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Dougou Extension (DX) Project drilling results and progress update
Kore Potash plc
(Incorporated in England and Wales)
Registration number 10933682
ASX share code: KP2
AIM share code: KP2
JSE share code:KP2
ISIN: GB00BYP2QJ94
(“Kore Potash” or the “Company”)
27 May 2021
Dougou Extension (DX) Project drilling results and progress update
Kore Potash plc, the potash development company with 97%-ownership of the Kola and Dougou
Extension (“DX”) Potash Projects in the Sintoukola Basin, Republic of Congo (“RoC”), is pleased to
announce an update on the DX Potash Solution Mining Project Definitive Feasibility Study (“DFS”) and
the recent drilling programme.
Highlights
• The drilling program for phase 1 of the DX DFS has been completed, and assay results received.
• Seven diamond drill holes were completed in the DFS phase 1 drilling program and assays sent
for geochemical testing.
• Analysis of the drill hole logs and assay results from the drilling campaign has:
o Confirmed the locations of the targeted Hanging wall and Top potash seams.
o Improved confidence in the distribution of sylvinite within the Top Seams (“TS”).
o Demonstrated that the sylvinite / carnallite boundary within the Hanging Wall Seam
(“HWS”) is structurally controlled and the sylvinite distribution is more complex than
modelled in the Pre-Feasibility Study.
o Identified areas containing carnallite that will be excluded and not considered for
extraction in future mine planning for the DX project.
o Indicated that further drill hole and seismic information may be required to have
confidence in the distribution of sylvinite in the HWS.
• Key technical studies and laboratory test work for Phase 1 of the DX DFS that are complete
include:
o Dissolution testwork to provide improved data for temperature brine-modelling.
o Laboratory testing of rock mechanics properties to assist in determination of cavern
stability, the possible extent of reservoir mining and expected subsidence over the
project life.
o Production well design to provide specifications for future capital cost estimating.
o Cavern blanket design parameters (to control cavern formation) to provide
specifications for future capital cost estimating.
• Work completed in Phase 1 of the DX DFS has been completed within the planned budget.
• Before proceeding further with the DX DFS, the Company plans to:
o Develop a new geological model for the DX deposit incorporating the results of the
recent drilling campaign.
o Determine using the new modelling whether further drill hole and seismic information
may be required to further improve confidence in the distribution of Sylvinite and
Carnallite within the DX Deposit.
• Work has commenced on the development of the new geological model and this work is
expected to be completed before the end of 2021.
Brad Sampson, CEO, commented: “The recent drilling campaign at our DX project has improved our
knowledge of the location of the sylvinite and carnallite potash mineralisation which was the main
objective for the drilling. This further data will be used to incorporate an updated geological model as
part of the DFS work we are undertaking for this shallow solution mining project. The update of the
DX geological model will happen in parallel with the ongoing capital optimisation and financing activity
for the development of the Kola project which is currently the Company’s main focus.”
Drilling results
The Top Seam Sylvinite (“TSS”) and the Hanging Wall Seam Sylvinite (“HWSS”) located within the Cycle
IX of the Salt Member were the key targeted potash seams for this drilling program.
The drilling of seven diamond drill holes (labelled DX_10 through DX_14, DX_15B and DX_16)
commenced in October 2020 and finished in February 2021. The laboratory assay of samples of core
from this drilling programme encountered some quality assurance issues that delayed transmission of
approved results to Kore until May 2021.
The positions of all holes are shown in Table 1, and Figure 1 illustrates the DX area and location of all
drill holes completed.
Table 1. Positions of drill holes DX_10 to DX_16. All holes were drilled vertically. Projection/datum:
WGS84 UTM zone 32S, using DGPS.
Easting Northing Elevation Depth
BHID (m) (m) (masl) (m)
DX_10 790763.9 9529746 57.914 438.86
DX_11 790206.9 9529432 57.453 417.12
DX_12 790388.2 9529947 53.712 422.85
DX_13 791192 9529212 64.359 454.72
DX_14 790366.2 9530309 52.873 379.54
DX_15B 790503.2 9528717 73.548 457.22
DX_16 790199 9528386 83.424 502.19
Figure 1: Map showing DX project area, relative to Pointe Noire and other Kore project areas
(available at www.korepotash.com)
Figure 2: Map showing DX DFS Phase 1 drilling area
(available at www.korepotash.com)
Figure 3: Map showing positions of all DX drill-holes, seismic lines and drilling status, respectively
(available at www.korepotash.com)
Core Logging
Recovery of core was excellent from all drill holes, and all core was logged immediately upon recovery
by a qualified field geologist and photographed. Upon completion of the drilling of each hole, detailed
downhole geophysical logging was undertaken.
Core sampling and lab analyses
A total of 431 samples of core from five drill holes were prepared and dispatched for analysis at SGS
Lakefield laboratory in Canada.
The assay results of targeted seams intersected in the five drill holes, and their corresponding
mineralogy were received in May 2021 and are provided in Table 2.
Summary of results of drilling, logging and assaying
• Two drill holes (DX_11 and DX_13) intersected sylvinite in both TSS & HWSS horizons. Within
drill hole DX_11, the results indicate leaching of the potassium has occurred, resulting in low-
grade sylvinite. Drill hole DX_13 intersected well-developed sylvinite in the Top Seams and
the Hangingwall Seam with high KCl grade.
• In three drill holes (DX_10, DX_12 and DX_15B) well developed sylvinite was intersected in
the Top Seams and sylvinite overlying carnallite or simply carnallite was intersected in the
underlying Hangingwall Seam. The presence of carnallite within the seams effectively excludes
that area from solution mining to recover sylvinite.
• In two drill holes (DX_14 and DX_16) sylvinite mineralisation was not intersected. Drill Hole
DX_14 intersected the Salt Member below Seam 2 of Cycle IX indicating that both the Top
Seam and Hanging Wall Seam were eroded away. Drill hole DX_16 was drilled to over 500m
depth and intersected carnallite in the upper portion of Cycle X indicating that Cycle IX and
the TS and HWS, which are geologically deeper than Cycle X will be composed of carnallite.
Table 2. Assays results for targeted seams intersected in DX_10, DX_11, DX_12, DX_13 and DX_15B.
From To Insoluble
Drill- Intersected Thickness
hole seams
depth depth
(m) KCl (%)* content Mg (%) Comments
(m) (m) %
Top Seam 5-9 381.45 391.94 10.49 24.68 0.140 0.088 TSS
Top Seam 6-8 381.85 388.09 6.24 30.00 0.142 0.088 TSS
DX_10
Hangingwall 401.99 404.02 2.03 64.01 0.470 0.056 HWSS
Seam 404.02 409.77 5.75 23.80 0.183 7.748 HWSC
TS completely
Top Seam 5-9 365.47 367.81 2.34 <0.1 <0.1 <0.01
leached out
TS completely
DX_11 Top Seam 6-8 0.00 0.00 0.00 0.00 0.000 0.000
leached out
Hangingwall HWS completely
378.56 381.42 2.86 <0.1 <0.1 <0.01
Seam leached out
Top Seam 5-6 378.10 382.01 3.91 25.19 0.112 0.038 TSS
Top Seam 7-9 0.00 0.00 0.00 0.00 0.000 0.000 Beds not present
DX_12
Hangingwall 388.55 390.69 2.14 57.11 0.057 0.092 HWSS
Seam 390.69 392.34 1.65 24.86 0.142 8.298 HWSC
Top Seam 5-9 402.92 411.17 8.25 24.51 0.094 0.052 TSS
Top Seam 6-8 404.13 408.13 4.00 32.18 0.111 0.050 TSS
DX_13
Hangingwall
420.08 424.09 4.01 58.98 0.067 0.018 HWSS
Seam
Top Seam 5-10 429.52 435.10 5.58 26.94 0.140 0.035 TSS
Top Seam 6-8 429.94 433.09 3.15 34.62 0.156 0.026 TSS
DX_15B Not
Hangingwall Assayed
440.10 446.49 6.39 HWSC
Seam all
Carnallitite
*Equivalent KCl, including KCl from both
Sylvinite and Carnallite.
Abbreviations for Table 2.
TSS- Top Seam Sylvinite
TSC- Top Seam Carnallite
HWSS- Hanging Wall Seam Sylvinite
HWSC- Hanging Wall Seam Carnallite
Technical Studies
The phase 1 work programme for the DX DFS included the completion of a number of technical studies.
All of these studies were designed to improve knowledge of some of the key design parameters for
the DX project.
These individual studies are complete and further studies will be required in the future prior to
restatement of the DX production target. The company has not planned to undertake these further
studies at this point in time.
The specific studies completed in this Phase 1 are:
• Dissolution testwork was done by Agapito Associates Incorporated (AAI). This testwork was
completed at 90 degree Celsius with solvent potassium chloride (KCl) concentrations
of170,180, 190 and 200 grams per litre (g/l). This testwork was undertaken to determine the
ultimate brine concentration when the dissolution rate is near zero, for the range of KCL
concentrations. The results of the test work provide inputs for temperature brine-modelling.
• Laboratory testing of rock mechanics properties of samples of diamond drill core covering the
upper portion of the anhydrite bed overlaying the salt sequence, through to the halite below
the HWS. Testing of uniaxial and triaxial compressive strength (UCS and TCS respectively) was
completed in the AAI rock mechanics laboratory in Grand Junction, Colorado and creep tests
were undertaken at Institut Fur Gebirgsmechanik GmbH (IfG) in Germany. Geomechanical test
results will enable modelling of cavern stability during mining, subsidence, and to assess the
possible extent of reservoir mining. Modelling aides in predicting ultimate subsidence over
the project life. These properties will be incorporated into the geomechanical modelling in a
future phase of work.
• Geomechanical modelling to evaluate cavern stability during mining has been undertaken on
a variety of cavern radii and pillar thicknesses to inform the future mine design.
• An investigation into the potential interaction between solution mining and known aquifers
has been completed. This exercise will help predict potential brine leakage and identify
leakage control options. These findings will be incorporated into the geomechanical modelling
in a future phase of work.
• AAI conducted cavern temperature modelling for the single-well cavern pattern. The
temperature modelling has included numerical evaluation of steady-state cavern
temperatures for more accurate prediction of production brine concentration. The cavern
temperature model will be coupled with the dissolution and geomechanical models for
production brine grade prediction in a future phase of work.
• Production well design based on the modelled heat exchange between the flow in the annulus
and tubing for single-well cavern solution mining has been completed and specifications
provided for future capital cost estimating.
• Cavern blanket design parameters (to control cavern formation) have been determined to
provide specifications for future capital cost estimating.
Conclusions from this phase of work and next steps for the DX Project
The information obtained from the diamond drilling programme has:
• Confirmed the locations of the targeted Hanging wall seam sylvinite and Top seam sylvinite.
• Improved confidence in the distribution of sylvinite within the Top Seams.
• Demonstrated that the sylvinite / carnallite boundary within the Hanging Wall Seam is
structurally controlled and the sylvinite distribution is more complex than modelled in the Pre-
Feasibility Study.
• Identified areas containing carnallite that will be excluded and not considered for extraction
in future DX project mine planning.
In addition, review of the drilling results indicates that further drill hole and seismic information may
be required to have confidence in the distribution of sylvinite in the HWS.
Before proceeding further with the DX DFS, the Company plans to:
• Develop a new geological model for the DX deposit incorporating the results of the recent
drilling campaign.
• Determine using the new modelling whether further drill hole and seismic information may
be required to further improve confidence in the distribution of Sylvinite and Carnallite within
the DX Deposit.
Work has commenced on the development of the new geological model and this work is expected to
be completed before the end of 2021.
Appendix A provides the JORC (2012 edition) CODE Table 1 checklist and assessment of reporting
criteria, sections 1 and 2.
This announcement has been approved for release by the Board.
ENDS
For further information, please visit www.korepotash.com or contact:
Kore Potash Tel: +27 (11) 469 9140
Brad Sampson - CEO
Tavistock Communications Tel: +44 (0) 20 7920 3150
Jos Simson
Edward Lee
Canaccord Genuity - Nomad and Broker Tel: +44 (0) 20 7523 4600
James Asensio
Henry Fitzgerald-O'Connor
Shore Capital - Joint Broker Tel: +44 (0) 20 7408 4050
Jerry Keen
Toby Gibbs
James Thomas
Questco Corporate Advisory – JSE Sponsor Tel: +27 (11) 011 9208
Mandy Ramsden
Competent Persons Statement:
All information in this report that relates to Exploration Results is based on information compiled by
Richard Baars, Associate Engineer of Agapito Associates Inc. Mr. Baars is a licensed professional mining
engineer in the state of Colorado, USA, and is a registered member (RM) of the Society of Mining,
Metallurgy and Exploration, Inc. (SME, Member 4276193), a Recognized Professional Organization’
(RPO) included in a list that is posted on the ASX website from time to time.
Mr. Baars has sufficient experience that is relevant to the style of mineralisation and type of Deposit
under consideration and to the activity he is undertaking to qualify as a Competent Person, as defined
in the 2012 Edition of the “Australasian Code for Reporting of Exploration Results, Mineral Resources
and Ore Reserves” (the JORC Code). Mr. Baars consents to the inclusion in this report of the matters
based on the information in the form and context in which it appears.
Mr. Baars is full time employee of Agapito Associates Inc. and is not associated or affiliated with Kore
Potash or any of its affiliates. Agapito Associates Inc will receive a fee for the preparation of the Report
in accordance with normal professional consulting practices. This fee is not contingent on the
conclusions of the Report and Agapito Associates Inc. Agapito Associates Inc does not have, at the
date of the Report, and has not had within the previous years, any shareholding in or other
relationship with Kore Potash or the Dougou Extension Potash Project and consequently considers
itself to be independent of Kore Potash.
APPENDIX A
JORC CODE Table 1 Checklist of Assessment and Reporting Criteria – sections 1-2
Section 1 Sampling Techniques and Data
(Criteria in this section apply to all succeeding sections.)
Section 1 - Sampling Techniques and Data
JORC Criteria JORC Explanation Commentary
1.1 SAMPLING TECHNIQUES • Nature and quality of sampling (e.g. cut channels, random chips, or • Sampling of Kore’s holes was carried out according to an industry standard
specific specialised industry standard measurement tools appropriate to operating procedure (SOP) beginning at the drill rig.
the minerals under investigation, such as down hole gamma sondes, or • Core drilling was used to provide core samples. Sample intervals were
handheld XRF instruments, etc.). These examples should not be taken as between 0.14 and 1.02 metres and sampled to lithological boundaries
limiting the broad meaning of sampling. where present. Minor lithological intervals (less than 10cm) were generally
• Include reference to measures taken to ensure sample representivity and included within a larger sample.
the appropriate calibration of any measurement tools or systems used. • In all cases, core was cut along a ‘center-line’ marked such that both
• Aspects of the determination of mineralisation that are Material to the halves are as close to identical as possible.
Public Report. In cases where ‘industry standard’ work has been done this • All were sampled as half-core and cut using an Almonte© core cutter
would be relatively simple (e.g. ‘reverse circulation drilling was used to without water, and blade and core holder cleaned between samples.
obtain 1 m samples from which 3 kg was pulverised to produce a 30 g Samples were individually bagged and sealed in boxes.
charge for fire assay’). In other cases, more explanation may be required, • At the laboratory, samples will be crushed to 90% passing 2 mm then riffle
such as where there is coarse gold that has inherent sampling problems. split to derive a 250 g sample for pulverizing to 85% passing 75 microns.
Unusual commodities or mineralisation types (e.g. submarine nodules) • Further discussion on sampling representivity is provided in section 1.5.
may warrant disclosure of detailed information. • Downhole geophysical data including gamma-ray data were collected and
provided a useful check on the depth and thickness of the potash intervals.
1.2. DRILLING TECHNIQUES • Drill type (e.g. core, reverse circulation, open-hole hammer, rotary air • Holes were drilled in two to three phases by rotary percussion through the
blast, auger, Bangka, sonic, etc.) and details (e.g. core diameter, triple or 'cover sequence' (Phase 1 with 12 ¼” -inch diameter, Phase 2 with 7 7/8” -
standard tube, depth of diamond tails, face-sampling bit or other type, inch diameter, and where Phase 3 with 5 ½” or 5 7/8” ) stopping 3-5 m into
whether core is oriented and if so, by what method, etc.). in the Anhydrite Member and cased and grouted to this depth. Holes were
then advanced using diamond coring with the use of tri-salt (K, Na, Mg)
mud to avoid dissolution and ensure acceptable recovery. All holes were
drilled as close to vertically as possible.
1.3. DRILL SAMPLE • Method of recording and assessing core and chip sample recoveries and • Core recovery was recorded for all cored sections of Kore’s holes by
RECOVERY results assessed. recording the drilling advance against the length of core recovered.
• Measures taken to maximise sample recovery and ensure representative Recovery is between 95 and 100% for the potash intervals. A full-time mud
nature of the samples. engineer was recruited to maintain drilling mud chemistry and physical
• Whether a relationship exists between sample recovery and grade and properties.
whether sample bias may have occurred due to preferential loss/gain of • Core was wrapped in cellophane sheet soon after it is removed from the
fine/coarse material. core barrel, to avoid dissolution in the atmosphere, and was then
transported at the end of each shift to a de-humidified core storage room
where it is stored permanently.
• There are no concerns relating to bias due to recovery or due to
preferential loss of certain size fractions; the sylvinite and halite are of
similar grainsize and hardness.
1.4. LOGGING • Whether core and chip samples have been geologically and • The entire length of Kore’s holes was logged geologically, from rotary chips
geotechnically logged to a level of detail to support appropriate Mineral in the ‘cover sequence’ and core in the evaporite. Logging is qualitative
Resource estimation, mining studies and metallurgical studies. and supported by quantitative downhole geophysical data including
• Whether logging is qualitative or quantitative in nature. Core (or costean, gamma and acoustic televiewer images, which provide a useful check on
channel, etc.) photography. the conventional core logging.
• The total length and percentage of the relevant intersections logged. • Recognition of the potash seams is straightforward and made with
confidence.
• Core was photographed to provide an additional reference and record.
1.5 SUB-SAMPLING • If core, whether cut or sawn and whether quarter, half or all core taken. • Kore’s samples were sawn as described above, into two halves. One half
TECHNIQUES AND SAMPLE • If non-core, whether riffled, tube sampled, rotary split, etc. and whether was retained at site as a record, and one half sent in a batch of samples to
PREPARATION sampled wet or dry. the laboratory.
• For all sample types, the nature, quality and appropriateness of the • Care was taken to orient the core before cutting so that the retained and
sample preparation technique. submitted halves were as similar as possible.
• Quality control procedures adopted for all sub-sampling stages to • For at least 1 in 20 samples both halves were submitted, as two separate
maximise representivity of samples. samples – an original and (field) duplicate sample.
• 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.
1.6 QUALITY OF ASSAY • The nature, quality and appropriateness of the assaying and laboratory • Analyses were carried out at SGS Lakefield in Canada. Water soluble K,
DATA AND LABORATORY procedures used and whether the technique is considered partial or total. Na, Ca, Mg and S to be determined by ICP-AES. Insolubles were
TESTS • For geophysical tools, spectrometers, handheld XRF instruments, etc., the determined by filtration of the residual solution and slurry membrane filter,
parameters used in determining the analysis including instrument make washing to remove residual salts, drying, and weighing.
and model, reading times, calibrations factors applied and their derivation, • A full quality control and assurance (QA/QC) program was implemented by
etc. Kore Potash, to assess repeatability of the sampling procedure and the
• Nature of quality control procedures adopted (e.g. standards, blanks, precision of the laboratory sample preparation and the accuracy of
duplicates, external laboratory checks) and whether acceptable levels of analyses. SGS Labs carries out its own internal QA/QC program as per
accuracy (i.e. lack of bias) and precision have been established. labs procedure.
• This comprised the insertion of blanks, duplicates, certified reference
materials and internal (non-certified) reference material. QA/QC samples
make up 13% of the total number of samples submitted, which is in line
with industry best-practices. Any non-conforming samples were re-tested
by laboratory while remaining samples were under Lab custody.
1.7. VERIFICATION OF • The verification of significant intersections by either independent or • Sampling and other drilling data is captured into MS Excel, then imported
SAMPLING AND ASSAYING alternative company personnel. along with assay data into an MS Access database. On import, checks on
• The use of twinned holes. data are always made for errors. All original data is archived in original
• Documentation of primary data, data entry procedures, data verification, format from lab.
data storage (physical and electronic) protocols. • Remaining samples, pulps, and hard copies of lab reports will be shipped
• Discuss any adjustment to assay data. from lab to a secure company storage facility for record.
• All mineralised intervals used for the MRE are checked and re-checked
and compared against lithology and gamma data, which provide a further
check of grade and thickness. No adjustments were made to the assay
data. All conversions were within statistical tolerances.
1.8. LOCATION OF DATA • Accuracy and quality of surveys used to locate drill holes (collar and • At completion of drilling, DX_10 to DX_16 was surveyed using a DGPS for
POINTS down-hole surveys), trenches, mine workings and other locations used in location and elevation accuracy. All holes were drilled as close as possible
Mineral Resource estimation. to seismic survey stations which have been surveyed prior to drilling by a
• Specification of the grid system used. surveyor using a DGPS.
• Quality and adequacy of topographic control. • All mapping including seismic and drill-hole positions are given in WGS 84
UTM Zone 32S (32732). (Table in the announcement).
1.9. DATA SPACING AND • Data spacing for reporting of Exploration Results. • Figure 2 in the announcement shows the location of the drill-holes and
DISTRIBUTION • Whether the data spacing and distribution is sufficient to establish the current seismic lines.
degree of geological and grade continuity appropriate for the Mineral • Additional drilling is recommended at this time to expand the MRE.
Resource and Ore Reserve estimation procedure(s) and classifications
applied.
• Whether sample compositing has been applied.
1.10. ORIENTATION OF DATA • Whether the orientation of sampling achieves unbiased sampling of • Intersections have a sufficiently low angle of dip and drill-holes were drilled
IN RELATION TO possible structures and the extent to which this is known, considering the vertically; a correction of thickness for apparent thickness was not deemed
GEOLOGICAL STRUCTURE deposit type. necessary. Drill-hole inclination was surveyed to check verticality, it is
• If the relationship between the drilling orientation and the orientation of close to -90° for the potash intersections.
key mineralised structures is considered to have introduced a sampling
bias, this should be assessed and reported if material.
1.11. SAMPLE SECURITY • The measures taken to ensure sample security. • The chain of custody of samples was secure. At the rig, the core was
under full supervision of a Company geologist. At the end of each drilling
shift, the core was transported by Kore Potash staff to a secure site where
it is stored within a locked room.
• Sampling was carried out under the observation of Company staff; packed
samples were transported directly from the site by Company staff to DHL
couriers in Pointe Noire, 3 hours away. From there DHL airfreighted all
samples to the laboratory in Canada. Samples were weighed before
sending and on receipt of the results weights will be compared with those
reported by the lab.
1.12. AUDITS OR REVIEWS • The results of any audits or reviews of sampling techniques and data. • Kore’s sampling procedure has been reviewed on several occasions by
external parties, for the MRE for the Kola, Dougou and DX Deposits.
• The supporting data has been checked by the external CP, with inspection
of logging sheets and laboratory analysis certificates.
Section 2 Reporting of Exploration Results
(Criteria listed in the preceding section also apply to this section.)
Section 2 - Reporting of Exploration Results
JORC Criteria JORC Explanation Commentary
2.1 MINERAL TENEMENT • Type, reference name/number, location and ownership including • The DX Deposit is entirely within the Dougou Mining Licence which is held
AND LAND TENURE STATUS agreements or material issues with third parties such as joint ventures, 100% under the local company Dougou Mining SARL which is in turn held
partnerships, overriding royalties, native title interests, historical sites, 100% by Sintoukola Potash SA RoC, of which Kore Potash holds a 97%
wilderness or national park and environmental settings. share. The Permit is valid for 25 years from 9th May 2017.
• The security of the tenure held at the time of reporting along with any • There are no impediments on the security of tenure.
known impediments to obtaining a license to operate in the area.
2.2 EXPLORATION DONE BY • Acknowledgment and appraisal of exploration by other parties. • Potash exploration was carried out in the area in the 1960's by Mines
OTHER PARTIES domaniales de Potasse d’ Alsace S.A. High quality geological logs are
available for these holes. Hole K52 intersected HWSS and was the initial
reason for Kore’s interest in the area, beginning with the twin-hole drilling of
ED_01 in 2012 to ‘twin’ historic hole K52.
• Seismic data was acquired by oil exploration companies British Petroleum
Congo and Chevron during the 1980’s and by Morel et Prom in 2006.
2.3. GEOLOGY Deposit type, geological setting and style of mineralisation. • The potash seams are hosted by the 400-500 m thick Loeme Evaporite
formation of sedimentary evaporite rocks. These are within the Congo Basin
which extends from the Cabinda enclave of Angola to southern Gabon from
approximately 50 km inland, extending some 200-300 km offshore. The
evaporites were deposited during the Aptian epoch of the Lower Cretaceous,
between 125 and 112 million years ago.
• The evaporites formed by cyclic evaporation of marine-sourced brines which
were fed by seepage into an extensive subsiding basin, each cycle generally
following the expected brine evolution and resultant mineral precipitation
model: dolomite then gypsum then halite then the bitterns of Mg and K as
chlorides. To precipitate the thick potash beds the system experienced
prolonged periods within a range of high salinity of brine concentration.
• Sylvinite is a rock comprised predominantly of sylvite and halite. The term
‘rock-salt’ is used to refer to a rock comprising of halite without appreciable
potash. Sylvinite is typically reddish or pinkish in colour whereas carnallite is
coarse crystalline and typically orange to reddish orange.
• At DX the evaporite stratigraphy is slightly elevated and thinned relating to the
presence of an underlying horst block forming a paleo-topographic high in the
pre- and syn-rift rocks below the evaporite. This feature is referred to as the
‘Yangala High’ and was an important ‘large-scale’ control on the development
of sylvinite in the DX area.
• 11 evaporite cycles have been recognised, of which most are preserved at
DX. The ‘Top Seam’ (TS) and ‘Hangingwall Seam’ (HWS) potash seams are
within the mid to upper part of cycle 9. Where sylvinite these are referred to as
the TSS and HWSS and where carnallite they are referred to as TSC and
HWSC.
• The TSS is made up of several narrow high grade sylvinite layers with barren
rock-salt layers between them. The individual layers within the TSS are
numbered 5 to 9 from lowest to uppermost.
• Capping the salt dominated part of the evaporite (Salt Member or ‘Salt’) is a
low permeability layer of anhydrite, gypsum and clay (referred to as the
‘Anhydrite Member’) between 10 and 16 m thick in drill-holes to date. It is at a
depth of between 290 and approximately 520 m at DX.
• The Anhydrite Member is covered by a thick sequence of dolomitic rocks and
clastic sediments of Cretaceous age (Albian) to recent.
• The potash seams were originally deposited as carnallite but at DX have been
replaced in some areas by sylvinite, by a process of non-destructive leaching
of Mg, OH and some NaCl from carnallite, converting it to sylvite. The
conversion from carnallite to sylvinite leads to a significant reduction of the
seam thickness and a concomitant increase of grade. This process has taken
place preferentially over the Yangala High, initiating from the top of the Salt
Member. The process advanced on a laterally extensive ‘front’ and was
efficient; when converted to sylvinite, almost no residual carnallite remains
within the sylvinite.
• The zone within which carnallite seams have been converted to sylvinite is
termed the SYLVINITE zone. This laterally extensive zone starts a short
distance below the SALT_R and extends down to typically 40-50 m below this
contact, but rarely as much as 80 m. If the base of the SYLVINITE zone is
part-way through the potash seam, un-replaced carnallite occurs immediately
below the sylvinite part. In these situations, the contact between the sylvinite
and carnallite is abrupt and easily identified in core.
• In the upper 5-30 m of the Salt Member, the sylvinite may be further ‘leached’,
leaving pale reddish coloured halite with little to no KCl, referred to as ‘ghost’
seam and generally still identifiable for lateral correlation purposes. The zone
within which the sylvinite is leached is termed the LEACH zone.
• With reference to the above features, the main control on the distribution of
sylvinite at DX is the position of the seams (in vertical sense) relative to the
SYLVINITE zone; if the seam is above or below this zone they are ‘ghost’
(halite) or carnallite respectively.
2.4. DRILL HOLE • A summary of all information material to the understanding of the • The new borehole collar positions of the holes are provided in the
INFORMATION exploration results including a tabulation of the following information for all announcement, along with the final depth.
Material drill holes: • Holes were drilled vertically, at the depth of the intersections the hole dip was
• easting and northing of the drill hole collar greater than -88°.
• elevation or RL (Reduced Level – elevation above sea level in • Positions of the holes in relation to other holes are shown in the map in the
metres) of the drill hole collar announcement.
• dip and azimuth of the hole
• down hole length and interception depth
• 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.
2.5 DATA AGGREGATION • In reporting Exploration Results, weighting averaging techniques, • For the calculation of the grade over the full thickness of the seams, the
METHODS maximum and/or minimum grade truncations (e.g. cutting of high grades) standard length-weighted average method was used to combine results of
and cut-off grades are usually Material and should be stated. each sample.
• Where aggregate intercepts incorporate short lengths of high-grade results • No selective cutting of high or low-grade material was carried out.
and longer lengths of low-grade results, the procedure used for such • No metal equivalents were calculated.
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.
2.6 RELATIONSHIP • These relationships are particularly important in the reporting of • The sylvinite layers have sufficiently low degree of dip, and drill-holes are
BETWEEN MINERALISATION Exploration Results. close enough to vertical that a correction of intersected thickness was not
WIDTHS AND INTERCEPT • If the geometry of the mineralisation with respect to the drill hole angle is deemed necessary; the intersections are considered the ‘true thickness’.
LENGTHS known, its nature should be reported.
• If it is not known and only the down hole lengths are reported, there should
be a clear statement to this effect (e.g. ‘down hole length, true width not
known’).
2.7 DIAGRAMS • Appropriate maps and sections (with scales) and tabulations of intercepts • A map and tables are provided in the announcement.
should be included for any significant discovery being reported These
should include, but not be limited to a plan view of drill hole collar locations
and appropriate sectional views.
2.8 BALANCED REPORTING • Where comprehensive reporting of all Exploration Results is not • Seams of sylvinite intersections in all new holes are reported in Table 2 of the
practicable, representative reporting of both low and high grades and/or announcement.
widths should be practiced avoiding misleading reporting of Exploration
Results.
2.9 OTHER SUBSTANTIVE • Other exploration data, if meaningful and material, should be reported • DX_15B is named such as the first attempt to drill this hole failed. Drilling
EXPLORATION DATA including (but not limited to): geological observations; geophysical survey DX_15B was completed less than 5 meters away from the same location.
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.
2.10 FURTHER WORK • The nature and scale of planned further work (e.g. tests for lateral • At end of resource drilling, the completion and reporting of the updated
extensions or depth extensions or large-scale step-out drilling). Mineral Resource Estimate for DX is the next step.
• Diagrams clearly highlighting the areas of possible extensions, including
the main geological interpretations and future drilling areas, provided this
information is not commercially sensitive.
Date: 27-05-2021 08:00:00
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