BSE Base Resources Limited

AIM and Media Release 

8 May 2023

BASE RESOURCES LIMITED
Tanzanian exploration – Umba South Phase 1 drill results

Key Points

• Phase 1 reverse circulation drilling program completed at the Umba South prospect in northern Tanzania, with 3,015m in 122 holes drilled.
• Assay results confirm the presence of rutile mineralisation, which averages approximately 20% of the heavy mineral but is highly variable and can range from 5 to 50% of the heavy mineral.
• Three primary geological domains were identified:
  • Soil/colluvial cover sequence (the primary exploration target) – typically quite thin (~1-2m) but can be locally up to 9m thick and has demonstrated widespread rutile mineralisation.
  • Underlying saprolite material – variable thickness with sporadic rutile mineralisation, and does not appear to be sufficiently weathered to represent free-dig material from which rutile is readily liberated.
  • Bedrock - heavy mineral content is variable but typically high grade (~20%); however it is dominated by pyrite - a known deleterious element for mineral sands processing, requiring dedicated tailings handling and storage.
• Preliminary mineralogical assessment of drill samples is yet to be completed, with the presence of rutile calculated based on XRF analysis of the non-magnetic fraction of heavy mineral.
• While graphite is present in some drill samples, analysis suggests the overall grade and distribution of mineralisation is not significant.
• A Phase 2 infill drilling program to assess the continuity of saprolite mineralisation has been completed, with the results expected to be available in the September 2023 quarter.  These results will assist in planning future exploration activity at Umba South and elsewhere along the prospective geological zone once necessary approvals are obtained.

Base Resources Limited (ASX & AIM: BSE) (Base Resources or the Company) is pleased to provide assay results from the first phase of drilling at its Umba South Project (Umba South) in northern Tanzania (Phase 1). 

Figures referenced in this release have been omitted.  A full PDF version of this release, including all figures, is available from the Company’s website:  www.baseresources.com.au.  A glossary of key terms used in this release is set out at the end of this release.  

Location of Phase 1 drilling and other exploration activities 

Umba South is located near the junction of the Umba and Bombo Rivers in northern Tanzania, approximately 75km west-south-west of the Company’s Kwale Operations in Kenya (refer to Figure 1).  Exploration at Umba South was designed to test the southern extremity of a prominent north-south trending ridge of quartzite and gneiss that extends 35km north to the Kuranze region of Kenya, where initial rock chip and soil sampling indicated the presence of rutile.  With the Company unable to carry out exploration activities in Kuranze due to its prospecting licence applications for that area being on hold following the Government of Kenya’s ongoing moratorium on issuance of new mineral rights, efforts were instead directed to the southern portion of the ridge in Tanzania.  

Exploration activity in Tanzania has so far been confined to areas south of the Umba River, while the Company seeks to obtain the necessary approvals from various government departments to explore in the Mkomazi Game Controlled Area to the north which hosts the target ridge feature extending north to the Kenyan border (refer to Figure 2).

Details about exploration activities

Exploration at Umba South targeted a high-grade metamorphic sequence within the Mozambique Belt that comprises paragneiss (quartzo-feldspathic gneiss) and sillimanite-kyanite(-garnet) schists.  The sequence includes accessory minerals pyrite, rutile, magnetite and graphite, with rutile the primary exploration target.  The focus of exploration is secondary rutile mineralisation associated with alluvial and colluvial deposits eroding from the outcropping linear ridges of pyritic quartz-feldspar gneiss, and primary rutile mineralisation within the weathered saprolite material flanking the ridge feature that is sufficiently weathered to represent free-dig material from which rutile can be readily liberated.

In early 2022, mechanised auger sampling of the soil profile to approximately 1m depth on a 500m x 500m sample grid was undertaken across the broader tenement area, with the best results (up to 5% rutile) reported from the flanks of Kigwase Hill.  In the June quarter of 2022, rockchip sampling of the outcropping ridge confirmed the presence of rutile mineralisation, with grades of up to 2.5% rutile reported from banded gneiss on Kigwase Hill.  Selected rockchip samples were sent for mineralogical analysis, and this confirmed the presence of rutile together with pyrite (in fresh samples), Fe-oxides (in weathered samples), magnetite and altered ilmenite.

A series of test pits were then completed to assess the soil profile, including the nature of contact with the underlying saprolite.  Mapping suggests that red-brown soil is typically developed within rubbly colluvium overlying the brown saprolite material.  Pit depths ranged from 1.5m to 6.5m and samples of material collected from the test pits were processed at the Kwale Operations laboratory.  Encouraging results were obtained from several samples with potential HM products of rutile, leucoxene, altered ilmenite and magnetite generated using conventional mineral sands processing techniques.  One of the test pits, pit 11, was investigated in detail and reported in-situ grades of approximately 1% rutile, 1% leucoxene-altered ilmenite and 1% magnetite (refer to Figure 2).

Following the encouraging results from the reconnaissance exploration, the Phase 1 program was planned to obtain preliminary data regarding the sub-surface geology and rutile mineralisation in the vicinity of Kigwase Hill.  A 400m North-South x 200m East-West reconnaissance grid was subsequently drilled over Kigwase Hill where access was available, with the terrain and the presence of small-scale gemstone tenure (known as primary mining licences) restricting complete coverage (refer to Figure 3 for the drill hole collar locations).  A total of 122 holes were drilled for 3,015m using a RC drill rig with a hammer bit, primarily due to lack of available aircore drill rigs and concerns regarding the ability of aircore to penetrate both the rubbly colluvium and the saprolite.  As a result of the drill samples being mechanically pulverised by the hammer bit, the slimes content of samples is likely to be overstated, the oversize content is likely understated, and the sand fraction likely contains mechanically generated sand together with natural sand.

Results from Phase 1 drilling

The sample analysis for rutile has been completed on the sand fraction using conventional mineral sands techniques (and back-calculated for in-situ grades).  There is the potential that rutile assays reported may not reflect true in-situ grade and/or represent rutile that is readily amenable to conventional mineral sands processing.  Analysis of selected oversize fractions confirmed significant rutile is present in the oversize.  For holes TN092 to TN122, the oversize fraction from the first stage of sample processing was crushed and added to the sand fraction prior to HM analysis – such that these holes report a “total” rutile grade (assuming no loss to the slimes fraction), whereas holes TN001 to TN091 report only the rutile from the sand fraction and may therefore only be a “partial” rutile grade.

Drill logging has identified three primary geological domains, as follows:

• Red-brown soil and colluvium with abundant gravel – typically 1-2m thick on the eastern flank of Kigwase Hill and 2-4m thick on the western flank of Kigwase Hill.  Consistently mineralised and reports high levels of ferruginous HM and significant TiO₂ in the magnetic fraction.  The HM is enriched in the upper part of the profile.  This domain is confirmed as a viable exploration target for the province, but lacks the depth/thickness at Umba South to have significant economic potential.
• Brown saprolite and saprock – weathered bedrock, subdivided into sandy and clayey units.  It is thought that this reflects the protolith (quartz rich vs feldspar rich), rather than weathering intensity as there is limited evidence for a well-developed chemical weathering profile with remobilisation and volume reduction.  Depth of weathering ranges down to 50m but is typically ~30m distal to the ridge, and localised variability is evident.  The HM content is highly variable, and often variable HM magnetic fractions both down and between holes.  The saprolite is considered a viable exploration target for the province, but at Umba South it appears to lack the consistent intense weathering that concentrates rutile in the upper profile and promotes free dig mining and simple processing.
• Grey bedrock – fresh gneiss, typically with abundant pyrite.  Garnet gneiss logged distal to the ridge, but logging has not attempted to classify the bedrock lithology in detail.  The HM content is variable but typically high grade (~20% HM) although dominated by pyrite.  The bedrock is not considered a viable exploration target for rutile due to cost and complexity that would be introduced by hard rock mining and comminution, and the negative impact of pyrite mineralisation on mineral processing recoveries and tails storage – with results only reported for geological interest.

Set out in the table below are notable hole intercepts.  Due to the variability of mineralisation between the geological domains – and potential mining, mineral processing and tailings handling and storage implications – the rutile mineralisation has been reported by domain and not by total hole intercepts.  For a list of all Phase 1 assay results, refer to Table 1 in Appendix 1.  Refer also to the cross sections in Figures 4 to 6 for a detailed rutile HM analysis of each drill hole.

Graphite is a common accessory mineral within the paragneiss sequence being explored and is routinely observed during panning and logging of the drill samples.  Approximately 320 samples from all geological domains were randomly selected for analysis to assess the graphite mineralisation potential, with around a third of samples reporting below detection and the remainder averaging around 0.5% Total Graphitic Carbon including peak values up to 2.5% TGC.  The graphite mineralisation is not typically coincident with rutile mineralisation and appears confined to specific stratigraphic units within the drilled sequence.  Preliminary assessment suggests that graphite does not represent a viable exploration target due to unfavourable grade and distribution of mineralisation but may have value as a potential co-product where it occurs coincident with rutile.

For further details in respect of the results, refer to the Appendices to this release, containing a table of all assay results (refer to Appendix 1) and information provided for the purposes of Sections 1 and 2 of Table 1 of the JORC Code (refer to Appendix 2).

Phase 2 infill drilling and further planned activities

With the Phase 1 program drill spacing unable to establish geological and grade continuity of saprolite mineralisation, an infill drilling program was undertaken in the first quarter of 2023, with 86 holes drilled for 2,128m (Phase 2).  Assay results from Phase 2 are expected to be available in the September quarter of 2023, due to delays associated with the export of samples from Tanzania to Kenya and prioritisation of operational assay requirements and near-mine exploration assays at the Kwale Operations laboratory.  The Phase 2 results should provide the Company with a more fulsome understanding of the Umba South mineralisation, which will assist in planning future exploration activity at Umba South and elsewhere along the prospective geological zone.

Other further work planned includes:

• Geostatistical assessment of data to establish grade continuity parameters.
• A program of shallow trenching to expose the saprolite and conduct rock chip channel sampling, geological mapping, and collection of saprolite samples to assess physical properties related to mining and processing characteristics.
• Seek to progress approvals to allow exploration access to granted prospecting licences north of the Umba River, particularly PL11686/2021, and conduct reconnaissance exploration in this area to establish if broad areas of rutile mineralisation are present within either colluvial/alluvial material shedding from the prospective ridge line, or strongly weathered saprolite associated with the targeted prospective zone.

Competent Person’s Statement

The information in this release that relates to the Umba South exploration results is based on, and fairly represents, information and supporting documentation prepared by Mr. Ian Reudavey.  Mr. Reudavey is a member of the Australasian Institute of Geoscientists.  Mr. Reudavey is employed by Base Resources.  Mr. Reudavey has sufficient experience that 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 JORC Code and as Qualified Person for the purposes of the AIM Rules for Companies.  Mr. Reudavey has reviewed this release and consents to the inclusion in this release of the Umba South exploration results and the supporting information in the form and context in which the relevant information appears.

Appendix 1

Table 1: Umba South Exploration Project drill hole table.  All drill holes have dip of -90 degrees and azimuth of 360 degrees (i.e. vertical).

Appendix 2

JORC Code, 2012 Edition

Section 1 Sampling Techniques and Data

Section 2 Reporting of Exploration Results

Glossary

ENDS.

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About Base Resources

Base Resources is an Australian based, African focused, mineral sands producer and developer with a track record of project delivery and operational performance.  The Company operates the established Kwale Operations in Kenya, is developing the Toliara Project in Madagascar and is conducting exploration in Tanzania.  Base Resources is an ASX and AIM listed company.  Further details about Base Resources are available at www.baseresources.com.au.

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