REG - Andrada Mining Ltd - Mineral Resource Update at Uis
06/02/2025 07:15
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RNS Number : 1616W Andrada Mining Limited 06 February 2025
THE INFORMATION CONTAINED WITHIN THIS ANNOUNCEMENT IS DEEMED BY THE COMPANY TO
CONSTITUTE INSIDE INFORMATION AS STIPULATED UNDER THE MARKET ABUSE REGULATIONS
(EU) NO. 596/2014 (MAR) AS IN FORCE IN THE UNITED KINGDOM PURSUANT TO THE
EUROPEAN UNION (WITHDRAWAL) ACT 2018. UPON THE PUBLICATION OF THIS
ANNOUNCEMENT VIA REGULATORY INFORMATION SERVICE (RIS), THIS INSIDE INFORMATION
WILL BE IN THE PUBLIC DOMAIN.
Andrada Mining Limited
("Andrada" or "the Company")
Updated Mineral Resource Estimate for the Uis tin mine V1V2 pegmatite
Andrada Mining Limited (AIM: ATM, OTCQB: ATMTF), a critical raw materials
producer with mining and exploration assets in Namibia, announces an updated
Mineral Resource Estimate ("MRE") for the V1V2 pegmatite at the Uis tin mine.
This is an update on the MRE announced on 6 February 2023¹, and incorporates
analytical results from the final 16 drill holes of the 2022 drilling
programme, as well as a volume depletion surface as at 30 August 2024.
HIGHLIGHTS
§ Increases in average lithium grade and volumes of the measured and
indicated resource classifications
§ Average lithium grade increases to 0.79% Li(2)O from 0.73% Li(2)O declared
in 2023¹
− Contained lithium oxide ("Li(2)O") increases from 587 000 tonnes to
610 000 tonnes
§ Measured resource tonnage increases by 30% to c27.3 million tonnes ("mt")
§ Indicated resource tonnage increases by 2% to c17.5mt
§ MRE total tonnage decreases from 81mt in 2023 to 77.5mt due to depletion
from on-going mining
Anthony Viljoen, Chief Executive Officer, commented:
"This updated resource estimate is another positive step toward our goal of
being a premiere African producer of tin, lithium and tantalum. Our
exploration team has once again demonstrated that the V1V2 pegmatite has
significant lithium potential, shown by increases in both the average lithium
grade and contained metal tonnage. Critically, this updated resource also
allows us to better quantify the potential lithium concentrate credits we can
generate alongside our tin production, optimising the overall project
economics. Furthermore, the updated MRE further enhances the project
economics of the Uis mine operations and will enable the determination of a
lithium mineral reserve.
RESULTS Overview
The MRE has been informed by 145 historical ISCOR drillholes comprising eight
(8) Diamond Drillholes ("DD") and one hundred and thirty-seven (137) Reverse
Circulation ("RC") drillholes, together with seventy-seven (77) validation
drill holes, comprising forty-eight (48) DD and twenty-nine (29) RC drillholes
drilled by Andrada between 2018 and 2023. The Andrada drillholes were
completed on a nominal grid spacing of 60m by 60m, with wider spacing of up to
80m by 200m for the deeper portions. Most holes were drilled at a vertical
orientation, but selected shallower holes were inclined at angles up to -70°
southeast, to obtain intersections more perpendicular to the dipping
pegmatite. The locations of all V1V2 drillhole collars are shown in Figure 1.
The 2023 MRE¹ update was determined from geological information of all holes
above, except for 16 holes (V1V2034, 35, 37, 38, 40, 43, 44, 48, 50, 51, 52,
53, 54, 58, 63 and 80) whose data were not available at the date of
publication. The current MRE update includes analytical data from the final 16
drillholes obtained subsequent to the previously published MREs (see
announcements dated 2 February 2023² and 30 March 2023³).
¹ https://polaris.brighterir.com/public/andrada_mining/news/rns/story/x4g8q3x
(https://polaris.brighterir.com/public/andrada_mining/news/rns/story/x4g8q3x)
² https://polaris.brighterir.com/public/andrada_mining/news/rns/story/x8en45x
(https://polaris.brighterir.com/public/andrada_mining/news/rns/story/x8en45x)
³ https://polaris.brighterir.com/public/andrada_mining/news/rns/story/xoo1nmx
(https://polaris.brighterir.com/public/andrada_mining/news/rns/story/xoo1nmx)
Figure 1: Image indicating the location and name of the drill holes from the
2022 programme.
The updated V1V2 MRE is reported in accordance with the JORC Code (2012) and
identifies 77.51 Mt of mineralised pegmatite with an average grade of 0.79 %
Li(2)O, 0.15 % Sn and 82 ppm Ta. This MRE includes 27.33 mt at an average
grade of 0.82 % Li(2)O, 0.15 % Sn and 90 ppm Ta for the near surface Measured
category, 17.50 mt at an average grade of 0.79 % Li(2)O, 0.15 % Sn and 86 ppm
Ta for the Indicated category, and 32.68 mt with an average grade of 0.76 %
Li(2)O, 0.16 % Sn and 73 ppm Ta for the Inferred category. The contained
lithium is also stated in terms of Lithium Carbonate Equivalent, being the
metal converted to lithium carbonate by a factor of 5.323.
The MRE is reported within a conceptual pit shell to demonstrate reasonable
prospects for eventual economic extraction ("RPEEE") and incorporates the sale
of petalite and cassiterite. Rubidium (Rb - in mica), tantalite and niobium
associated with Ta in the columbite group minerals (CGM)) concentrations and
tonnages were also estimated but have not been included in the RPEEE
considerations.
The MRE is reported on a gross basis in Table 1. An attributed-basis
tabulation of resources, as presented in previous estimates, is no longer
applicable because the V1V2 pegmatite is within the Uis mining license (ML
134) now wholly owned by Andrada Mining and its subsidiaries (see announcement
dated 27 June 2024). Proportional changes in the tonnages and grade between
the 2023 MRE and the current MRE are presented in Table 2.
Table 1: V1 and V2 deposit MRE in accordance with JORC (2012)
Classification Tonnes (mt) Grades
Sn Li Li(2)O Rb Ta Nb
(%) (ppm) (%) (ppm) (ppm) (ppm)
Measured 27.33 0.15 3 814 0.82 1 435 90 117
Indicated 17.50 0.15 3 656 0.79 1 370 86 115
Measured and indicated 44.83 0.15 3 753 0.81 1 410 89 116
Inferred 32.68 0.16 3 520 0.76 1 279 73 110
Total 77.51 0.15 3 655 0.79 1 355 82 114
Classification Contained metal (kt)
Sn Li Li(2)O LCE* Rb Ta Nb
Measured 40.0 104.2 224.4 554.5 39.2 2.5 3.2
Indicated 26.5 64.0 137.8 340.4 24.0 1.5 2.0
Measured and indicated 66.5 168.2 362.2 895.1 63.2 4.0 5.2
Inferred 51.6 115.0 247.7 611.9 41.8 2.4 3.6
Total 118.0 283.3 610.0 1 507.0 105.0 6.4 8.8
Source: ERM, 2025
Note: The constraining pit shell is based on a tin price of USD 25 500/t and a
price of USD 1 500/t for a 4% Li(2)O petalite concentrate. Losses and mining
dilution were set at 5%. Pit slope angles were assumed to be 55°. An assumed
metallurgical recovery of 80% was used for Sn producing a concentrate with Sn
metal content of 60%, and Li(2)O (as petalite) recovery of 45%. The mining,
treatment, G&A and selling costs have been supplied by Andrada and
reviewed for reasonableness by ERM. Tabulated data has been rounded off which
may result in minor computational errors.
* The contained lithium is also stated in terms of Lithium Carbonate
Equivalent being the metal converted to lithium carbonate by a factor of 5.323
(i.e. LCE = Li x 5.323).
The operator is Andrada being the 100% owner of the Uis mining licence
(ML134).
Table 2: Percentage change of tonnes contained, grades and deposit size.
MRE Year Tonnes (Mt) Sn % Contained Sn metal (t) Li(2)O % Contained Li(2)O (t) Ta ppm Contained Ta metal (t)
2023 81 0.15 120 000 0.73 587 000 86 6 960
2025 77.51 0.15 118 000 0.79 610 000 82 6 400
% Change -4% 0% -2% 8% 4% -5% -8%
This MRE update provides an increase of the lithium grade and tonnage in the
Measured and Indicated classification. These results further outline the
polymetallic potential of the V1V2 pegmatite. The surface information used for
the basis of this MRE was acquired at the end of August 2024, and the volumes
mined since the previous MRE¹ have been accounted for, resulting in a reduced
overall tonnage.
Geology and geological interpretation
The V1V2 deposit is hosted within rocks formed during the Damara Orogen, a
typical Pan-African orogenic belt, which formed between 750 Ma and 440 Ma
during the assembly of Gondwana. The orogenesis resulted in the production of
voluminous quantities of granitic magma during the syntectonic phases of
collision. This was followed by a pegmatitic phase of magmatism in the
post-tectonic environment, populating the Damara Orogen with numerous
pegmatitic intrusions.
The V1V2 pegmatite has a sigmoidal shape in plan and is hosted in biotite
schists and a distinctive cordierite (with biotite and quartz replacement of
cordierite)-bearing knotted schist (the so-called "knottenschiefer"). The
pegmatite strikes to the northeast and dips to the northwest at angles of
between 30° and 50°. The tin and lithium mineralisation is primarily
magmatic with some tin mineralisation associated with a late-stage mica-rich
greisen phase. The primary lithium mineral identified within the pegmatite is
petalite.
Modelling and estimation
An in-situ Mineral Resource Estimate (MRE) was undertaken for the pegmatite
bodies. Mineralisation wireframes were guided entirely by geology and resulted
in the generation of three-dimensional (3D) geological models of the V1 and V2
pegmatites that merge at depth to form the V1V2 pegmatite body. The pegmatite
wireframes were also used to define the mineralisation envelopes. Internal
waste was represented by the xenolith wireframes. The August 2024 monthly
photogrammetric survey at Uis was used to generate a high-resolution
topographic surface that was subsequently used to constrain the resource.
A block model, constrained by the interpreted mineralised envelopes and
topographic surfaces, was constructed. A parent cell size of 20 m(E) x 20 m(N)
x 10 m(RL) was adopted with standard sub-celling to 2 m(E) x 2 m(N) x 1 m(RL)
to maintain the resolution of the mineralised lenses. The samples were
composited to 2m lengths. A small number of tin samples were considered
grade outliers, and a top-cut of 1.0% for Sn applied to the dataset (only Sn
grades were top-cut). These composites were the basis for the estimation of
all Sn, Li, Nb, Rb and Ta grades into the block model using Ordinary Kriging
(OK) interpolation, with the V1 and V2 pegmatites treated as separate domains.
The block grades were validated both visually and statistically against
composite grades. A mean dry bulk density value of 2.65 was assigned to all
pegmatite material. Cross sections through the resulting block model, provide
an indication of the typical grade profiles for Sn, Li and Ta respectively, as
presented in Figure 2,Figure 3, and Figure 4. No significant statistical
correlation between the various metals was identified from the data, resulting
in each metal being estimated independently.
Figure 2: Typical cross section of the Block model and Input Composite data
coloured by Sn Grade, looking northeast. Source: ERM, 2025
Figure 3: Typical cross section of the Block model and Input Composite data
coloured by Li Grade, looking northeast. Source: ERM, 2025
Figure 4: Typical cross section of the Block model and Input Composite data
coloured by Ta Grade, looking northeast. Source: ERM, 2025
Mineral resource classification criteria
The Mineral Resource has been classified into Measured, Indicated and Inferred
categories in accordance with guidelines specified within the JORC Code 2012
Edition. The classification level is based upon an assessment of the
geological understanding of the deposit, geological and grade continuity,
drillhole spacing, quality control results, search and interpolation
parameters, and an analysis of available density information.
Geostatistically, confidence classifications were assigned based on the slope
of regression (SoR) metrics per block for Sn, being the lowest confidence
analyte overall to be estimated. A SoR value of > 0.8 was used to classify
blocks as Measured and a SoR > 0.55 was to classify blocks as Indicated.
All other Mineral Resources not already classified and constrained to blocks
with a SOR of > 0.25 and not more than 50 m from at least four samples,
were classified as Inferred. It was found that Measured and Indicated Mineral
Resources were interspersed, so that wireframe boundaries between the two
categories were imposed, as guided by the SoR and distances from informing
samples. These wireframes defined coherent zones for each classification
assignment.
Figure 5: Plan View of the MRE Block Model, Coloured by CLASS (Red = Measured,
Green = Indicated, Blue = Inferred), with drillhole collars displayed coloured
by drill phase. Source: ERM, 2025
Competent Person statement
The technical data relating to the Mineral Resources in this announcement have
been reviewed by Anthony Wesson who was an employee of ERM Ltd when the work
was undertaken and is a Fellow of the Australasian Institute of Mining and
Metallurgy. Anthony Wesson has sufficient experience relevant to the style of
mineralisation and type of deposit under consideration and to the activity
which he is undertaking to qualify as Competent Persons as defined in the 2012
Edition of the Australasian Code for the Reporting of Exploration Results,
Mineral Resources, and Ore Reserves (JORC Code). Anthony Wesson consents to
the disclosure of information in this report in the form and context in which
it appears.
The technical data relating to the exploration results in this announcement
have been reviewed by Michael Cronwright an employee of ERM UK Ltd, a Fellow
of the Geological Society of South Africa and a Professional Registered
Natural Scientist (Geology) with the South African Council of Natural
Scientific Professions. He has sufficient experience 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
2012 Edition of the Australasian Code for the Reporting of Exploration
Results, Mineral Resources, and Ore Reserves (JORC Code). Mr Cronwright
consents to the inclusion of the information in the form and context in which
it appears.
Glossary of abbreviations
CGM Columbite Group Minerals. This includes tantalite (Ta(2)O(5)) and columbite
(Nb(2)O(5)) that host Ta and Nb mineralisation in pegmatite deposits.
DD Diamond core drilling
LCE Lithium Carbonate Equivalent.
Li Symbol for Lithium
Li → Li(2)O Metal to metal-oxide conversion factor of 2.153
Li → LCE Metal to lithium carbonate equivalent conversion factor of 5.323
Li(2)O Lithium oxide
JORC The Australasian Code for Reporting of Exploration Results, Mineral Resources
and Ore Reserves
KE Kriging Efficiency
MRE Mineral Resource Estimate
Nb Symbol for Niobium
PPM Parts Per Million
QA/QC Quality Assurance / Quality Control
Rb Symbol for Rubidium
RC Reverse Circulation drilling
RPEEE Reasonable Prospects for Eventual Economic Extraction
SG Specific Gravity
Sn Symbol for Tin
SoR Slope of Regression
Ta Symbol for Tantalum
V1V2 Name of the targeted pegmatite unit, V1V2 denotes where the V1 and V2
pegmatites have merged at depth.
Glossary of technical terminology
Apparent thickness The relationship between apparent width and true thickness is based on the
formula by Addie (1968 Economic Geology, vol 63, pp 188-189).
Dip angle The angle of inclination measured downward from horizontal.
Geological model The interpretation of mineralisation and geology that controls
mineralisation. This is usually generated in a three-dimensional computer
environment.
Indicated Mineral Resource The part of a Mineral Resource for which quantity, grade, quality, etc., can
be estimated with a level of confidence sufficient to allow the appropriate
application of technical and economic parameters, to support mine planning and
evaluation of economic viability
Inferred Mineral Resource The part of a Mineral Resource for which quantity and grade or quality can be
estimated on the basis of geological evidence and limited sampling and
reasonably assumed, but not verified, geological and grade continuity
Measured Mineral Resource The part of a Mineral Resource for which quantity, grade or quality, etc., are
well enough established that they can be estimated with confidence sufficient
to allow the appropriate application of technical parameters to support
production planning and evaluation of economic viability
Mineral resources Mineral Resources are sub-divided, in order of increasing geological
confidence, into Inferred, Indicated and Measured categories. An Indicated
Mineral Resource has a higher level of confidence than an Inferred Mineral
Resource but has a lower level of confidence than a Measured Mineral Resource.
Pegmatite An igneous rock typically of granitic composition, which is distinguished from
other igneous rocks by the extremely coarse and systematically variable size
of its crystals, or by an abundance of crystals with skeletal, graphic, or
other strongly directional growth habits, or by a prominent spatial zonation
of mineral assemblages, including monomineralic zones.
Petalite Lithium bearing aluminosilicate (LiAlSi(4)O(10)) with a maximum theoretical Li
content of 4.5%. Current applications largely in the glass and ceramic
industry but can potentially be used in the battery chemical market employing
similar processes and technologies used to process spodumene.
Xenolith A foreign rock fragment (e.g., schist) within an intrusive body (e.g.
pegmatite) that is unrelated to the igneous body.
CONTACTS +27 (11) 268 6555
Andrada Mining
Anthony Viljoen, CEO
Sakhile Ndlovu, Investor Relations
NOMINATED ADVISOR & BROKER
Zeus Capital Limited +44 (0) 20 2382 9500
Katy Mitchell
Harry Ansell
Andrew de Andrade
CORPORATE BROKER & ADVISOR
H&P Advisory Limited +44 (0) 20 7907 8500
Andrew Chubb
Jay Ashfield
Matt Hasson
Berenberg +44 (0) 20 3753 3040
Jennifer Lee
Natasha Ninkov
FINANCIAL PUBLIC RELATIONS
Tavistock (United Kingdom) +44 (0) 207 920 3150
Emily Moss
andrada@tavistock.co.uk (mailto:andrada@tavistock.co.uk)
Josephine Clerkin
About Andrada Mining Limited
Andrada Mining Limited is listed on the London Stock Exchange (AIM), New York
(OTCQB) and Namibia Stock Exchange with mining assets in Namibia, a top-tier
investment jurisdiction in Africa. Andrada strives to produce critical raw
materials from a large resource portfolio to contribute to a more sustainable
future, improved living conditions and the upliftment of communities adjacent
to its operations. Leveraging its strong foundation in Namibia, Andrada is on
a strategic path to becoming a leading African producer of critical metals
including lithium, tin, tungsten, tantalum and copper. These metals are
important enablers of the green energy transition, being essential for
components of electric vehicles, solar panels and wind turbines.
APPENDIX A JORC TABLE (2012 EDITION), TABLE 1
Section 1: Sampling Techniques and Data
Criteria JORC Code explanation Commentary
Sampling techniques Nature and quality of sampling (e.g. cut channels, random chips, or specific ISCOR
specialised industry standard measurement tools appropriate to the minerals
under investigation, such as downhole gamma sondes, or handheld XRF Historical drilling completed by ISCOR (Iron and Steel Corporation (Pty) Ltd)
instruments, etc.). These examples should not be taken as limiting the broad was used and in the exploration database and comprised 13 diamond (DD)
meaning of sampling. drillholes and 138 percussion holes with 1 m sampling intervals, within the V1
and V2 pegmatite area. Although there are no reports discussing details of the
Include reference to measures taken to ensure sample representivity and the sampling protocols, there is evidence that investigations into sample
appropriate calibration of any measurement tools or systems used. reproducibility and repeatability were carried out and the nuggety nature of
the tin mineralisation was recognised. Despite this local variability, the
Aspects of the determination of mineralisation that are Material to the Public average grade of tin appeared to be consistent around 0.14% Sn, similar to
Report. In cases where 'industry standard' work has been done this would be what has been estimated in this MRE. Andrada
relatively simple (e.g. 'reverse circulation drilling was used to obtain 1 m
samples from which 3 kg was pulverised to produce a 30 g charge for fire 2018 to 2019
assay'). In other cases, more explanation may be required, such as where there
is coarse gold that has inherent sampling problems. 26 diamond (DD) drillholes totalling 4,434.7 m were drilled by Andrada Mining
Limited (Andrada). Assay results for the deep holes (21 to 26) were not
Unusual commodities or mineralisation types (e.g. available at the time of reporting but geological logging from these holes
were used to constrain the geological modelling. Assay results from holes 1 to
submarine nodules) may warrant disclosure of detailed information 20 have been reported.
Sample intervals were determined by the geologist, where possible samples were
taken in 1 m intervals at the start of each metre mark. In areas where
lithological contacts were present (xenoliths included), the sample was taken
from the nearest metre mark to the contact.
Drill core was either sampled as full core (all core taken for sample) or cut
in half using a core cutter, then sampled as half core with the other half
remaining in the core tray. Approximately 33% of the core was sampled as full
core.
All samples were crushed to a <1 mm grain size before being split by rotary
splitter, where required, duplicate samples were also split during this stage.
A 150 g sample was split from each core sample and for further processing and
analysis.
The remainder of the sample was re-bagged with an original sample ticket and
marked as coarse reject. These samples have been placed in secure storage.
2022
22 DD drillholes totalling 3,286.02 m and 29 reverse circulation (RC) holes
totalling 4,332 m were drilled by Andrada. Assay results for the deep holes
(V1V2021 to 026) were not available at the time of reporting but geological
logging from these holes were used to constrain the geological modelling.
Assay results from these holes have since been reported and included in
subsequent updates.
Criteria JORC Code explanation Commentary
For the DD holes, the sample intervals were determined by the geologist, where
possible samples were taken in 1 m intervals at the start of each metre mark.
In areas where lithological contacts were present (xenoliths included), the
sample was taken from the nearest metre mark to the contact.
Drill core was cut in half using a core cutter, then sampled as half core with
the other half remaining in the core tray.
The RC drilling produced bags of pulverised rock material at 1 m intervals
weighing approximately 30 kg on average. These 1 m bulk percussion samples
were split 50%:50% using an RSE Projects rotary splitter down to produce ~15
kg subsamples. Field duplicates were prepared from the remaining discarded
material.
All samples were crushed to a <1 mm grain size before being split by rotary
splitter to produce a 500 g aliquot, where required, duplicate samples were
also split during this stage.
The 500 g aliquots were split and combined (homogenised) using a rotary
splitter to separate the 150 g sample which was further processed for
analysis. Each 150 g sample was then further milled until 97% of the sample
passed through a 0.075 mm sieve. A 2 g aliquot was taken from the pulverised
material for digestion and assay.
The remainder of the sample was re-bagged with an original sample ticket and
marked as coarse reject. These samples have been placed in secure storage.
Drilling techniques Drill type (e.g. core, reverse circulation, open-hole hammer, rotary air ISCOR
blast, auger, Bangka, sonic, etc.) and details (e.g. core diameter, triple or
standard tube, depth of diamond tails, face-sampling bit or other type, Available archive material sets out that an Atlas Copco ROC61 percussion rig,
whether core is oriented and if so, by what method, etc.). with a 115 mm hammer, was the predominant rig type used for the percussion
drilling. Samples were collected on a 1 m basis. No information is available
for the diamond drilling undertaken by ISCOR.
Andrada
2018 to 2019
For the 2018-2019 DD drilling campaign, all samples were obtained through DD
drilling, primarily at PQ size, utilising standard 1.5 m or 3.0 m core
barrels.
Majority of the drilling was vertically orientated with some of the shallower
drillholes were inclined, up to 70°, to intersect closer to a true thickness.
2022
For the 2022 drilling, a combination of HQ diameter diamond drilling,
utilising standard 1.5 m or 3.0 m core barrels and 137 mm diameter RC
drilling.
Majority of the drilling was vertically orientated with some of the shallower
drillholes were inclined, up to 70°, to intersect closer to a true thickness.
Criteria JORC Code explanation Commentary
Drill sample recovery Method of recording and assessing core and chip sample recoveries and results ISCOR
assessed.
No recovery information was available.
Measures taken to maximise sample recovery and ensure representative nature of
the samples. Andrada
Whether a relationship exists between sample recovery and grade and whether 2018 to 2019
sample bias may have occurred due to preferential loss/gain of fine/coarse
material. Core recovery is calculated as the length of recovered core over the driller
length or each recovered drill run.
Recoveries were good overall with small losses occurring in areas where the
schist has been fractured. Recoveries for pegmatite material were excellent
(>97%).
No special methods were used to aid core recovery in fractured areas. Sample
loss in these areas is not thought to be material as the pegmatite is the
primary mineralised lithology.
2022
Core recoveries for the DD holes was calculated as per previous drilling and
averaged 98%.
Recoveries for the RC drilling averaged ~77% through pegmatite intersections -
based on theoretical maximum recovery of specific gravity (SG) 2.65 material
and hole diameter of 137 mm. Sample masses averaged ~30 kg and ranged from 3.4
kg to 57.6 kg.
Logging Whether core and chip samples have been geologically and geotechnically logged ISCOR
to a level of detail to support appropriate Mineral Resource estimation,
mining studies and metallurgical studies. Simplified metre-based geological logs and accompanying tin assay data are
available for the ISCOR drilling and have been digitised by Andrada.
Andrada
2018 to 2019
Each core box was photographed five times. Once dry and four times on
different brightness and contrast settings while wet. All photographs were
taken under two oppositely spaced 5000 lumen spotlights.
The entire length of core was logged for all intersections. Geological logs
are all qualitative.
For each drillhole, both simple and detailed geological logs were created. The
following observations were defined in each log entry: alteration type and
intensity, mineral occurrences, mineralogical modal abundances, iron-manganese
and iron-oxide presence, a qualitative modal abundance of observed
tintantalum-niobium oxides, lithium-phases or sulphides, mineralogical
textures, weathering intensity, colour, grain size and grain size
distributions, contacts type (gradational or sharp) and any other geological
comment the geologist may have had. This was done for both host rocks and
pegmatites. Geotechnical logging was also carried out.
Downhole surveys were completed on all drillholes after completion and all
hole positions were surveyed using a differential global positioning system
(GPS).
Fractures, faults and veins within the core were also logged.
Criteria JORC Code explanation Commentary
2022
Each core box was photographed twice. Once dry and once while wet. All
photographs were taken under four 7700 lumen light which emit >95% of the
visible colour spectrum.
The entire length of core was logged for all intersections. Geological logs
are all qualitative.
For each drillhole, both simple and detailed geological logs were created. The
following observations were defined in each log entry: alteration type and
intensity, mineral occurrences, mineralogical modal abundances, iron-manganese
and iron-oxide presence, a qualitative modal abundance of observed
tintantalum-niobium oxides, identified lithium-phases or sulphides,
mineralogical textures, weathering intensity, colour, grain size and grain
size distributions, contacts type (gradational or sharp) and any other
geological comment the geologist may have had. This was done for both host
rocks and pegmatites. Geotechnical logging was also carried out.
Downhole surveys were completed on all drillholes after completion and all
hole positions were surveyed using a differential GPS.
Fractures, faults and veins within the core were also logged.
Subsampling techniques and sample preparation If core, whether cut or sawn and whether quarter, half or all core taken. ISCOR
If non-core, whether riffled, tube sampled, rotary split, etc. and whether No information about subsampling for the historical drilling was available.
sampled wet or dry.
Andrada
For all sample types, the nature, quality and appropriateness of the sample
preparation technique. 2018 to 2018
Quality control procedures adopted for all subsampling stages to maximise Approximately 33% of drillholes were sampled as full core, with the remainder
representivity of samples. sampled as half core.
Measures taken to ensure that the sampling is The full-core analysis was utilised to test the nugget effect and determine
potential bias associated with sample size. No bias was detected, and
representative of the in-situ material collected, including for instance half-core samples are considered reliable for their use in the MRE.
results for field duplicate/second-half sampling.
The sample size used is appropriate for the coarse-grained nature of the
Whether sample sizes are appropriate to the grain size of the material being pegmatite deposit as the largest diamond core drill size commercially
sampled. available was utilised for this program.
Where core was sampled as whole core, no cutting/splitting was involved. The
entire drilled sample was then sent for assay.
Half-core samples were cut in half using a diamond studded blade in a core
saw, a consistent side of the split core was sampled.
Samples were then transported to a controlled facility where they were further
processed.
Irrespective of the sample type; full or half core, each sample was crushed in
its entirety to <1 mm prior to sample splitting.
Samples were split and combined using a rotary splitter to separate the 150 g
sample which was further processed for analysis.
Each 150 g sample was then further milled until 97% of the sample passed
through a 0.075 mm sieve.
5% of all samples were split in duplicate to verify representativity.
Criteria JORC Code explanation Commentary
2022
All drill core (HQ diameter) was sampled as half core and is considered
appropriate for the coarsegrained nature of the pegmatite and associated
mineralisation.
The entire sample of RC drilling chips were collected from each 1m interval
weighing approximately 30 kg. These 1 m bulk percussion samples were split
50%:50% using an RSE Projects rotary splitter down to produce ~15 kg
subsamples.
All samples were crushed to a <1 mm grain size before being split by rotary
splitter to produce a 500 g aliquot, where required, duplicate samples were
also split during this stage.
The 500 g aliquots were split and combined (homogenised) using a rotary
splitter to separate the 150 g sample which was further processed for
analysis. Each 150 g sample was then further milled until 97% of the sample
passed through a 0.075 mm sieve. A 2 g aliquot was taken from the pulverised
material for digestion and assay.
5.8% of all samples were split in duplicate to verify representivity. Crush
duplicates (<1 mm material) were taken for the DD holes and a combination
of field duplicates (66%) and crush duplicates (33%) collected from the RC
holes duplicate samples.
Quality of assay data and laboratory tests The nature, quality and appropriateness of the assaying and laboratory ISCOR
procedures used and whether the technique is considered partial or total.
Historical assay work (tin only) was performed using an x-ray fluorescence
(XRF). No information regarding historical quality assurance/quality control
(QAQC) or laboratory testwork was available for historical samples.
Andrada
2018 to 2019
The primary assay laboratory (UIS Labs, Pretoria, South Africa) reported tin,
tantalum and niobium assays by lithium borate fusion with nitric acid
dissolution and ICP-MS (inductively coupled plasma-mass spectrometry) finish,
and lithium by multi-acid high pressure microwave digestion with ICP-MS
finish. These methods are considered total dissolution methods for the
elements listed and appropriate for the elements of interest
The umpire laboratory (ALS Chemex, Vancouver) used method ME-MS89L (sodium
peroxide fusion with an ICP-MS finish) to report all elements of interest -
this is considered an appropriate total dissolution technique for all reported
elements.
Two different certified reference material (CRM) standards were created from
bulk samples acquired from the deposit to ensure the CRMs were matrix
matched.
One CRM remained as it was processed to represent the average expected grade
of the deposit (AMIS 0629) the other CRM (AMIS 0631) was seeded with
additional cassiterite, sourced from artisanal processing within the Uis mine
area; this resulted in the certification of a higher grade standard to ensure
accuracy remains for samples above average.
Criteria JORC Code explanation Commentary
Standards comprised 5% of the assay data and were inserted at set intervals.
Blank samples were also inserted in a ratio of 20:1 so ensure clean lab
practices. In addition, the analytical laboratory inserted their own
duplicates and blanks.
A further 20% of the samples were transported to a second independent
laboratory for analysis as an additional verification process of the initial
results.
Acceptable levels of accuracy and precision have been achieved and the results
are considered acceptable for the estimation of Mineral Resources. Some
remedial work was undertaken to re-certify some of the custom-made CRMs
produced by Andrada and commercially certified by AMIS due to consistent high
bias issues noted at the primary laboratory (both as blind and known CRMs) and
the umpire laboratory which have been acknowledged by the CRM manufacturer.
This has since been resolved and all CRM certificates re-issued.
2022
The primary assay laboratory (UIS Labs, Pretoria, South Africa) reported tin,
tantalum and niobium assays by lithium borate fusion with nitric acid
dissolution and ICP-MS finish, and lithium by multi-acid high pressure
microwave digestion with ICP-MS finish. These methods are considered total
dissolution methods for the elements listed and appropriate for the elements
of interest.
The umpire laboratory (SGS, Johannesburg) used methods GE_ICP90A50 and
GE_IMS90A50 (sodium peroxide fusion with an ICP-MS finish) to report a
46-element suite including tin, tantalum and lithium - this is considered an
appropriate total dissolution technique for all reported elements.
Two different CRM standards were created from bulk samples acquired from the
deposit to ensure the CRMs were matrix matched representing the average
expected grade of the deposit (AMIS 0629) the other CRM (AMIS 0631) was seeded
with additional cassiterite as a higher grade tin standard to ensure accuracy
remains for samples above average.
Standards comprised 5% of the assay data and were inserted at set intervals.
Blank samples, comprising a silica pulp sourced from AMIS (AMIS 0577), were
also inserted in a ratio of 20:1 so ensure clean lab practices. In addition,
the analytical laboratory inserted their own duplicates and blanks.
A further 415 samples (11%) of the samples were transported to the second
independent laboratory (i.e. Intertek) for analysis as an additional
verification process of the initial results.
Verification of sampling and assaying The verification of significant intersections by either independent or Two site visits were conducted during the drill programmes completed to date
alternative company personnel. by the independent Competent Persons to verify the existence and intersections
of the drilled core. The first visit was conducted by Mr Wesson in October
2018 and the second by Mr Cronwright in June 2022.
Several holes drilled in 2018-2019 were closely spaced to historical data to
test intersections of the deposit spatially; however, due to the heterogeneity
of the tin mineralisation in the pegmatite intrusion, the twinned holes were
not expected to be identical in terms of mineralisation or petrology.
Mineralised widths in twinned holes were found to be consistent with the
original drillhole.
Criteria JORC Code explanation Commentary
No adjustments were made to the primary assay data. Andrada's in-house
database was used for data validation and storage and data was also validated
on import into Leapfrog which was used for the geological modelling.
No verification sampling was conducted during the 2022 drilling program.
Location of data points Accuracy and quality of surveys used to locate drillholes (collar and downhole ISCOR
surveys), trenches, mine workings and other locations used in Mineral Resource
estimation. Many of the historical collars have been identified in the field by Andrada
and surveyed using a differential GPS. These positions are consistent with
positions recorded in the ISCOR dataset providing confidence in the historical
data.
Andrada
All collar positions of drillholes were surveyed onto the ground by an
independent surveyor using a differential GPS (3 cm accuracy for X and Y and 8
cm accuracy for Z). The coordinate system used throughout was Universal
Transverse Mercator (UTM) 33S, WGS84.
Upon finalisation of the program, the drill collars were surveyed by the
surveyor employed by Andrada. In some areas, the collar location was slightly
altered due to access and safety concerns.
Downhole surveys were conducted using an EZTrak™ and accelerometer survey
tool. Multiple downhole surveys were taken for each hole and the tools
calibration standards were checked and up to date. Downhole readings were
taken every 9 m. The typical other data such as magnetic and gravitation
readings were also recorded for each station within the hole for the downhole
survey to do quality checks. For example, stations where magnetic readings
varied from the average across the hole by more than 200 nT were highlighted
and double checked. Readings were removed if data were found to be inaccurate
based on typical validation techniques utilised on downhole surveys.
WGS 1984 UTM 33S was used for the project coordinate system for collar
positions and grids.
Drone stereopairs, with a 6.6 cm image resolution and are georeferenced using
18 ground control points, to create digital elevation models of the
exploration area for a highly accurate control on the topography
Data spacing and distribution Data spacing for reporting of Exploration Results. The 2019 drilling program proposed by CSA Global and completed by Andrada
comprised 26 DD holes drilled in six fences, spaced approximately 200 m apart
and spanning the main part of the V1/V2 pegmatite. Hole spacing on the fences
ranges between 30 m and 70 m for the most part, with a final line of deep
holes spaced 200 m from the previous DD hole drilled by Andrada.
These DD drillholes supplement the ISCOR drilling which has an average drill
density of one hole every 50 m (spaced 25 m along strike) on an irregular grid
constrained by access and highwall positions.
The current 2021-2022 drilling program executed by Andrada comprised 22 DD
holes and 29 RC holes drilled spanning the main part of the V1/V2 pegmatite as
infill to the 2019 drilling program resulting in a nominal 60 m drillhole
spacing.
The MRE and classification were based on the sufficiency and spacing of the
drillholes. For tin, variographic analyses is robust and the resulting
estimates have been classified according to estimation precision using
ordinary kriging parameters. The downhole semi-variogram has a relatively high
nugget variance (about 50%), and a short range of about 5 m, but is well
structured.
Criteria JORC Code explanation Commentary
Variography for lithium, niobium and tantalum is not robust with the exception
of the downhole direction; the primary reason for this is likely to be the
data paucity for these three elements. All estimates for these three analytes
were classified as Inferred Mineral Resources.
Whilst the grade variability is highly nuggety the overall geology, which
defines the mineralised pegmatite is continuous over the extent of the model.
Drilling spacing is adequate for a high degree of confidence in the
mineralised model. Xenoliths of waste within the pegmatite are less continuous
and can be defined with a moderate level of confidence. The xenoliths are
expected to be limited in extent, supported by observations in the current
excavation on site.
Sample compositing has not been undertaken at the exploration or sampling
stage.
Orientation of data in relation to geological structure Whether the orientation of sampling achieves unbiased sampling of possible In most cases, the drillholes were drilled vertically. In the instances where
structures and the extent to which this is known, considering the deposit the drillhole was angled the orientation of drillholes is perpendicular to the
type. strike of the intrusion/sigmoidal shape of the pegmatite intrusive deposit.
Due to the undulatory nature of the intrusion, the primarily vertical
orientation of the drillholes was chosen to reduce bias in any specific
orientation.
Orientated drillholes were sited in areas where the attitude of the pegmatite
below surface was known with a relatively high level of confidence.
Sample security The measures taken to ensure sample security. ISCOR
No information was available regarding the sample security of historical
samples.
Andrada
All sampling and sample processing (cutting, tagging, packaging and loading)
was conducted within the core shed by qualified geologists or technicians
under the supervision of the geologists. Work was carried out according to
sample lists prepared by the geologist using the acQuire database software in
2019 and using an in-house database for the 2022 drilling.
Samples were processed individually wherever possible to reduce the chance of
sample swapping occurring.
Sample processing in the laboratory was undertaken by trained technical staff
and the chain of custody was followed.
Audits or reviews The results of any audits or reviews of sampling techniques and data. A representative of ERM, Michael Cronwright, undertook a site visit during the
2022 infill drill program to review the drilling, sampling and QAQC procedures
and reported these practices to be acceptable.
Mr Anthony Wesson conducted a site visit in August 2018 during the first phase
of drilling by Andrada.
No further audits have been undertaken.
Section 2: Reporting of Exploration Results
Criteria JORC Code explanation Commentary
Mineral tenement and land tenure status Type, reference name/number, location and ownership including agreements or Exploration activities occurred on mining licence (ML) 134, issued to Guinea
material issues with third parties such as joint ventures, partnerships, Fowl Investments Twenty Seven (Pty) Ltd (Guinea Fowl). ML 134 expires in 2028
overriding royalties, native title interests, historical sites, wilderness or and is renewable under Namibian Mining Law. The Guinea Fowl company name was
national park and environmental settings. changed to Uis Tin Mining Company (UTMC) at the end of 2019.
The security of the tenure held at the time of reporting along with any known Andrada, through a Namibian subsidiary, initially controlled 85% of UTMC with
impediments to oaining a licence to operate in the area. the remaining 15% controlled by the Small Miners of Uis (SMU), a
not-for-profit company owned by the Namibian government. In August 2024 an
agreement was reached between Andrada and the SMU which resulted in Andrada
acquiring 100% of the mining license ML 134.
The area investigated in this report is classified as state land, as a result
no compensation agreement is required prior to commencement of operations. The
deposit lies within the historical Uis Tin Mine licence area. This area was
previously extensively mined and no rehabilitation was carried out prior to
closure. Due to this existing impact the area is not considered
environmentally sensitive. Andrada has also been issued with a valid
Environmental Clearance Certificate which allows mining and exploration
activities to be conducted.
Exploration done by other parties Acknowledgment and appraisal of exploration by other parties. Exploration was carried out by ISCOR between the early 1960s and 1989. The
resulted in a reserve and mine plan being compiled by SRK in 1989, a few
months before mining operations ceased.
A significant portion of the exploration data was obtained and digitised by
Andrada. Relevant information has been validated by current exploration
activities and utilised in this report.
As the ISCOR drilling was used to inform the tin estimate, it was necessary to
evaluate if they were appropriate to use for the MRE. Some basic statistical
checks, which included simple histograms and cumulative frequency plots, were
augmented by a comparison of the downhole experimental semivariograms. All
parameters, such as means and variances of the composited data, were
considered of similar tenor and the similarity of the semi-variogram
parameters further supported using the two datasets jointly for the MRE.
As further validation, a number of twinned drillholes were drilled adjacent to
ISCOR drillholes as part of
Andrada's 2019 program. Unsurprisingly, because of the nuggety nature of the
cassiterite (tin) distribution, the correlation between samples from the
twinned holes varied between good and not correlated although, in general, the
widths of the mineralised intercepts showed reasonable agreement. This was not
considered to be a risk, as when comparing the grades of consecutive downhole
2 m composites, high variability was apparent as indicated by the
semi-variogram.
Geology Deposit type, geological setting and style of mineralisation. The deposit is hosted within the Damara Orogen, a typical pan African-aged
(750-440 Ma) orogenic belt which represents the assembly of Gondwana during
which the Congo, Rio De la Plata and Kalahari cratons collided within a triple
point located in Swakopmund, Namibia.
Orogenesis produced voluminous quantities of granitic magmatism during the
syn-tectonic phases of collision. This was followed by a pegmatitic phase of
magmatism in the post-tectonic environment, populating the Damara Orogen with
numerous pegmatitic intrusions
Criteria JORC Code explanation Commentary
The V1 and V2 pegmatites are magmatic intrusive bodies with sigmoidal shapes
in plan. They formed when a low viscosity and undercooled magma crystallised
to form a pegmatite. Various alteration types are present and related to the
emplacement, crystallisation and cooling of the pegmatite The pegmatites
strike to the northeast and dip to the northwest at between 30° and 50°.
The mineralisation style is primarily magmatic although some may be alteration
related.
Primary cassiterite crystallised during the late stages of the magmatic phases
of the pegmatites crystallisation history when sufficient magmatic
fractionation has increased the abundance of Li and Sn to insoluble levels.
The lithium mineralisation crystalised as petalite during this time as well
along with the bulk of the other silicate minerals like feldspar, quartz and
muscovite.
The pegmatite then exsolved an aqueous fluid when water and flux saturation
was reached. Elements such as tin, tantalum, lithium, boron, rubidium and
niobium segregated into this fluid. This fluid then resulted in significant
amounts of resorption and replacement of magmatic assemblages in places to
form a quartz-muscovite assemblage known as a greisen. Simultaneous and
abundant cassiterite crystallisation occurred during this alteration phase.
Drillhole information A summary of all information material to the understanding of the exploration See table in this report and announcements for collar and survey data for
results including a tabulation of the following information for all Material newly acquired drillholes used in this Mineral Resource update.
drillholes:
The subject of this JORC report is an MRE and exploration results are not
x Easting and northing of the drillhole collar x Elevation or RL (Reduced being reported. The relevance of the individual characteristics of each
Level - elevation above sea level in metres) of the drillhole collar drillhole is superseded by the interpretation that is created using all the
drillholes. The quality of the data used, and the assumptions around their
x Dip and azimuth of the hole x Downhole length and interception depth x Hole use, are documented here.
length.
All relevant information has been reported in press releases by Andrada, and
If the exclusion of this information is justified on the basis that the available on their website
information is not Material and this exclusion does not detract from the
understanding of the report, the Competent Person should clearly explain why (https://andradamining.com/media/rns/) on the following dates: 20 May 2019, 10
this is the case. June 2019 and 26 June
2019, 16 September 2019 (MRE), 11 October 2021, 8 June 2022, 20 July 2022, 11
October 2022, 22 November 2022, 5 December 2022, 31 January 2023, 2 February
2023, 6 February 2023 (MRE update) and 30 March 2023.
Data aggregation methods In reporting Exploration Results, weighting averaging techniques, maximum Not relevant; Exploration Results are not being reported here. Mineral
and/or minimum grade truncations (e.g. cutting of high grades) and cut-off Resources are being disclosed (see Section 3).
grades are usually Material and should be stated.
Criteria JORC Code explanation Commentary
Where aggregate intercepts incorporate short lengths of high grade results and
longer lengths of low grade results, the procedure used for such aggregation
should be stated and some typical examples of such aggregations should be
shown in detail.
The assumptions used for any reporting of metal equivalent values should be
clearly stated.
Relationship between mineralisation widths and intercept lengths These relationships are particularly important in the reporting of Exploration Not relevant; Exploration Results are not being reported here. Mineral
Results. Resources are being disclosed (see Section 3).
If the geometry of the mineralisation with respect to the drillhole angle is
known, its nature should be reported.
If it is not known and only the downhole lengths are reported, there should be
a clear statement to this effect (e.g. 'downhole length, true width not
known').
Diagrams Appropriate maps and sections (with scales) and tabulations of intercepts Relevant maps and diagrams are included in the body of the report, to which
should be included for any significant discovery being reported These should this report applies.
include, but not be limited to a plan view of drillhole collar locations and
appropriate sectional views.
Balanced reporting Where comprehensive reporting of all Exploration Results is not practicable, Not relevant; Exploration Results are not being reported here. Mineral
representative reporting of both low and high grades and/or widths should be Resources are being disclosed (see Section 3).
practiced to avoid misleading reporting of Exploration Results.
Other substantive exploration data Other exploration data, if meaningful and material, should be reported Andrada carried out extensive mapping of the V1/V2 pegmatite which has been
including (but not limited to): geological observations; geophysical survey used to constrain the geological model.
results; geochemical survey results; bulk samples - size and method of
treatment; metallurgical test results; bulk density, groundwater, geotechnical The extensive historical dataset from ISCOR was statistically validated and
and rock characteristics; potential deleterious or contaminating substances. used to support the MRE.
Further work The nature and scale of planned further work (e.g. tests for lateral Processing testwork related to the petalite-hosted lithium mineralisation is
extensions or depth extensions or large-scale step-out drilling). ongoing.
Other recommendations have been made in Section 11 of this report.
Criteria JORC Code explanation Commentary
Diagrams clearly highlighting the areas of possible extensions, including the
main geological interpretations and future drilling areas, provided this
information is not commercially sensitive.
Section 3: Estimation and Reporting of Mineral Resources
Criteria JORC Code explanation Commentary
Database integrity Measures taken to ensure that data has not been corrupted by (e.g. The information was captured into an auditable sequel database which was
transcription or keying errors) between its initial collection and its use for developed with the assistance of Andrada. The entries were checked and
Mineral Resource estimation purposes. verified by a database administrator to ensure accuracy.
Data validation procedures used. Data used in the MRE (Section 3) was sourced from an export from the database
system into csv format for use in Isatis.
Validation checks were carried out on the data imported which included checks
for overlapping intervals, missing survey data, missing lithological data and
missing collars.
Site visits Comment on any site visits undertaken by the Competent Person and the outcome A site visit was undertaken by the Competent Person, Anthony Wesson, in
of those visits. October 2018, at which time Andrada was undertaking infill and extensional
drilling. The core logging procedure was explained, and logging was observed
If no site visits have been undertaken, indicate why this is the case. against these procedures. As part of the site visit a sampling and assaying
QAQC program was discussed with and agreed upon with Andrada representatives.
A visit to the UIS laboratory in Midrand was undertaken to discuss the
requirements of the QAQC program with laboratory staff.
The most recent site visit was undertaken by Michael Cronwright in June 2022
during Andrada's infill RC and DD drilling program on the V1/V2 pegmatites.
The core logging and sampling procedure was explained, and logging was
observed. Some checks on the logging and sampling intervals were conducted as
well as confirmation of collar locations in the field.
Geological interpretation Confidence in (or conversely, the uncertainty of) the geological There is high confidence in the interpretation at surface, due to close spaced
interpretation of the mineral deposit. drilling supported by surface mapping. Confidence reduces at depth due to
drill spacing.
Nature of the data used and of any assumptions made.
A 3D geological model has been constructed using drillhole logging and surface
The effect, if any, of alternative interpretations on Mineral Resource mapping.
estimation.
Alternate interpretations are limited close to surface, apparent steepening of
The use of geology in guiding and controlling Mineral Resource estimation. The dip at depth is supported by limited drilling, further drilling may result in
factors affecting continuity both of grade and geology. a change of interpretation at depth. Apparent reduction in xenoliths with
depth may be a function of drill spacing.
The pegmatite vein has been used as a constraint to mineralisation.
Geological grade and continuity are controlled by the presence of pegmatite,
there is no zonation evident in the geology, supported by a single grade
population for tin.
The presence of diluting xenoliths, which occur as discreet units within the
pegmatite, is difficult to estimate and model. They occur at random and are
not continuous hole to hole. The effect of these xenoliths is expected to be
minor from in pit and surface observations.
Criteria JORC Code explanation Commentary
Geological wireframes were composed from drillhole logging, the wireframes
were utilised to code the drillholes and to generate a proportional block
model
Dimensions The extent and variability of the Mineral Resource expressed as length (along The V1 and V2 pegmatites are exposed in the V1/V2 pit and are two of the
strike or otherwise), plan width, and depth below surface to the upper and largest pegmatites on ML 134. The V1 pegmatite is exposed in the northeast of
lower limits of the Mineral Resource. the pit, and the V2 in the northwest and the pegmatites merge within the pit.
The V1 pegmatite extends strikes northeast-southwest for approximately 600 m,
dipping at 50° to the northwest, with an average thickness of about 25 m. In
the western portion of the pit, the V1 Pegmatite merges with the V2 Pegmatite
and the pegmatite dips at 30-40° to the northwest and west-northwest,
discordant to the country-rock schist which dips to the southeast.
The V2 Pegmatite is around 10 m thick in the east, but thickens to >40 m
towards the southwest, along the northwestern highwall of the pit where it
merges with the V1 pegmatite, and dips into the northwest highwall. It is
exposed along the entire northwest pit face and is traceable within the pit
and for at least 650 m on surface to the southwest or south-southwest.
Together, the V1 and V2 pegmatites extend along a northeast-southwest strike
distance of over approximately 1.2 km, and consistently reach thicknesses of
over 20 m.
Estimation and modelling techniques The nature and appropriateness of the estimation technique(s) applied and key An in-situ MRE was undertaken for the two pegmatite bodies referred to as the
assumptions, including treatment of extreme grade values, domaining, V1 and V2 pegmatites.
interpolation parameters and maximum distance of extrapolation from data
points. If a computer assisted estimation method was chosen, include a Raw data were loaded and used to build the geological model; part of the
description of computer software and parameters used. process included coding the drillholes by geology/lithology then exporting
those coded data from Datamine software to Isatis software for geostatistical
The availability of check estimates, previous estimates and/or mine production analyses. Once the data were loaded into Isatis and prior to composting, the
records and whether the MRE takes appropriate account of such data. raw data statistics were generated by geological domain and compared to the
input data file statistics on the same basis. After compositing to 2 m, the
The assumptions made regarding recovery of byproducts. data statistics were compared to the raw data to confirm that the compositing
procedure generated reliable results and that residuals were treated as
Estimation of deleterious elements or other non-grade variables of economic follows:
significance (e.g. sulphur for acid mine drainage characterisation).
x If the analysed length of the last core at the end of the line was smaller
In the case of block model interpolation, the block size in relation to the than 50% of the composite length, it was ignored
average sample spacing and the search employed.
x If the analysed length of the last core was greater than 50% of the
Any assumptions behind modelling of selective mining units. composite length, it was kept as it is.
Any assumptions about correlation between variables. Correlation between all variables was low with no pair having a correlation
greater than 0.4.
Description of how the geological interpretation was used to control the
resource estimates. The MRE was carried out for tin, lithium, niobium, rubidium and tantalum by
ordinary kriging into a block model of 20 m x 20 m x 10 m (X x Y x Z). The
block size was selected after sensitivity analyses were undertaken on a range
of block sizes with an emphasis on the grade/tonnage sensitivity around the
expected cut-off grade. This is an operating mine, and the block dimensions
are appropriate given the size of the mining fleet and the scale of
operations.
The shape of the distributions of all five elements as described by their
coefficient of variations (CVs) is low (0.3 to 0.6), nevertheless, top cutting
was applied to tin (1.0% Sn) for both the V1 and V2 pegmatites but made
minimal difference to the average-declustered grade.
Criteria JORC Code explanation Commentary
Discussion of basis for using or not using grade cutting or capping. The quality of the experimental variography is element dependent and ranges
from poor to moderate.
The process of validation, the checking process used, the comparison of model
data to drillhole data, and use of reconciliation data if available. Although tin has significantly more 2 m composites for modelling than the
other elements, a short scale, 50 m, first structure accounting for between
70% and 80% of the total variance, generates, by design, smoothed estimates
appropriate for a global estimate and an operation which is non-selective and
mines the entire Mineral Resource model.
Estimation of the five elements was carried out in three passes, each time
extending the search ellipse and decreasing the minimum number of samples to
be used for estimation. The first pass search ellipse had the same dimensions
as the semi-variogram ranges. Subsequent estimation passes were extended, and
the minimum number of samples used was reduced until in the third pass the
minimum was set to four samples. No attempt was made to fill all blocks with
estimates for any or all elements as this would have resulted in unwanted
extrapolation and poor-quality estimates based on the assessment of the slope
of regression (SOR) metric and distance from the nearest samples. Estimation
was constrained to 50 m from the nearest samples.
Estimates were validated by comparing graphical sections showing block grades
vs composite grades, domain averages with de-clustered means and by trend
(swath) plots.
The previous MRE was carried out by ERM (as CSA Global) in September 2019 when
only tin material was classified as Measured, Indicated and Inferred, and all
tantalum and Li(2)O Mineral Resources were classified as Inferred. Estimated
grades for tin, tantalum and Li(2)O are similar between the two models, but
tonnages have increased due to infill and extensional drilling.
No previous production records are available for reconciliation with the
model.
The estimate has been reported below the current mined surface, with depleted
material being removed from the model.
Moisture Whether the tonnages are estimated on a dry basis or with natural moisture, Tonnages have been estimated on a dry, in-situ basis with no allowance for
and the method of determination of the moisture content. porosity although given the crystalline and unweathered nature of the
pegmatite, porosity is considered negligible.
Cut-off parameters The basis of the adopted cut-off grade(s) or quality parameters applied. The entire Mineral Resource will be consumed using the current parameters
tabulated below.
Mining factors or assumptions Assumptions made regarding possible mining methods, minimum mining dimensions It has been assumed that the deposit is amenable to open cut mining methods
and internal (or, if applicable, external) mining dilution. It is always and are potentially economic to exploit to the depths indicated by the pit
necessary as part of the process of determining reasonable prospects for shell optimisation exercise.
eventual economic extraction to consider potential mining methods, but the
assumptions made regarding mining methods and parameters when estimating An in-situ Mineral Resource model was generated using a block size of 20 m x
Mineral Resources may not always be rigorous. Where this is the case, this 20 m x 10 m without dilution factors applied. Mining will be undertaken by
should be reported with an explanation of the basis of the mining assumptions truck (80-tonne) and shovel.
made.
A bulk mining scenario has been assumed, and lithium and tantalum have been
considered as byproducts and have not been used to inform revenue.
A pit shell at a revenue factor (RF) of 1.0 was created in Datamine Studio
NPVS(TM) software to support the reporting of Mineral Resources. The
parameters used to undertake the pit shell optimisation are provided below and
parameters supplied by Andrada were reviewed for reasonableness by ERM:
Parameter Unit Value Comments and source
Criteria JORC Code explanation Commentary
Base currency US$
Resource categories to be optimised Measured + Indicated + Inferred
Commodity Li and Sn
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x
Reha
bili
tati
on
US$/
t
0.07
Over
all
slop
e
angl
e
°
55
RPEE
E_pa
rame
ters
.xls
x
Pet
alit
e
LI
unit
in
bloc
k
mode
l
ppm
-
Li %
%
Li/1
0000
Li(
2)O
%
%
(Li
ppm/
1000
0)*2
.153
Peta
lite
conc
entr
ate
pric
e
US$
/con
c t
1500
Peta
lite
paya
blit
y
%
100
Roya
lty
%
3
Peta
lite
proc
essi
ng
reco
very
%
45
Peta
lite
conc
entr
ate
grad
e
%
4
Peta
lite
proc
essi
ng
cost
US$/
t
ore
3.5
Pet
alit
e
logi
stic
cost
US$/
t
conc
155
Pet
alit
e
sale
s
comm
issi
on
US$/
t
conc
-
Pet
alit
e
trea
tmen
t
char
ge
and
pena
ltie
s
US$/
t
conc
-
Ove
rhea
ds
US$/
t
conc
-
Sn
Sn price US$/t 25,500
Sn concentrate price US$/conc t 15,300
Royalty % 3
Sn processing recovery % 80
Sn concentrate grade % 60 76% SnO(2) conc grade
Sn processing cost US$/t ore 3.75
Sn logistic cost US$/t conc 155
Sn sales commission US$/t conc -
Sn treatment charge and penalties US$/t conc 985
Overheads US$/t conc 1250
Petalite
LI unit in block model ppm -
Li % % Li/10000
Li(2)O % % (Li ppm/10000)*2.153
Petalite concentrate price US$/conc t 1500
Petalite payablity % 100
Royalty % 3
Petalite processing recovery % 45
Petalite concentrate grade % 4
Petalite processing cost US$/t ore 3.5
Petalite logistic cost US$/t conc 155
Petalite sales commission US$/t conc -
Petalite treatment charge and penalties US$/t conc -
Overheads US$/t conc -
Sn
Sn price
US$/t
25,500
Sn concentrate price
US$/conc t
15,300
Royalty
%
3
Sn processing recovery
%
80
Sn concentrate grade
%
60
76% SnO(2) conc grade
Sn processing cost
US$/t ore
3.75
Sn logistic cost
US$/t conc
155
Sn sales commission
US$/t conc
-
Sn treatment charge and penalties
US$/t conc
985
Overheads
US$/t conc
1250
Criteria JORC Code explanation Commentary
Metallurgical factors or assumptions The basis for assumptions or predictions regarding metallurgical amenability. Historical recoveries reported by ISCOR and internal Andrada testwork support
It is always necessary as part of the process of determining reasonable the recovery of 80% Sn and the production of a 60% Sn concentrate which have
prospects for eventual economic extraction to consider potential metallurgical been used to generate the pit shell from which Mineral Resources have been
methods, but the assumptions regarding metallurgical treatment processes and reported. The resulting concentrates include up to 1.5% Ta content which can
parameters made when reporting Mineral Resources may not always be rigorous. be separated magnetically, although the economic viability of doing this
Where this is the case, this should be reported with an explanation of the remains to be ascertained. Lithium mineralogy, based on available xray
basis of the metallurgical assumptions made. diffraction (XRD) data and some test work that has been completed and
reported, appears to be petalite dominated which will aid the potential
production of a lithium concentrate.
Environmental factors or assumptions Assumptions made regarding possible waste and process residue disposal ERM has not undertaken a review of the environmental factors that may be
options. It is always necessary as part of the process of determining associated with the project and these will be covered in detail in subsequent
reasonable prospects for eventual economic extraction to consider the phases of study work. Andrada hold a valid Mining Permit with contingent
potential environmental impacts of the mining and processing operation. While environmental responsibilities that will need to be adhered to in order to
at this stage the determination of potential environmental impacts, advance the project.
particularly for a greenfields project, may not always be well advanced, the
status of early consideration of these potential environmental impacts should
be reported. Where these aspects have not been considered, this should be
reported with an explanation of the environmental assumptions made.
Bulk density Whether assumed or determined. If assumed, the basis for the assumptions. If Dry bulk density has been based on specific gravity of samples, determined by
determined, the method used, whether wet or dry, the frequency of the commercial pycnometric methods. This is considered appropriate given the
measurements, the nature, size and representativeness of the samples. competent, crystalline nature of the pegmatite. For every sample collected by
Andrada, a SG was measured using the pycnometer method which is considered
The bulk density for bulk material must have been measured by methods that equivalent to the dry bulk density. The range of dry bulk densities for the
adequately account for void spaces (vugs, porosity, etc.), moisture and pegmatites is low (2.55 t/m(3) to 2.83 t/m(3)) with an average value of 2.65
differences between rock and alteration zones within the deposit. t/m(3). The average density value of 2.65 was used in the block model.
Discuss assumptions for bulk density estimates used in the evaluation process
of the different materials.
Criteria JORC Code explanation Commentary
Classification The basis for the classification of the Mineral Resources into varying In the first instance, classification was assigned based on geological
confidence categories. interpretation of the V1/V2 orebodies and the ordinary kriging output metrics,
the SOR and kriging efficiency (KE). The SOR generates values between zero and
Whether appropriate account has been taken of all relevant factors (i.e. unity and as with most regression analyses, unity means perfect correlation
relative confidence in tonnage/grade estimations, reliability of input data, and the lower the value, the poorer the estimate is. Another useful measure of
confidence in continuity of geology and metal values, quality, quantity and estimation confidence is the KE; it is a measure of the ratio of the
distribution of the data). estimation variance to that of the block variance and ranges from negative
values to unity; it is a measure of estimation smoothing, a value of zero or
Whether the result appropriately reflects the Competent Person's view of the negative values means that the estimation variance is equal to or greater than
deposit. the block variance and a KE of zero is equivalent to an SOR of 0.5. When the
estimation variance is equal to the block variance, it is more efficient to
apply the mean of the domain, if it can be precisely measured, to those blocks
with negative KE values.
No attempt was made to fill all blocks within the geological/estimation
domains with grade estimates. It is the norm, that when working with multiple
elements, the element which generates the lowest confidence estimates is used
to guide classification. For V1 it is clearly tin, and in V2 it is lithium
followed by tin, and for consistency, the tin SOR was used to define the
classification system.
Any SOR >0.5 means that the estimate of a block is better than assigning
the global average to the block. The initial classification assignment was as
follows: x Measured Mineral Resources, a SOR >0.8 was required x Indicated
Mineral Resources, a SOR >0.6 was required.
All other Mineral Resources not already classified and constrained to blocks
not more than 50 m from at least four samples, were classified as Inferred
Mineral Resources. However, it was found that Measured and Indicated Mineral
Resources were interspersed, therefore boundaries between the two categories
were imposed guided by the SOR and distances from informing samples.
Only blocks which have all elements estimated (tin, lithium, niobium,
rubidium, tantalum), have been classified and reported in the Mineral
Resources table.
Audits or reviews The results of any audits or reviews of MREs. Internal audits and peer review were completed by ERM which verified and
considered the technical inputs, methodology, parameters and results of the
estimate.
No external audits have been undertaken.
Discussion of relative accuracy/ confidence Where appropriate, a statement of the relative accuracy and confidence level As this is an operating mine, reconciliation between the mined and modelled Sn
in the MRE using an approach or procedure deemed appropriate by the Competent grade is reported to be within an acceptable range (±15%). No reconciliation
Person. For example, the application of statistical or geostatistical information for Li is available yet.
procedures to quantify the relative accuracy of the resource within stated
confidence limits, or, if such an approach is not deemed appropriate, a This is a global estimate reported without the application of a cut-off grade
qualitative discussion of the factors that could affect the relative accuracy as the entire Mineral Resource is within the optimised pit shell. Estimates
and confidence of the estimate. are intentionally smoothed as no cut-off has been applied and the tin
semi-variograms have a short-range high variance component. Tin and lithium
are the main economic drivers of the Uis Mine operation.
The following neighbourhood parameters were considered for each of the
elements: x The initial search ellipse was set to the semi-variogram ranges.
Criteria JORC Code explanation Commentary
The statement should specify whether it relates to global x The minimum and maximum numbers of samples were chosen so that a
consistently good SOR and KE could be achieved. The quality of these two
or local estimates, and, if local, state the relevant tonnages, which should parameters is largely a function of the number of samples used and the
be relevant to technical and economic evaluation. Documentation should include semi-semi-variogram models.
assumptions made and the procedures used.
The sum of positive weights was reviewed and by default the sum of the
These statements of relative accuracy and confidence of the estimate should be negative weights. A small percentage of negative weights (< 2%) is
compared with production data, where available. acceptable because that gives an indication that the search distances have
been extended sufficiently far enough.
The importance of the weight of the mean (WOM) should not be underestimated. A
high WOM implies that the local mean grade is well known and increases when a
restricted estimation neighbourhood is applied. Ideally, the WOM should be
around 10% to 15%.
The ranges chosen for the first pass were set to the semi-variogram ranges so
that the constraint is the number of samples, not the ranges. The second pass
usually entails dropping the minimum number of samples while extending the
search ellipse. The third pass can extend beyond the ranges and the search
ellipse from the previous two passes and may include a further reduction to
the minima.
Some constraints were placed on the number of samples used from a drillhole to
ensure that more than one drillhole was accessed.
Restrictions to the maximum distance without a sample were imposed to
constrain estimates, so that extrapolation was kept to reasonable distances
less than 50 m.
Tin in V2 was estimated with a restricted neighbourhood to compare the
estimates with that of the MRE to assess the similarities/differences. As was
expected, the local biases were evident, but the global estimate was identical
considering that no cut-off was applied to the Mineral Resource model.
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