Musensi Hill surface sampling update

In brief · summary, not quotable

First-pass surface sampling at Musensi Hill block confirms high-grade potassium and rare earth enrichment in south-west Tanzania.

Potassium-bearing unit mapped extent approximately 3 km²
Licence area approximately 11 km²
Samples returned more than 10% K₂O 43 of 54
Median K₂O grade 13.5% K₂O
Highest potassium result 16.8% K₂O
Highest TREO result 3.76% TREO

Full announcement

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High-grade potassium and associated rare earth enrichment confirmed by first-pass surface sampling at the Musensi Hill block, south-west Tanzania

Amigo Resources PLC (LSE:AMGO), a company focused on gold and rare earth mining opportunities in Africa, is pleased to report the results of a first-pass surface sampling and petrographic programme over its Musensi Hill block (Licence No. PL 12668/2024) in the Songwe Region of south-west Tanzania. The work has identified a laterally extensive, potassium-rich alkaline volcanic unit - a phonolitic leucitite covering approximately 3 km² within the licence area of approximately 11 km² - carrying a coincident rare earth, strontium, barium and phosphate signature associated with later carbonate veining. Exploration is being carried out on the Company's behalf by Geovale Global FZ LLC.

Highlights

●	Consistently high potassium, well dispersed across the block: Of 54 samples of the alkaline suite, distributed across the mapped extent of the unit rather than clustered at one locality, 43 returned more than 10% K₂O, 30 more than 13% K₂O and 10 more than 15% K₂O. The median is 13.5% K₂O and the highest individual result 16.8% K₂O.
●	A defined mappable host: The potassium-bearing unit is a silica-undersaturated phonolitic leucitite, interpreted as a sequence of extrusive volcanic flows, presently mapped over approximately 3 km². Sampling to date covers a ground extent of about 2.2 km by 4.1 km.
●	Potassium in a reactive mineral form: Petrography on 14 thin sections indicates the potassium is carried principally in feldspathoid (leucite) rather than in potassium feldspar. Feldspathoids release potassium in soil far more readily than feldspar, which is the property that governs suitability as a silicate potassium (remineraliser) fertiliser feedstock .
●	Rare earth enrichment tied to carbonate veining: Fourteen of 54 samples returned more than 0.2% total rare earth oxide (TREO), four more than 0.5% TREO and one 3.76% TREO. Magnet rare earths (Nd, Pr, Dy, Tb) make up a median 17% of the contained TREO .
●	A coherent pathfinder signature: The rare earth results are accompanied by strontium to 7,333 ppm, barium to 15,788 ppm and phosphate to 2.11% P₂O₅, and are statistically tied to the carbonate veining rather than scattered at random. This gives the next programme a defined vector to follow.
●	Next phase approved: Detailed geological mapping, high-resolution ground magnetics and radiometrics, and systematic surface sampling will be undertaken to define the extent and controls of both the potassium and the rare earth systems, ahead of a resource drilling programme.

The results

Sixty rock samples were collected across the block and analysed for 67 elements, including the full rare earth suite, by Shiva Analyticals (India) Private Limited under certificate G6328. Fifty-four samples represent the potassic alkaline volcanic suite and six the surrounding gneissic basement. Major oxide totals close between 99.4% and 99.9%, and the dataset has been independently checked against the laboratory certificate.

The potassium tenor is the most consistent feature of the block. Grades above 13% K₂O were returned from samples spread across the sampled area rather than from a single locality, and sodium is correspondingly low, with a median Na₂O of 0.20% in the potassium-rich population, giving a median K₂O to Na₂O ratio above 60. Mineralogically, the rock is a silica-undersaturated phonolitic leucitite, interpreted by the Company's geologists as extrusive volcanic flows. The Company notes that this is a potassium silicate rock and not a conventional potash (chloride or sulphate) salt deposit; the potential application under evaluation is as a direct application remineraliser feedstock, and no metallurgical or agronomic test work has yet been undertaken.

The rare earth results are more localised and, at this stage, subordinate to the potassium. They occur where carbonate veins, interpreted to post-date the phonolitic leucitite, cut the volcanic pile and the underlying basement. The single 3.76% TREO result is an isolated high and should not be taken as representative; the median across the alkaline suite is 0.12% TREO. The Company's view is that the rare earths mark a leakage signal from a source at depth rather than a surface accumulation, and the purpose of the next phase is to establish whether that source exists, how large it is and how deep it lies.

Next steps

The Company has approved a programme of detailed geological mapping, high-resolution ground magnetics and radiometrics, and systematic, regularly spaced surface sampling across the block. The radiometric survey will map the potassium blanket and, through the thorium channel, the rare earth footprint directly and at a density that sixty grab samples cannot achieve. Magnetics, supported by gravity, will test for a buried intrusive source and provide an estimate of its depth. Subject to those results, a resource drilling programme would follow. No decision to mine has been made and no economic assessment has been undertaken.

Craig Ransley, Executive Chair of Amigo Resources PLC, commented:

"The consistency of the potassium across this block is unusual and it is the result we are most confident in. The rare earth and carbonate signatures are encouraging and clearly worth testing, but it is early and we intend to prove it properly before we claim anything more. The next programme is designed to answer those questions at modest cost."

Technical team

Field investigation at Musensi Hill was carried out by geologists of Geovale Services Private Limited including Mr Aishik Saha, under the direction of Dr Joy Gopal Ghosh, Principal Advisor to Geovale Services. Petrographic studies were carried out by Dr Joy Gopal Ghosh and Dr Tapan Chandra Pal, both formerly Deputy Directors General of the Geological Survey of India, with specialist experience in the petrology and geochemistry of alkaline igneous systems. Dr Ghosh and Dr Pal are named in acknowledgement of their contribution to the geological and petrographic interpretation; they are not Competent Persons for the purposes of this announcement. The Competent Person named above has reviewed their work and takes responsibility for the Exploration Results as reported.

Appendix - JORC Code (2012) Table 1

Sampling Techniques and Data

This appendix accompanies and forms part of the announcement High-grade potassium and associated rare earth enrichment confirmed by first-pass surface sampling at the Musensi Hill block, south-west Tanzania. Criteria are addressed on an "if not, why not" basis.

Criteria	JORC Code criterion (abridged)	Commentary
Sampling techniques	Nature and quality of sampling; measures taken to ensure sample representivity.	Surface rock chip grab samples collected from outcrop and subcrop across the Musensi Hill block (PL 12668/2024). Sixty samples were submitted for analysis, comprising 56 field localities and four quality-control inserts. Sampling targeted the full range of lithologies present - phonolite leucitite, associated volcaniclastic units, carbonate-veined rock and the surrounding gneissic basement. Grab sampling is a reconnaissance technique. Samples are selective, are not collected across a measured width, and are not representative of average grade, width or continuity. No channel, chip-line or panel sampling was undertaken. Rock samples generally comprised approximately 2-3 kg of material. Where possible, samples were collected as composites of multiple representative chips taken across the exposed lithological or mineralised unit rather than as isolated single pieces.
Drilling techniques	Drill type, diameter, orientation, core handling.	Not applicable. No drilling has been undertaken on the block. All results reported are from surface sampling.
Drill sample recovery	Recovery measurement and grade-bias assessment.	Not applicable. No drilling has been undertaken.
Logging	Whether samples have been logged to a level of detail supporting the reporting; qualitative or quantitative; extent of logging.	Each locality was logged in the field for lithology, veining, alteration and weathering by geologists of Geovale Services Private Limited under the direction of Dr Joy Gopal Ghosh. Fourteen representative samples were prepared as thin sections and logged petrographically by Dr Joy Gopal Ghosh and Dr Tapan Chandra Pal. Logging is qualitative for lithology, veining and alteration, and quantitative only were supported by the petrographic and assay data. Field lithological names were assigned at the time of collection and are retained in the database; several of these field names - in particular the use of "carbonatite" for carbonate-veined rock - are provisional and are superseded by the petrographic and geochemical classification. All 56 localities were logged. No photography or core logging applies.
Sub-sampling techniques and sample preparation	Whether sampling is appropriate to the grain size; nature of sub-sampling and preparation; quality control on sub-sampling.	Samples were submitted as whole rock chips to Shiva Analyticals (India) Private Limited. Crushing, splitting and pulverising were carried out by the laboratory under its documented internal procedures. No field splitting or field compositing was undertaken. Samples were initially crushed to approximately 70% passing 2 mm, after which a representative split was pulverised to achieve at least 85% passing 75 µm (-200 mesh). The pulverised material was homogenised, and the prescribed pulp aliquot was taken for digestion and instrumental analysis. Two field duplicates were submitted (sample numbers suffixed A), representing 3.6% of the 56 primary localities. Duplicate performance is reported under Quality of assay data below. Samples bearing an "A" suffix represent duplicate splits derived from the same original field sample rather than independently collected field duplicates. Accordingly, variation between paired results primarily reflects sample preparation, splitting and analytical variability and should not be interpreted as a direct measure of field sampling variability. The reproducibility of the major oxides (see below) indicates that the sample mass and preparation are adequate to the grain size for the major-element determinations. The greater variance observed in the trace elements indicates that they are not, for coarse or heterogeneously distributed accessory phases.
Quality of assay data and laboratory tests	Nature, quality and appropriateness of the assaying procedure; whether the technique is total or partial; nature of quality-control procedures and whether acceptable levels of accuracy and precision have been established.	All analyses were carried out by Shiva Analyticals (India) Private Limited, an independent commercial laboratory, and reported under certificate G6328. Sixty-seven analytes were determined per sample by the following documented methods: ● Major oxides (SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, Na₂O, K₂O, TiO₂, MnO, P₂O₅, SO₃, Cr₂O₃, V₂O₅) - SOP/OM/105, limits of quantification 0.05-0.08%. ● Loss on ignition - SOP/OM/103, LOQ 0.10%. ● Forms of carbon (total, carbonate and non-carbonate carbon) - SOP/OM/117, LOQ 0.01%. ● Cu, Ni, Pb, Sr, Zn, Zr - SOP/OM/051, LOQ 5 ppm. ● Rare earth elements and multi-element suite, including Nb, Ta, Hf, Th, U, Rb and the full lanthanide series - SOP/OM/052, LOQ 0.5-5 ppm. ● Ag, As, Ba, Hg - SOP/OM/059, LOQ 1-5 ppm. The methods are appropriate to the determination of major and trace element concentrations in silicate rocks. Samples analysed under SOP/OM/051 and SOP/OM/052 were subjected to four-acid digestion prior to instrumental analysis. The method is considered near-total for most common rock-forming and sulphide minerals; however, complete decomposition of highly refractory minerals such as zircon may not be achieved. Consequently, Zr and Hf, and potentially some REE hosted within refractory mineral phases, may be partially under-reported. Quality control - field duplicates. Two duplicate pairs were submitted. Major oxides reproduce closely: K₂O within 3.8% and 1.2% relative difference, Al₂O₃ within 1.8% and 1.6%, SiO₂ within 3.2% and 0.9%. Across 28 analytes compared, median relative difference is 11.7% and 13.9% respectively. Trace elements reproduce less well: Nb 24% and 27%, Ta 32% and 55%, Ba 54% and 8%, MnO 120% in one pair. Total rare earth oxide reproduced to 0.7% in the first pair and 15.8% in the second. The Competent Person's conclusion is that the potassium and major-oxide data, on which the principal result of this announcement rests, are repeatable to a level appropriate for reporting Exploration Results, while the trace-element and rare-earth data carry materially greater variance consistent with coarse-grained or heterogeneously distributed accessory phases. Individual trace-element and rare-earth values should be read as indicative rather than precise. Quality control - blanks. Two blank samples were submitted (sample numbers suffixed B). The two returned near-identical results - TREO 0.0376% and 0.0376%, Ce 156.0 and 155.7 ppm, TiO₂ 1.39% and 1.39%, SiO₂ 77.22% and 77.86% - demonstrating homogeneity of the blank material and reproducibility at the laboratory. Blank K₂O of 1.27% and 1.26% is approximately 9% of the median K₂O of the alkaline suite, indicating no material carry-over contamination affecting the potassium result. The blank material is a barren quartz-rich rock rather than a certified blank and carries an inherent rare earth content of 0.038% TREO, approximately 32% of the median TREO of the alkaline suite. It therefore constrains gross contamination only and cannot demonstrate the absence of low-level rare earth carry-over. Niobium differed between the two blanks (12.1 and 32.5 ppm); this is the only quality-control result falling outside acceptable limits and is to be investigated in the next programme. Quality control - certified reference materials. No certified reference materials were submitted with this batch. Analytical precision and freedom from gross contamination have therefore been tested, but analytical accuracy has not been independently verified and no statement on analytical bias can be made. Matrix-matched certified reference materials will be inserted at a rate of not less than one in twenty in the programme described under Next Steps. Internal consistency. Major-oxide totals including loss on ignition close between 99.4% and 99.9% for all alkaline-suite samples, which is consistent with complete and internally coherent major-element determinations. Total quality-control insertion rate for the batch was 4 in 60 submissions (6.7%), comprising 3.6% duplicates and 3.6% blanks relative to the 56 primary localities. This is below the one-in-twenty per control type that the Competent Person regards as standard practice, and is disclosed on that basis.
Verification of sampling and assaying	Verification of significant intersections; use of twinned holes; documentation of primary data; discussion of any adjustment to assay data.	The assay data used in this announcement were extracted directly from the digital text layer of laboratory certificate G6328 by script and reconciled value by value against the certificate. An earlier manual transcription of the same certificate was found to contain errors at a rate of approximately 9.7%, concentrated in the heavy rare earth elements; that transcription was discarded in full and is not the basis of any figure reported here. No adjustment, recalculation or top-cutting has been applied to any reported assay value. Derived quantities - total rare earth oxide, carbonate content and normative parameters - are calculated from the reported values using standard published conversion factors, and the close of major-oxide totals at 99.4-99.9% is the principal independent check on the dataset. No twinned samples exist and no independent verification of results by a second laboratory or by an alternative company has been undertaken. Primary geological and sampling data were recorded in field notebooks and standard field logging sheets and subsequently entered into the project digital database. Data entry was cross-checked by a second geologist against the original field records for completeness and transcription errors. Original field notebooks, sampling sheets and related records are retained in the head quarter.
Location of data points	Accuracy and quality of surveys used to locate samples; specification of the grid system; quality and adequacy of topographic control.	Sample locations, geological observation points and other field locations were recorded using a handheld GPS in WGS 84 datum. The positional accuracy indicated by the GPS and reported by the field operator during data acquisition was generally within approximately ±3-5 m. The four quality-control inserts carry the coordinates of their parent localities, giving 56 unique positions for 60 analyses. No topographic survey control has been established over the block and elevations are not reported. Positional accuracy is adequate for reconnaissance surface geochemistry and would require upgrading by surveyed control before any drilling or resource estimation.
Data spacing and distribution	Data spacing for reporting Exploration Results; whether spacing and distribution is sufficient to establish geological and grade continuity; whether sample compositing has been applied.	Fifty-six sample localities are distributed over a ground extent of approximately 2.2 km by 4.1 km within the 11 km² licence area, and across a mapped phonolite leucitite of approximately 3 km². Sampling was traverse- and exposure-controlled rather than laid out on a regular grid, and spacing is irregular. The distribution of samples is itself elongate, on an azimuth of approximately 166° with an elongation ratio of 2.3 to 1. This is a property of where sampling was possible and is disclosed because it bears on the apparent shape of every anomaly derived from the dataset. The spacing and distribution are appropriate to first-pass reconnaissance and are expressly not sufficient to establish geological or grade continuity for the purposes of Mineral Resource estimation. No sample compositing has been applied.
Orientation of data in relation to geological structure	Whether the orientation of sampling achieves unbiased sampling of possible structures; whether a sampling bias has been introduced.	Sampling was of surface exposures and was not oriented with respect to any structure. The phonolite leucitite is interpreted as a flat-lying to gently disposed sequence of extrusive flows; surface grab samples of it are therefore not subject to a systematic orientation bias, and the potassium result is not considered to be orientation-biased. The later carbonate veins are discrete and steeply disposed. Grab samples of vein material are selective and are biased towards visibly veined and mineralised rock. No relationship between sampling orientation and true vein width has been established, and no true width is reported. An apparent 172° corridor in the distribution of carbonate-bearing samples, reported in earlier internal work on this block, has since been tested and found to be indistinguishable from the orientation of the sampling itself. The azimuth is unstable to the removal of individual samples, moving to 149° and 109° on removal of the two and four most distant points. No structural control on the carbonate is claimed in this announcement.
Sample security	The measures taken to ensure sample security.	Samples were collected by the project geologists, placed in individually labelled sample bags and assigned unique sequential sample identification numbers. Sample bags were sealed in the field and grouped into larger buckets, which were securely closed prior to dispatch. The samples remained under the custody of project personnel until transfer to the transport provider and subsequent delivery to the laboratory. On receipt, the laboratory checked the sample numbers against the submitted sample dispatch sheet and inspected the packages for damage or evidence of tampering. Samples were submitted to Shiva Analyticals (India) Private Limited, an independent commercial laboratory with no interest in the project. Field duplicates and blank samples were inserted into the sample sequence using unique sample identification numbers consistent with the routine sample numbering system. The laboratory was therefore not able to identify these samples as QA/QC controls from the sample numbers, and they were submitted blind as part of the routine analytical batch.
Audits or reviews	The results of any audits or reviews of sampling techniques and data.	The assay dataset, its derived parameters and the geological interpretation have been reviewed by the Competent Person. That review included independent re-extraction of the primary assay data from the laboratory certificate, recalculation of all derived values, and testing of the spatial and statistical claims made in earlier internal work - as a result of which three interpretive claims were withdrawn before this announcement was prepared. Petrographic interpretation has been reviewed by Dr Joy Gopal Ghosh and Dr Tapan Chandra Pal. No external audit of field sampling procedures, of sample security or of the database has been undertaken.

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