at Grandao. Test work by Savannah suggest that a large proportion of the assayed iron (approximately 40%) is due to contamination from the abrasion of steel sample preparation equipment. Results show a substantial and consistent difference between the Fe results from the different preparation equipment. The greatest difference is in the preparation of core samples, where it appears that the coarser nature of the particles may cause greater abrasion of the steel equipment and it was considered necessary to determine a correction factor to ensure reliable Fe values were applied to the Mineral Resource estimate.
The amount of Fe contamination was determined using the derived regression formula:Fe_contamination = (0.1734 * Li2O grade) + 0.2308.
A new field "Fe_factored" was inserted into the drill hole database, and the original Fe value minus the calculated contamination was stored in that field. This allowed a "Fe_factored" value to be extracted from the database and used for grade estimation in the Mineral Resource.
Bulk density determinations using the immersion method were carried out on 3,370 half core samples. Bulk density values applied to the estimates were 2.5t/m3 for oxide lithologies, 2.65t/m3 for unoxidised pegmatite and 2.67t/m3 for unoxidised schist.
Mineral Resource Classification
The Mineral Resource Estimate was classified in accordance with the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC, 2012).
The main pegmatite dyke at Grandao has generally been drilled at 40m to 60m holes spacings with a portion of the deposit drilled at closer spacings. The majority of holes in the main pegmatite at Grandao have consistently intersected pegmatite, with the majority intersecting resource grade Li2O mineralisation and the continuity of lithium mineralisation is good.
Due to the consistent drill hole spacing defining excellent continuity of lithology and mineralisation and accurate location data, the well drilled portion of the upper pegmatite has been classified as Measured Mineral Resource. This includes mineralisation drilled at 20m to 40m spacings where the pegmatite geometry is consistent and mineralisation is uniform.
The portion of the deposit defined by 40m to 60m spaced drill holes has been classified as Indicated Mineral Resource Estimate. Where the main pegmatite showed good potential for further extensions, the Indicated Mineral Resource Estimate was extrapolated up to 60m past drill hole intersections and the Inferred Mineral Resource Estimate was extrapolated a further 60m.
All minor pegmatite bodies were classified as an Inferred Mineral Resource Estimate due to the lack of detailed drilling or the uncertainty of geometry of the mineralisation.
The main shallow pegmatite at Grandao lies entirely above 250m vertical depth. The deep pegmatite has been reported to a depth of 230m vertical.
Cut-off Grades
The shallow and flat lying nature of the main Grandao pegmatite suggests good potential for open pit mining if sufficient resources can be delineated to consider a mining operation. As such, the Mineral Resource Estimate has been reported at a 0.5% Li2O lower cut-off grade to reflect assumed exploitation by low-cost mining methods.
Metallurgy
Metallurgical test work has been conducted by Savannah on representative mineralisation at Mina do Barroso. The work was completed by Nagrom Metallurgical in Australia and confirmed that high-grade lithium, low-grade iron concentrate can be generated from the mineralisation using conventional processing technology. Microscopy confirmed that the concentrate was almost entirely spodumene. A substantial metallurgical test work programme is ongoing to define to determine an optimised flow sheet.
Modifying Factors
No modifying factors were applied to the reported Mineral Resource Estimate. Parameters reflecting mining dilution, ore loss and metallurgical recoveries will be considered during the any future mining evaluation of the Project.
Pinheiro Mineral Resource Estimate
The Pinheiro Deposit comprises a cluster or swarm of pegmatite bodies striking broadly NS and dipping steeply to the east. The orientation and extent of two of the pegmatites have been sufficiently defined by drilling for resource estimation. The pegmatites have been defined over a strike of 250m with an average thickness of 10m-20m. The pegmatite mineralisation is predominantly fresh with a shallow weathering profile affecting the material 10-20m below surface. Both main pegmatite zones remain open either along strike or down plunge (Figure 8-10).
Figure 8. Grandao Resource Model coloured by resource classification (looking NE)
Figure 9. Pinheiro Cross Section (4606850N) (looking north)
The Pinheiro Mineral Resource Estimate is based on results from 10 RC drill holes and 2 diamond holes completed by Savannah in 2018 and both modeled pegmatite zones remain open either along strike or down dip.
Figure 10. Pinheiro Resource Model coloured by Li2O content (looking North)
Geology
At Mina do Barroso, lithium mineralisation occurs predominantly in the form of spodumene-bearing pegmatites, which are hosted in metapelitic and mica schists, and occasionally carbonate schists of upper Ordovician to lower Devonian age.
The Pinheiro pegmatites are a swarm of steeply dipping tabular dykes defined over an area of 250m north-south with a dip extent of 160m. The dykes vary in thickness from 10m-20m and are typically mineralised across the full width. The pegmatites are very close to surface and visible in outcrop over a significant area (Figure 11).
Figure 11. Pinheiro Geological Model and Mapped Pegmatites
At the Project, lithium is present in most pegmatite compositions and laboratory test work confirms that the lithium is almost exclusively within spodumene. Limited lithium grade zonation occurs within the Pinheiro pegmatites. Minor xenoliths and inliers of schist are observed within the pegmatite.
The weathering profile comprises a shallow, surficial zone of weak to moderate oxidation, particularly of the schistose country rock with moderate oxidation to a depth of up to 20m.
Drilling
A total of 19 RC drill holes and 2 diamond holes were completed by Savannah in 2018. The holes were drilled on an approximate grid spacing of 20m-60m.
Drill collar locations are recorded in Universal Traverse Mercator ("UTM") coordinates using differential GPS. All Savannah drilling has been down-hole surveyed using a gyroscopic tool.
Sampling and Sub-Sampling Techniques
For the Savannah RC drilling, a face-sampling hammer was used with samples collected at 1m intervals from pegmatite zones and the surrounding 5m either side of the pegmatite was with the rest of schist remaining unsampled. The 1m samples were collected through a rig-mounted riffle splitter and were 4kg-6kg in weight. Samples were weighed to assess the sample recovery which was determined to be satisfactory.
Core was PQ in size and sampled to geological boundaries. Core was cut using a diamond saw, and quarter core was collected for assay with the remaining sampled for metallurgical test work.
Sample Analysis Method
For all Savannah drilling, whole samples were crushed then riffle split to produce a 250g split for pulverising and analysis.
The samples were analysed using ALS laboratories ME-MS89L Super Trace method which combines a sodium peroxide fusion with ICP-MS analysis and a multi-element suite was analysed.
QAQC protocols were in place for the drilling programmes and included the used of blanks, standards and field duplicates. The data has confirmed the quality of the sampling and assaying for use in Mineral Resource estimation.
Estimation Methodology
For the Pinheiro Mineral Resource Estimate, a Surpac block model was constructed with block sizes of 5m (EW) by 20m (NS) by 5m (elevation) with sub-celling to 1.25m by 5m by 1.25m. The typical drill hole spacing is 40m-60m.
Interpretation of the pegmatite dykes was completed using detailed geological logging and Fe geochemistry. Wireframes of the pegmatites were prepared and within those the sample data was extracted and analysed. A clear break in the grade distribution occurs at 0.35% Li2O and this grade threshold was used to prepare the internal grade domains for estimation. In addition to the two main pegmatite bodies.
Sample data was composited into 1m intervals then block model grades estimated using inverse distance squared ("ID2") grade interpolation due to the small number of drill holes and limited extent of mineralisation. A first pass search range of 50m was used and oriented to match the dip and strike of the mineralisation. A minimum of 10 samples and a maximum of 24 samples were used to estimate each block. The majority of the Mineral Resource Estimate (66%) was completed in the first pass with expanded search radii of 100m and 200m used for the blocks not estimated in the first pass. No extreme high grades were present in the Li2O and Fe data, and the CV of less than 1 for all elements suggested that high grade cuts were not required. However, a small number of outliers of Ta were present at Pinheiro and a high grade cut of 60ppm was applied to all Ta values.
Iron contamination has been reported from other lithium projects, where iron is introduced into the samples via abrasion of RC drilling equipment and/or sample preparation equipment. To test the potential for iron contamination at the MBLP, SAV carried out a preliminary program of check assays and a series of comparisons were undertaken on samples from the Grandao deposit.
It was concluded from the Grandao study that a significant proportion of the iron being reported in the drilling assay data was introduced as contamination during the sample preparation process. It was determined that the amount of contamination was proportional to the lithium content of the samples. A regression formula was calculated using all samples, with the derived regression formula being:
Fe_contamination = (0.1734 * Li2O grade) + 0.2308.
The amount of Fe contamination was determined using the derived regression formula. A new field "Fe_factored" was inserted into the drill hole database, and the original Fe value minus the calculated contamination was stored in that field. This allowed a "Fe_factored" value to be extracted from the database and used for grade estimation in the Mineral Resource.
Extensive bulk density determinations using the immersion method were carried out on 3,370 half core samples from the Grandao deposit. Results from these tests were applied to the Pinheiro mineralisation. Values applied to the estimates were 2.5t/m3 for oxide lithologies, 2.65t/m3 for unoxidised pegmatite and 2.67t/m3 for unoxidised schist.
Mineral Resource Classification
The Mineral Resource Estimate was classified in accordance with the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC, 2012).
Mineral Resource classification was considered on the basis of drill hole spacing, continuity of mineralisation and data quality. The continuity of the Pinheiro pegmatite is not well defined with patchy outcrop and multiple intrusions. Accurate drill hole collar and topographic surveys have been obtained for the deposit, so the spatial location of data and topography has a high level of confidence. The quality of the drilling and assaying has been confirmed through independent verification of procedures and through a satisfactory QAQC protocol.
Due to the uncertainty in the interpreted geometry of the mineralisation and the sparse drilling at the deposit, the entire deposit was classified as Inferred Mineral Resource.
Cut-off Grades
The shallow nature of the main Grandao pegmatite suggests good potential for open pit mining if sufficient resources can be delineated to consider a mining operation. As such, the Mineral Resource Estimate has been reported at a 0.5% Li2O lower cut-off grade to reflect assumed exploitation by low-cost mining methods.
Metallurgy
Metallurgical test work has been conducted by Savannah on representative mineralisation at Mina do Barroso. The work was completed by Nagrom Metallurgical in Australia and confirmed that high-grade lithium, low-grade iron concentrate can be generated from the mineralisation using conventional processing technology. Initial assessments of the mineralogy and chemistry suggest mineralisation is broadly similar to other deposits at Mina do Barroso. Samples have been collected from the Pinheiro deposit are currently being tested to determine their exact processing requirement.
Modifying Factors
No modifying factors were applied to the reported Mineral Resource Estimate. Parameters reflecting mining dilution, ore loss and metallurgical recoveries will be considered during the any future mining evaluation of the Project.
NOA Mineral Resource Estimate
The NOA Deposit is hosted in steep dipping NW trending tabular pegmatite which has a true width of 5-10m thick. The estimate is based on results from 22 RC and two diamond drill holes all completed by Savannah in 2017 and 2018. The deposit outcrops over a strike length of approximately 420m and remains open along strike and at depth. (Figure 12-14).
Figure 12. NOA Resource Model coloured by Li2O% (looking west)
Figure 13. NOA Cross Section (4606850N) (looking north)
Figure 14. NOA Resource Model coloured Resource Classification (looking West)
Geology
At Mina do Barroso, lithium mineralisation occurs predominantly in the form of spodumene-bearing pegmatites, which are hosted in metapelitic and mica schists, and occasionally carbonate schists of upper Ordovician to lower Devonian age.
At the NOA deposit, the host pegmatite is a steep dipping, NW trending body which is 5-10m in true width. It has been mapped in outcrop over much of the interpreted 420m strike length of the Mineral Resource (Figure 15). The weathering profile comprises a shallow, surficial zone of weak to moderate oxidation, particularly of the schistose country rock. A weathering surface representing the top of fresh rock ("TOFR") was used to define the transitional and fresh mineralisation.
Figure 15: NOA pegmatite wireframes and drilling
At the Project, lithium is present in most pegmatite compositions and laboratory test work confirms that the lithium is almost exclusively within spodumene. Limited lithium grade zonation occurs within the NOA pegmatites. Minor xenoliths and inliers of schist are observed within the pegmatite.
Drilling
A total of 25 RC drill holes and 2 diamond holes were completed by Savannah in 2017 and 2018. The holes were drilled on an approximate grid spacing of 20m-40m.
Drill collar locations are recorded in Universal Traverse Mercator ("UTM") coordinates using differential GPS. All Savannah drilling has been down-hole surveyed using a gyroscopic tool.
Sampling and Sub-Sampling Techniques
For the Savannah RC drilling, a face-sampling hammer was used with samples collected at 1m intervals from pegmatite zones and the surrounding 5m either side of the pegmatite was with the rest of schist remaining unsampled. The 1m samples were collected through a rig-mounted riffle splitter and were 4kg-6kg in weight. Samples were weighed to assess the sample recovery which was determined to be satisfactory.
Core was PQ in size and sampled to geological boundaries. Core was cut using a diamond saw, and quarter core was collected for assay with the remaining sampled for metallurgical test work.
Sample Analysis Method
For all Savannah drilling, whole samples were crushed then riffle split to produce a 250g split for pulverising and analysis.
The samples were analysed using ALS laboratories ME-MS89L Super Trace method which combines a sodium peroxide fusion with ICP-MS analysis and a multi-element suite was analysed.
QAQC protocols were in place for the drilling programmes and included the used of blanks, standards and field duplicates. The data has confirmed the quality of the sampling and assaying for use in Mineral Resource estimation.
Estimation Methodology
For the NOA Mineral Resource Estimate, a Surpac block model was constructed with block sizes of 20m (EW) by 5m (NS) by 5m (elevation) with sub-celling to 5m by 1.25m by 1.25m. The typical drill hole spacing is 20m-40m.
Interpretation of the pegmatite dykes was completed using detailed geological logging and Fe geochemistry. Wireframes of the pegmatites were prepared and within those the sample data was extracted and analysed. A clear break in the grade distribution occurs at 0.35% Li2O and this grade threshold was used to prepare the internal grade domains for estimation.
Sample data was composited into 1m intervals then block model grades estimated using inverse distance squared ("ID2") grade interpolation due to the small number of drill holes and limited extent of mineralisation. A first pass search range of 50m was used and oriented to match the dip and strike of the mineralisation. A minimum of 10 samples and a maximum of 24 samples were used to estimate each block. The majority of the Mineral Resource Estimate (82%) was completed in the first pass with expanded search radii of 100m used for the blocks not estimated in the first pass. No extreme high grades were present in the Li2O and Fe data, and the CV of less than 1 for all elements suggested that high grade cuts were not required. However, a small number of outliers of Ta were present at Pinheiro and a high grade cut of 100ppm was applied to all Ta values.
Iron contamination has been reported from other lithium projects, where iron is introduced into the samples via abrasion of RC drilling equipment and/or sample preparation equipment. To test the potential for iron contamination at the MBLP, SAV carried out a preliminary program of check assays and a series of comparisons were undertaken on samples from the Grandao deposit.
It was concluded from the Grandao study that a significant proportion of the iron being reported in the drilling assay data was introduced as contamination during the sample preparation process. It was determined that the amount of contamination was proportional to the lithium content of the samples. A regression formula was calculated using all samples, with the derived regression formula being:
Fe_contamination = (0.1734 * Li2O grade) + 0.2308.
The amount of Fe contamination was determined using the derived regression formula. A new field "Fe_factored" was inserted into the drill hole database, and the original Fe value minus the calculated contamination was stored in that field. This allowed a "Fe_factored" value to be extracted from the database and used for grade estimation in the Mineral Resource.
Extensive bulk density determinations using the immersion method were carried out on 3,370 half core samples from the Grandao deposit. Results from these tests were applied to the Pinheiro mineralisation. Values applied to the estimates were 2.5t/m3 for oxide lithologies, 2.65t/m3 for unoxidised pegmatite and 2.67t/m3 for unoxidised schist.
Mineral Resource Classification
The Mineral Resource Estimate was classified in accordance with the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC, 2012).
At NOA, the continuity of the controlling pegmatite appears to be good. Where the pegmatite is exposed, the interpretation is supported by mapped contacts at surface and within the small pit being mined. The portion of the NOA pegmatite defined by 40m to 60m spaced drill holes and showing good continuity of pegmatite and Li2O distribution has been classified as Indicated Mineral Resource. The Indicated portion was extended for the full length of the pegmatite which had been exposed and mapped in the pit and was extrapolated up to 30m past drill hole intersections. Inferred Mineral Resource was assigned to those areas of the NOA deposit defined by a drill hole spacing of greater than 60m.
Cut-off Grades
The shallow nature of the main NOA pegmatite suggests good potential for open pit mining if sufficient resources can be delineated to consider a mining operation. As such, the Mineral Resource Estimate has been reported at a 0.5% Li2O lower cut-off grade to reflect assumed exploitation by low-cost mining methods.
Metallurgy
Metallurgical test work has been conducted by Savannah on representative mineralisation at Mina do Barroso. The work was completed by Nagrom Metallurgical in Australia and confirmed that high-grade lithium, low-grade iron concentrate can be generated from the mineralisation using conventional processing technology. Initial assessments of the mineralogy and chemistry suggest mineralisation at NOA is broadly similar to other deposits at Mina do Barroso. Samples have been collected from the NOA deposit are currently being tested to determine their exact processing requirements.
Modifying Factors
No modifying factors were applied to the reported Mineral Resource Estimate. Parameters reflecting mining dilution, ore loss and metallurgical recoveries will be considered during the any future mining evaluation of the Project.
Exploration Target*
Savannah has defined a Mineral Resource Estimate from four deposits in the Mina do Barroso Project area (Table 5). All four deposits remain open and untested by drilling either down dip or along strike of the defined Mineral Resource Estimate and there is excellent potential to extend the deposits with further drilling. In addition, there are numerous other outcropping pegmatite dykes that require drill testing to determine if they are also lithium bearing.
Savannah has been drilling at Mina do Barroso since mid-2017 and ongoing programmes in 2018 and 2019 are designed to test for extensions of the defined deposits and to test other outcropping pegmatite targets in the Project area. The drilling at the Grandao deposit has been very successful and has allowed a major increase to the reported Mineral Resource Estimate, as well as, increasing confidence in the estimate. Infill drilling at NOA has allowed the confidence in a significant portion of the Mineral Resource Estimates to be increased to Indicated.
To quantify the potential of the Project beyond the currently defined Mineral Resource Estimates, an Exploration Target* for the Grandao and Reservatorio Deposits of 9-15Mt at 1.0% to 1.2% Li₂O. This gives a project target (including Mineral Resource Estimate) of 32-38Mt at 1.0-1.2% Li₂O. Importantly, this exploration target only includes Grandao and Reservatorio with further upside remaining from the many other high priority exploration prospects within the project area.
Table 4. Exploration Targets* for Mina do Barroso Project
Deposit |
Tonnage Range (Mt) |
Li2O5 % |
Lower |
Upper |
|
Reservatorio |
|
|
|
Bottom of Inferred to 200m Vertical Depth |
5.0 |
7.0 |
1.0-1.2% |
Grandao |
|
|
|
200m-400m Extension of Upper Pegmatite |
3.0 |
6.0 |
1.0-1.2% |
100% Expansion of Lower Pegmatite |
1.0 |
2.0 |
1.0-1.2% |
Total Mina do Barroso Exploration Target |
9.0 |
15.0 |
1.0-1.2% |
*Cautionary Statement: The potential quantity and grade of the Exploration Targets is conceptual in nature, there has been insufficient exploration work to estimate a mineral resource and it is uncertain if further exploration will result in defining a mineral resource.
Reservatorio Exploration Target*
A Mineral Resource Estimate was completed for the Reservatorio Deposit in December 2017. It was modelled and estimated for the full extent of the SAV drilling and the Inferred Mineral Resource Estimate was extended between 40m and 100m down dip from the deepest drill holes.
There is no information to suggest that the pegmatite and lithium mineralisation does not continue with the same characteristics and grade as the drilled portion. As a result, beneath the Inferred Mineral Resource Estimate boundary, a wireframe model was created, assuming continuation of the mineralisation down-dip to 200m below surface. Applying a density of 2.6t/m3 as used in the Reservatorio Inferred Mineral Resource Estimate, and assuming the same lithium grade observed in the drilled portion, the Exploration Target has been defined as 5 Mt to 7 Mt at a grade of 1.0% to 1.2% Li2O.
Grandao Exploration Target*
The current Mineral Resource Estimate was completed for the Grandao Deposit in April 2019. It was modelled and estimated for the area drilled in detail by SAV. The Inferred Mineral Resource Estimate was extended up to 120m down plunge from drilled area.
The shallow pegmatite appears to be closed off by drilling to the northeast and to the southeast. To the west and northwest and south, the mineralisation remains open and untested the limits of the mineralisation have not been found. There is no information to suggest that the pegmatite and lithium mineralisation does not continue to the west and northwest with the same characteristics and grade as the drilled portion and the strong results from the recent drilling has confirmed this.
The Exploration Target* for the shallow pegmatite is considered to be at least a 200m-400m down-plunge extension of the defined Mineral Resource Estimate for that portion of the deposit so the Exploration Target has been defined as 3 Mt to 6 Mt at a grade of 1.0% to 1.2% Li2O. This represents a 20%-40% increase on the currently defined Mineral Resource.
The steep pegmatite has been intersected in a small number of holes which have recorded thick, high grade mineralisation. The mineralisation is open in most directions and the Exploration Target has been defined as a 100% increase on the defined Mineral Resource Estimate which gives an Exploration Target of 1 Mt to 2 Mt at a grade of 1.0% to 1.2% Li2O.
*Cautionary Statement: The potential quantity and grade of the Exploration Targets is conceptual in nature, there has been insufficient exploration work to estimate a mineral resource and it is uncertain if further exploration will result in defining a mineral resource.
Competent Person and Regulatory Information
The information in this announcement that relates to exploration results is based upon information compiled by Mr Dale Ferguson, Technical Director of Savannah Resources Limited. Mr Ferguson is a Member of the Australasian Institute of Mining and Metallurgy (AusIMM) and has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the December 2012 edition of the "Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves" (JORC Code). Mr Ferguson consents to the inclusion in the report of the matters based upon the information in the form and context in which it appears.
The Information in this report that relates to Mineral Resources is based on information compiled by Mr Paul Payne, a Competent Person who is a Fellow of the Australasian Institute of Mining and Metallurgy. Mr Payne is a full-time employee of Payne Geological Services. Mr Payne has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the "Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves". Mr Payne consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
This announcement contains inside information for the purposes of Article 7 of Regulation (EU) 596/2014.
**ENDS**
For further information please visit www.savannahresources.com or contact:
David Archer |
Savannah Resources plc |
Tel: +44 20 7117 2489 |
David Hignell / Charlie Bouverat (Nominated Adviser) |
SP Angel Corporate Finance LLP |
Tel: +44 20 3470 0470 |
Christopher Raggett (Broker) |
finnCap Ltd |
Tel: +44 20 7220 0500 |
Grant Barker (Equity Adviser) |
Whitman Howard |
Tel: +44 20 7659 1225 |
Melissa Hancock/ Cosima Akerman (Financial PR) |
St Brides Partners Ltd |
Tel: +44 20 7236 1177 |
About Savannah
Savannah is a diversified resources group (AIM: SAV) with a portfolio of energy metals projects - lithium in Portugal and copper in Oman - together with the world-class Mutamba Heavy Mineral Sands Project in Mozambique, which is being developed in a consortium with the global major Rio Tinto. The Board is committed to serving the interests of its shareholders and to delivering outcomes that will improve the lives of the communities we work with and our staff.
The Company is listed and regulated on AIM and the Company's ordinary shares are also available on the Quotation Board of the Frankfurt Stock Exchange (FWB) under the symbol FWB: SAV, and the Börse Stuttgart (SWB) under the ticker "SAV".