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%
Li2O from 0.73% Li2O declared in
2023¹
− Contained lithium
oxide ("Li2O") 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
²
https://polaris.brighterir.com/public/andrada_mining/news/rns/story/x8en45x
³
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 %
Li2O, 0.15 % Sn and 82 ppm Ta. This MRE includes 27.33
mt at an average grade of 0.82 % Li2O, 0.15 % Sn and 90
ppm Ta for the near surface Measured category, 17.50 mt at an
average grade of 0.79 % Li2O, 0.15 % Sn and 86 ppm Ta
for the Indicated category, and 32.68 mt with an average grade of
0.76 % Li2O, 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
(ppm)
|
Li2O
(%)
|
Rb
(ppm)
|
Ta
(ppm)
|
Nb
(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
|
Li2O
|
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% Li2O
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 Li2O (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)
|
Li2O
%
|
Contained Li2O
(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 (Ta2O5) and columbite
(Nb2O5) that host Ta and Nb mineralisation in pegmatite
deposits.
|
|
DD
|
Diamond
core drilling
|
|
LCE
|
Lithium
Carbonate Equivalent.
|
|
Li
|
Symbol
for Lithium
|
|
Li →
Li2O
|
Metal to
metal-oxide conversion factor of 2.153
|
|
Li →
LCE
|
Metal to
lithium carbonate equivalent conversion factor of 5.323
|
|
Li2O
|
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
(LiAlSi4O10) 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
Andrada Mining
Anthony
Viljoen, CEO
Sakhile
Ndlovu, Investor Relations
|
+27 (11)
268 6555
|
NOMINATED ADVISOR &
BROKER
|
|
Zeus Capital Limited
Katy
Mitchell
Harry
Ansell
Andrew de
Andrade
|
+44 (0) 20 2382
9500
|
CORPORATE BROKER &
ADVISOR
|
|
H&P Advisory Limited
Andrew
Chubb
Jay
Ashfield
Matt
Hasson
|
+44 (0)
20 7907 8500
|
Berenberg
Jennifer
Lee
Natasha
Ninkov
|
+44 (0)
20 3753 3040
|
FINANCIAL PUBLIC
RELATIONS
|
|
Tavistock (United Kingdom)
Emily
Moss
Josephine
Clerkin
|
+44 (0)
207 920 3150
andrada@tavistock.co.uk
|
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 specialised
industry standard measurement tools appropriate to the minerals
under investigation, such as downhole gamma sondes, or handheld XRF
instruments, etc.). These examples should not be taken as limiting
the broad meaning of sampling.
Include reference to
measures taken to ensure sample representivity and the appropriate
calibration of any measurement tools or systems
used.
Aspects of the determination
of mineralisation that are Material to the Public Report. In cases
where 'industry standard' work has been done this would be
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 assay'). In other cases, more explanation may be
required, such as where there is coarse gold that has inherent
sampling problems.
Unusual commodities or
mineralisation types (e.g.
submarine nodules) may
warrant disclosure of detailed information
|
ISCOR
Historical
drilling completed by ISCOR (Iron and Steel Corporation (Pty) Ltd)
was used and in the exploration database and comprised 13 diamond
(DD) 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 sampling protocols, there is
evidence that investigations into sample reproducibility and
repeatability were carried out and the nuggety nature of the tin
mineralisation was recognised. Despite this local variability, the
average grade of tin appeared to be consistent around 0.14% Sn,
similar to what has been estimated in this MRE. Andrada
2018 to
2019
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 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 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 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, whether core is oriented and if so, by what method,
etc.).
|
ISCOR
Available
archive material sets out that an Atlas Copco ROC61 percussion rig,
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
assessed.
Measures taken to maximise
sample recovery and ensure representative nature of the
samples.
Whether a relationship
exists between sample recovery and grade and whether sample bias
may have occurred due to preferential loss/gain of fine/coarse
material.
|
ISCOR
No
recovery information was available.
Andrada
2018 to
2019
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 to a level
of detail to support appropriate Mineral Resource estimation,
mining studies and metallurgical studies.
|
ISCOR
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.
If non-core, whether
riffled, tube sampled, rotary split, etc. and whether sampled wet
or dry.
For all sample types, the
nature, quality and appropriateness of the sample preparation
technique.
Quality control procedures
adopted for all subsampling stages to maximise representivity of
samples.
Measures taken to ensure
that the sampling is
representative of the
in-situ material collected, including for instance results for
field duplicate/second-half sampling.
Whether sample sizes are
appropriate to the grain size of the material being
sampled.
|
ISCOR
No
information about subsampling for the historical drilling was
available.
Andrada
2018 to
2018
Approximately 33% of drillholes were sampled as full core,
with the remainder sampled as half core.
The
full-core analysis was utilised to test the nugget effect and
determine potential bias associated with sample size. No bias was
detected, and half-core samples are considered reliable for their
use in the MRE.
The sample
size used is appropriate for the coarse-grained nature of the
pegmatite deposit as the largest diamond core drill size
commercially 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 procedures used and
whether the technique is considered partial or
total.
|
ISCOR
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 alternative
company personnel.
|
Two site
visits were conducted during the drill programmes completed to date
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 surveys),
trenches, mine workings and other locations used in Mineral
Resource estimation.
|
ISCOR
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 structures and the
extent to which this is known, considering the deposit
type.
|
In most
cases, the drillholes were drilled vertically. In the instances
where the drillhole was angled the orientation of drillholes is
perpendicular to the 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 material issues with
third parties such as joint ventures, partnerships, overriding
royalties, native title interests, historical sites, wilderness or
national park and environmental settings.
The security of the tenure
held at the time of reporting along with any known impediments to
oaining a licence to operate in the area.
|
Exploration activities occurred on mining licence (ML) 134,
issued to Guinea Fowl Investments Twenty Seven (Pty) Ltd (Guinea
Fowl). ML 134 expires in 2028 and is renewable under Namibian
Mining Law. The Guinea Fowl company name was changed to Uis Tin
Mining Company (UTMC) at the end of 2019.
Andrada,
through a Namibian subsidiary, initially controlled 85% of UTMC
with 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 results including
a tabulation of the following information for all Material
drillholes:
x
Easting and
northing of the drillhole collar x Elevation or RL (Reduced Level - elevation above sea level in
metres) of the drillhole collar
x
Dip and azimuth
of the hole x Downhole length and
interception depth x
Hole
length.
If the exclusion of this
information is justified on the basis that the information is not
Material and this exclusion does not detract from the understanding
of the report, the Competent Person should clearly explain why this
is the case.
|
See table
in this report and announcements for collar and survey data for
newly acquired drillholes used in this Mineral Resource
update.
The
subject of this JORC report is an MRE and exploration results are
not being reported. The relevance of the individual characteristics
of each drillhole is superseded by the interpretation that is
created using all the drillholes. The quality of the data used, and
the assumptions around their use, are documented here.
All
relevant information has been reported in press releases by
Andrada, and available on their website
(https://andradamining.com/media/rns/)
on the following dates: 20 May 2019, 10 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 and/or minimum
grade truncations (e.g. cutting of high grades) and cut-off grades
are usually Material and should be stated.
|
Not relevant; Exploration Results
are not being reported here. Mineral Resources are being disclosed
(see Section 3).
|
|
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
Results.
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').
|
Not relevant; Exploration Results
are not being reported here. Mineral Resources are being disclosed
(see Section 3).
|
|
Diagrams
|
Appropriate maps and
sections (with scales) and tabulations of intercepts should be
included for any significant discovery being reported These should
include, but not be limited to a plan view of drillhole collar
locations and appropriate sectional views.
|
Relevant
maps and diagrams are included in the body of the report, to which
this report applies.
|
|
Balanced
reporting
|
Where comprehensive
reporting of all Exploration Results is not practicable,
representative reporting of both low and high grades and/or widths
should be practiced to avoid misleading reporting of Exploration
Results.
|
Not relevant; Exploration Results
are not being reported here. Mineral Resources are being disclosed
(see Section 3).
|
|
Other substantive exploration
data
|
Other exploration data, if
meaningful and material, should be reported including (but not
limited to): geological observations; geophysical survey results;
geochemical survey results; bulk samples - size and method of
treatment; metallurgical test results; bulk density, groundwater,
geotechnical and rock characteristics; potential deleterious or
contaminating substances.
|
Andrada
carried out extensive mapping of the V1/V2 pegmatite which has been
used to constrain the geological model.
The
extensive historical dataset from ISCOR was statistically validated
and used to support the MRE.
|
|
Further
work
|
The nature and scale of
planned further work (e.g. tests for lateral extensions or depth
extensions or large-scale step-out drilling).
|
Processing
testwork related to the petalite-hosted lithium mineralisation is
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. transcription or keying
errors) between its initial collection and its use for Mineral
Resource estimation purposes.
Data validation procedures
used.
|
The
information was captured into an auditable sequel database which
was developed with the assistance of Andrada. The entries were
checked and verified by a database administrator to ensure
accuracy.
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 of those
visits.
If no site visits have been
undertaken, indicate why this is the case.
|
A site
visit was undertaken by the Competent Person, Anthony Wesson, in
October 2018, at which time Andrada was undertaking infill and
extensional drilling. The core logging procedure was explained, and
logging was observed 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 interpretation of
the mineral deposit.
Nature of the data used and
of any assumptions made.
The effect, if any, of
alternative interpretations on Mineral Resource
estimation.
The use of geology in
guiding and controlling Mineral Resource estimation. The factors
affecting continuity both of grade and geology.
|
There is
high confidence in the interpretation at surface, due to close
spaced drilling supported by surface mapping. Confidence reduces at
depth due to drill spacing.
A 3D
geological model has been constructed using drillhole logging and
surface mapping.
Alternate
interpretations are limited close to surface, apparent steepening
of dip at depth is supported by limited drilling, further drilling
may result in 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 strike or
otherwise), plan width, and depth below surface to the upper and
lower limits of the Mineral Resource.
|
The V1 and
V2 pegmatites are exposed in the V1/V2 pit and are two of the
largest pegmatites on ML 134. The V1 pegmatite is exposed in the
northeast of 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
assumptions, including treatment of extreme grade values,
domaining, interpolation parameters and maximum distance of
extrapolation from data points. If a computer assisted estimation
method was chosen, include a description of computer software and
parameters used.
The availability of check
estimates, previous estimates and/or mine production records and
whether the MRE takes appropriate account of such
data.
The assumptions made
regarding recovery of byproducts.
Estimation of deleterious
elements or other non-grade variables of economic significance
(e.g. sulphur for acid mine drainage
characterisation).
In the case of block model
interpolation, the block size in relation to the average sample
spacing and the search employed.
Any assumptions behind
modelling of selective mining units.
Any assumptions about
correlation between variables.
Description of how the
geological interpretation was used to control the resource
estimates.
|
An in-situ
MRE was undertaken for the two pegmatite bodies referred to as the
V1 and V2 pegmatites.
Raw data
were loaded and used to build the geological model; part of the
process included coding the drillholes by geology/lithology then
exporting those coded data from Datamine software to Isatis
software for geostatistical analyses. Once the data were loaded
into Isatis and prior to composting, the 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 data
statistics were compared to the raw data to confirm that the
compositing procedure generated reliable results and that residuals
were treated as follows:
x
If the analysed length of the last core at the end
of the line was smaller than 50% of the composite length, it was
ignored
x If the
analysed length of the last core was greater than 50% of the
composite length, it was kept as it is.
Correlation between all variables was low with no pair having
a correlation greater than 0.4.
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 process of validation,
the checking process used, the comparison of model data to
drillhole data, and use of reconciliation data if
available.
|
The
quality of the experimental variography is element dependent and
ranges from poor to moderate.
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 Li2O Mineral
Resources were classified as Inferred. Estimated grades for tin,
tantalum and Li2O 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, and the method
of determination of the moisture content.
|
Tonnages
have been estimated on a dry, in-situ basis with no allowance for
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 and internal
(or, if applicable, external) mining dilution. It is always
necessary as part of the process of determining reasonable
prospects for eventual economic extraction to consider potential
mining methods, but the assumptions made regarding mining methods
and parameters when estimating Mineral Resources may not always be
rigorous. Where this is the case, this should be reported with an
explanation of the basis of the mining assumptions
made.
|
It has
been assumed that the deposit is amenable to open cut mining
methods and are potentially economic to exploit to the depths
indicated by the pit shell optimisation exercise.
An in-situ
Mineral Resource model was generated using a block size of 20 m x
20 m x 10 m without dilution factors applied. Mining will be
undertaken by truck (80-tonne) and shovel.
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 NPVSTM 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
|
|
|
|
Mining
|
Waste
mining cost (fixed cost)
|
US$/t
|
1.3
|
RPEEE_parameters.xls
|
|
Ore mining
cost (fixed cost)
|
US$/t
|
4.3
|
RPEEE_parameters.xlsx
|
|
Mining
recovery
|
%
|
95
|
RPEEE_parameters.xlsx
|
|
Mining
dilution
|
%
|
5
|
RPEEE_parameters.xlsx
|
|
Rehabilitation
|
US$/t
|
0.07
|
|
|
Overall
slope angle
|
°
|
55
|
RPEEE_parameters.xlsx
|
Petalite
|
LI unit in
block model
|
ppm
|
-
|
|
|
Li
%
|
%
|
Li/10000
|
|
|
Li2O %
|
%
|
(Li
ppm/10000)*2.153
|
|
|
Petalite
concentrate price
|
US$/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$/conc
t
|
15,300
|
|
|
Royalty
|
%
|
3
|
|
|
Sn
processing recovery
|
%
|
80
|
|
|
Sn
concentrate grade
|
%
|
60
|
76%
SnO2 conc grade
|
|
Sn
processing cost
|
US$/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. It is always
necessary as part of the process of determining reasonable
prospects for eventual economic extraction to consider potential
metallurgical methods, but the assumptions regarding metallurgical
treatment processes and parameters made when reporting Mineral
Resources may not always be rigorous. Where this is the case, this
should be reported with an explanation of the basis of the
metallurgical assumptions made.
|
Historical
recoveries reported by ISCOR and internal Andrada testwork support
the recovery of 80% Sn and the production of a 60% Sn concentrate
which have been used to generate the pit shell from which Mineral
Resources have been reported. The resulting concentrates include up
to 1.5% Ta content which can be separated magnetically, although
the economic viability of doing this remains to be ascertained.
Lithium mineralogy, based on available xray 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 options. It is always
necessary as part of the process of determining reasonable
prospects for eventual economic extraction to consider the
potential environmental impacts of the mining and processing
operation. While at this stage the determination of potential
environmental impacts, 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.
|
ERM has
not undertaken a review of the environmental factors that may be
associated with the project and these will be covered in detail in
subsequent phases of study work. Andrada hold a valid Mining Permit
with contingent environmental responsibilities that will need to be
adhered to in order to advance the project.
|
|
Bulk
density
|
Whether assumed or
determined. If assumed, the basis for the assumptions. If
determined, the method used, whether wet or dry, the frequency of
the measurements, the nature, size and representativeness of the
samples.
The bulk density for bulk
material must have been measured by methods that adequately account
for void spaces (vugs, porosity, etc.), moisture and differences
between rock and alteration zones within the
deposit.
Discuss assumptions for bulk
density estimates used in the evaluation process of the different
materials.
|
Dry bulk
density has been based on specific gravity of samples, determined
by commercial pycnometric methods. This is considered appropriate
given the competent, crystalline nature of the pegmatite. For every
sample collected by Andrada, a SG was measured using the pycnometer
method which is considered equivalent to the dry bulk density. The
range of dry bulk densities for the pegmatites is low (2.55
t/m3 to 2.83 t/m3) with an average value of
2.65 t/m3. The average density value of 2.65 was used in
the block model.
|
|
Criteria
|
JORC Code
explanation
|
Commentary
|
|
Classification
|
The basis for the
classification of the Mineral Resources into varying confidence
categories.
Whether appropriate account
has been taken of all relevant factors (i.e. relative confidence in
tonnage/grade estimations, reliability of input data, confidence in
continuity of geology and metal values, quality, quantity and
distribution of the data).
Whether the result
appropriately reflects the Competent Person's view of the
deposit.
|
In the
first instance, classification was assigned based on geological
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 unity and as with most regression
analyses, unity means perfect correlation and the lower the value,
the poorer the estimate is. Another useful measure of estimation
confidence is the KE; it is a measure of the ratio of the
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 negative values means that the estimation
variance is equal to or greater than 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 in the MRE
using an approach or procedure deemed appropriate by the Competent
Person. For example, the application of statistical or
geostatistical procedures to quantify the relative accuracy of the
resource within stated confidence limits, or, if such an approach
is not deemed appropriate, a qualitative discussion of the factors
that could affect the relative accuracy and confidence of the
estimate.
|
As this is
an operating mine, reconciliation between the mined and modelled Sn
grade is reported to be within an acceptable range (±15%). No
reconciliation information for Li is available yet.
This is a
global estimate reported without the application of a cut-off grade
as the entire Mineral Resource is within the optimised pit shell.
Estimates 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
or local estimates, and, if
local, state the relevant tonnages, which should be relevant to
technical and economic evaluation. Documentation should include
assumptions made and the procedures used.
These statements of relative
accuracy and confidence of the estimate should be compared with
production data, where available.
|
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 parameters is largely a function of the
number of samples used and the semi-semi-variogram
models.
The sum of
positive weights was reviewed and by default the sum of the
negative weights. A small percentage of negative weights (< 2%)
is 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.
|
