Perseus Mining Limited (ASX/TSX: PRU) has updated its Life of Mine
Plan (“
LOMP”) for its Sissingué Gold Mine
(“
SGM”) and satellite deposits, Fimbiasso and
Bagoé, in Côte d’Ivoire (collectively
“
Sissingué”).
HIGHLIGHTS
- The mine life for
Sissingué has been extended to March 2026 with potential for
further extension by processing low grade ore stockpiles.
- Average annual gold
production is currently forecast at 72,000 ounces at an average
all-in site cost (ASIC) of US$1,261 per ounce.
- Updated Mineral
Resources are estimated at 7.2 million tonnes grading 1.7 g/t gold
containing 394,000 ounces of gold at December 31,
2021.
- Proved and Probable
Ore Reserves1 total 5.0 million tonnes of ore grading 1.8g/t gold
and containing 282,000 ounces of gold with ore drawn from pits at
Sissingué, Fimbiasso and Bagoé deposits.
- Key Sissingué LOMP2
parameters include:
KEY PARAMETERS |
UNITS |
UPDATEDLIFE OF MINE PLAN |
ANNUAL AVERAGEFY2023 –
FY2025 |
Total Ore + waste mined |
Mt |
24.1 |
7.4 |
Strip ratio |
t:t |
4.6:1 |
4.4:1 |
Ore processed |
Mt |
5.5 |
1.5 |
Head grade |
g/t gold |
1.6 |
1.7 |
Gold recovery rate |
% |
91.2 |
91.4 |
Gold production |
‘000 ozs |
252 |
72 |
|
|
|
|
Production costs |
US$/oz |
1,164 |
1,173 |
Royalty1 |
US$/oz |
63 |
63 |
Sustaining capital |
US$/oz |
25 |
25 |
Average All-in site costs |
US$/oz |
1,253 |
1,261 |
Notes:
-
Assumes a gold price of US$1,500 per ounce for Ore Reserve and
royalty calculations.
-
LOMP commences on July 1, 2022.
Perseus’s Managing Director and CEO Jeff Quartermaine
said:
“The Sissingué Gold Mine has been an important part of Perseus’s
geopolitically diversified asset portfolio since commencing
commercial production in 2018 with an estimated 4.5-year mine life.
Since then, the mine has consistently produced gold in excess of
forecasts and importantly, generated significant amounts of free
cashflow. This updated LOMP incorporates the processing of ore from
satellite deposits at Fimbiasso and Bagoé as well as the Sissingué
Gold Mine, and results in the life of the Sissingué operation being
extended out till at least March 2026 which enables Perseus to
continue generating material benefits for all of our stakeholders,
including the residents of our host communities at Fimbiasso and
Bagoé.”
Overview of Sissingué
Sissingué is located in northern Cote d’Ivoire in the West
African Craton where gold is mined in Paleoproterozoic (Birimian)
rocks of the southern extension of the Syama Greenstone Belt and
the western margin of the Senoufo Greenstone Belt. Gold deposits at
Sissingué are orogenic, greenstone hosted.
The SGM main pit mineralisation is structurally controlled and
mainly hosted within a granitic stock associated with a network of
quartz-carbonate veins and veinlets with associated pyrite and
arsenopyrite dissemination. Gold-bearing veins have a dominant NNW
to NS trend and are steeply dipping. Disseminated mineralisation is
also located in the alternation envelops of the mineralised quartz
veins.
SGM commenced commercial gold production at the end of March
2018 and by 30 June 2022 approximately 367,500 ounces of gold are
forecast to have been produced at the mine. The sources of ore to
be processed at Sissingué during the remaining 3.7 years of mine
life, as currently defined, are SGM, Fimbiasso and Bagoé deposits.
Each deposit consists of multiple pits and the ore feed will be
supplemented with stockpiles at SGM as detailed in Table
3. To ensure the mill is run at full capacity in the last
seven months of mine life, reducing processing and general
administration (G&A) unit rate costs, stockpiled mineralised
waste will be used to supplement ore feed. Ore from Fimbiasso and
Bagoé will be stockpiled temporarily on site then transported to
Sissingué for process plant feed as per milling schedule. Waste
material will be taken to the waste dump located near the pits.
Tailings from the process plant will be stored in a single, plastic
high-density polyethylene (HDPE) lined, tailings storage facility
located near the Sissingué process plant.
Many of Sissingué’s operational workforce live in the
communities located near the existing mine and processing facility,
and the satellite deposits. An on-site camp has been constructed at
SGM to accommodate members of the workforce who are not local
residents.
Figure 1 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/5849bbd8-5a71-4ea5-b894-1b15d5df0dda
Figure 2 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/a82240f2-5b70-4f8f-8d4a-a921536cfd51
Figure 3 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/2a80cbe4-6337-46ba-a22f-40b927965153
Figure 4 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/bc888168-89f7-4939-b629-b8008ff7f6c3
MINERAL RESOURCES AND ORE RESERVES SUMMARY
For a comprehensive description of SGM Mineral Resources and Ore
Reserves estimates, refer to the JORC tables included in
Appendix 1, and to the news release titled
“Perseus Mining Updates Mineral Resources and Ore Reserves” dated
26 August 2020 for all reference to the Fimbiasso Deposits and to
the news release titled “Perseus Mining Updates Mineral Resources
and Ore Reserves” dated 24 August 2021 for the Bagoé Deposits.
Table 1, 2 and 3 below summarise
the currently estimated Mineral Resources and Ore Reserves at
Sissingué.
Table 1: Sissingué Measured and Indicated Mineral
Resources – 31 December 2021 1,2
PROJECT |
DEPOSIT TYPE |
MEASURED RESOURCES |
INDICATED RESOURCES |
MEASURED + INDICATED RESOURCES |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
Sissingué 3,4,5 |
Open Pit |
1.2 |
1.4 |
50 |
1.3 |
1.4 |
56 |
2.4 |
1.4 |
107 |
Fimbiasso 6,7 |
Open Pit |
1.7 |
1.7 |
95 |
0.4 |
1.8 |
23 |
2.1 |
1.7 |
118 |
Bagoé 8,9 |
Open Pit |
0.7 |
2.2 |
53 |
1.0 |
2.3 |
73 |
1.7 |
2.3 |
126 |
Sub Total |
3.6 |
1.7 |
198 |
2.7 |
1.8 |
152 |
6.2 |
1.8 |
351 |
Stockpiles |
|
0.7 |
1.3 |
30 |
- |
- |
- |
0.7 |
1.3 |
30 |
Total |
4.3 |
1.6 |
227 |
2.7 |
1.8 |
152 |
7.0 |
1.7 |
379 |
Table 2: Sissingué Inferred Mineral Resources – 31
December 2021 2
PROJECT |
DEPOSIT TYPE |
INFERRED RESOURCES |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
Sissingué 3,4,5 |
Open Pit |
0.1 |
1.1 |
2 |
Fimbiasso 6,7 |
Open Pit |
0.1 |
1.8 |
6 |
Bagoé 8,9 |
Open Pit |
0.1 |
2.2 |
6 |
Sub Total |
0.3 |
1.5 |
14 |
Stockpiles |
|
- |
- |
- |
Total |
0.3 |
1.8 |
15 |
Notes:
1. Measured and Indicated Mineral
Resources are inclusive of Ore
Reserves. 2. Rounding of numbers to
appropriate precisions may have resulted in apparent
inconsistencies. 3. Based on February 2022
Mineral Resource model constrained to US$1,800/oz pit
shell. 4. Depleted to 31 December 2021 mining
surface. 5. 0.6g/t gold cut-off applied to in
situ material. 6. Based on March 2020 Mineral
Resource models constrained to US$1,800/oz pit
shells. 7. 0.8g/t gold cut-off
applied. 8. Based on May 2021 Mineral
Resource models constrained to US$1,800/oz pit
shells. 9. 0.8g/t gold cut-off applied to
oxide, 1g/t applied to transition, 1.2g/t applied to fresh
(Veronique deposit only).
Table 3: Proved and Probable Ore Reserves
as at 31 December 2021 5,
7
DEPOSIT |
DEPOSIT TYPE |
PROVED |
PROBABLE |
PROVED + PROBABLE |
QuantityMt |
Gradeg/t gold |
Gold‘000 oz |
QuantityMt |
Gradeg/t gold |
Gold‘000 oz |
QuantityMt |
Gradeg/t gold |
Gold‘000 oz |
Sissingué1,2,3,4 |
Open Pit |
1.0 |
1.3 |
40 |
0.9 |
1.3 |
37 |
1.9 |
1.3 |
78 |
Fimbiasso2,4 |
Open Pit |
1.1 |
2.0 |
70 |
0.2 |
2.2 |
13 |
1.3 |
2.0 |
83 |
Bagoé2,3,4 |
Open Pit |
0.5 |
2.6 |
40 |
0.6 |
2.6 |
51 |
1.1 |
2.6 |
91 |
Sub Total |
2.6 |
1.8 |
150 |
1.7 |
1.9 |
101 |
4.3 |
1.8 |
251 |
Stockpiles6 |
|
0.7 |
1.3 |
30 |
- |
- |
- |
0.7 |
1.3 |
30 |
Total |
3.3 |
1.7 |
181 |
1.7 |
1.9 |
101 |
5.0 |
1.8 |
282 |
Notes:1 Depleted to 31
December 2021 mining surface. 2 Based on February 2022
Mineral Resource model constrained to US$1,800/oz pit shell and
depleted to 31 December 2021 mining surface. 3 Based on
February 2022 Ore Reserve estimation. 4 Variable gold
grade cut-off for each material type, ranging from 0.40 g/t to 1.00
g/t at Sissingué deposits, from 0.80 g/t to 1.50 g/t at Fimbiasso
deposits and from 1.00 g/t to 3.00 g/t at Bagoé
deposits. 5 Inferred Mineral Resource is considered as
waste.6 Based on EOM December 2021 stockpile balance
report. 7 Rounding of numbers may result in apparent
mathematical inconsistencies.
LIFE OF MINE PLAN
Based on detailed mining and processing schedules recently
prepared as part of the life of mine planning process, the key
forecast operating parameters for Sissingué are summarised in
Table 4. To illustrate the changes to the
FY23 LOMP from the previous FY22 LOMP published in August 2021,
equivalent data is tabulated below. It should be noted that the
FY23 LOMP commences 1 July 2022 and accounts for actual depletion
of Ore Reserves between July 2021 to December 2021 and forecast
depletion between 1 January 2022 and 30 June 2022.
Mining cost estimates in the updated LOMP are based on projected
costs using the current contract with mining contractors, SFTP, who
have been conducting mining activities on site since mining
operations started. SFTP is expected to perform the full mining,
drilling and grade control service required at Sissingué. Explosive
costs are based on the projection of current contract prices
provided by contractor, Maxam, a leading
explosives manufacturer and distributor.
Gold recovery rates and processing costs are based on actual
results achieved in the last 12 months and combined with forward
projections based on a comprehensive metallurgical test work
program for areas with no experiential data. Processing costs
include costs associated with all consumables including
maintenance, electricity, fuel, labour, and other processing
overheads.
G&A and other costs are based on actuals and budget
projections. G&A operating costs include all labour costs,
Abidjan regional office costs, HR administration costs as well as
all costs associated with the management of the environment,
OH&S, security, government and community relations, general
administration including insurances and other contracts.
Sustaining capital costs include stage lifting of the tailings
storage facility (TSF), closure costs, progressive clearing,
contractor demobilisation, and plant modifications. The total
estimate of sustaining capital is US$7.6M million which over the
current life of mine equates to US$30/oz of gold produced.
Sustaining capital does not include any capital costs estimated for
the delineation of additional Mineral Reserves and Ore Reserves or
the establishment of new open pit or underground mining operations.
Any such developments will be regarded as development capital and
disclosed accordingly.
Table 4: Overview Key
Parameters4
|
UNITS |
FY23 LOMP |
TotalFY23-26 |
Annual AverageFY23-25 |
Mining |
|
|
|
Total ore + waste mined |
Mt |
24.11 |
7.4 |
Waste mined |
Mt |
19.81 |
6.0 |
Ore mined |
Mt |
4.31 |
1.4 |
Mined grade |
g/t gold |
1.81 |
1.7 |
Strip ratio |
t:t |
4.6:11 |
4.4:1 |
Processing |
|
|
|
Quantity ore processed |
Mt |
5.5 |
1.5 |
Head grade processed |
g/t gold |
1.6 |
1.7 |
Contained gold |
‘000ozs |
277 |
79 |
Gold recovery rate |
% |
91.2 |
91.4 |
Gold production |
‘000ozs |
252 |
72 |
Operating Costs2 |
|
|
|
Average mining costs |
US$/t mined |
5.822 |
5.96 |
Average processing costs |
US$/t processed |
15.96 |
16.47 |
Average general & administration costs |
US$/t processed |
12.02 |
12.11 |
Production costs |
US$/oz |
1,164 |
1,173 |
Royalty3 |
US$/oz |
63 |
63 |
Sustaining capital |
US$/oz |
25 |
25 |
All-in site costs |
US$/oz |
1,253 |
1,261 |
Notes:
1 Includes all ore and waste mined ex-pit
but excludes rehandle movement.
2 Excludes pre-strip costs that have been
capitalised.
3 Assumes a gold price of US$1,500/oz for
Ore Reserve and Royalty calculations, and US$1,250/oz for the
DFS.
4 LOMP commences 1 July 2022.
MINING AND PROCESSING SCHEDULES
Based on the estimated Ore Reserves summarised in Table 2:
Sissingué Inferred Mineral Resources – 31 December 20212
PROJECT |
DEPOSIT TYPE |
INFERRED RESOURCES |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
Sissingué 3,4,5 |
Open Pit |
0.1 |
1.1 |
2 |
Fimbiasso 6,7 |
Open Pit |
0.1 |
1.8 |
6 |
Bagoé 8,9 |
Open Pit |
0.1 |
2.2 |
6 |
Sub Total |
0.3 |
1.5 |
14 |
Stockpiles |
|
- |
- |
- |
Total |
0.3 |
1.8 |
15 |
Notes:
10. Measured and Indicated Mineral
Resources are inclusive of Ore
Reserves. 11. Rounding of numbers to
appropriate precisions may have resulted in apparent
inconsistencies. 12. Based on February 2022
Mineral Resource model constrained to US$1,800/oz pit
shell. 13. Depleted to 31 December 2021
mining surface. 14. 0.6g/t gold cut-off
applied to in situ material. 15. Based on
March 2020 Mineral Resource models constrained to US$1,800/oz pit
shells. 16. 0.8g/t gold cut-off
applied. 17. Based on May 2021 Mineral
Resource models constrained to US$1,800/oz pit
shells. 18. 0.8g/t gold cut-off applied to
oxide, 1g/t applied to transition, 1.2g/t applied to fresh
(Veronique deposit only).
, the mining production profile for Sissingué is forecast to be
as shown in Error! Reference source not found.
below. No Inferred Mineral Resources have been included as mill
feed in the updated LOMP.
Ore and waste will be mined from all Sissingué pits. Ore from
the Fimbiasso and Bagoé deposits will be stockpiled temporarily on
their respective sites then transported to SGM for processing as
per the mill feed schedule. Mill feed will be complimented with the
remaining ore stockpiles at Sissingué, with additional feed
supplement coming from mineralised waste material to ensure the
mill runs full capacity in the final seven months of mine life,
minimising the processing and G&A unit rate costs.
Mining is currently expected to be complete within four years of
operation from 1 July 2022. Mining will start at SGM and Fimbiasso
deposits in the first 18 months, the majority of ore feed will come
from Fimbiasso. At this time mining at SGM will be mostly from
satellite pits and waste stripping of the main pit, during which
time mining will be accelerated at the Fimbiasso deposit. Current
ore stockpiles will supplement mill feed as required. After mining
at Fimbiasso is complete, Bagoé mining is scheduled to start
following equipment relocation. Mining of the SGM deposit will
continue while the Bagoé deposit is being mined. In this period,
mining at SGM Main pit will be sufficiently advanced to mine
high-grade ore and complement lower feed grade ore from Bagoé. This
will result in higher gold production in FY25 compared to previous
years.
Figure 5 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/ff525f27-2fde-4fab-bde8-9293447fb844
Gold production in FY23 will mainly be derived from ore sourced
from Fimbiasso deposit, oxide ore from SGM satellite deposits and
existing stockpiles at SGM. Meanwhile, the pre-strip in the SGM
main pit will be undertaken to access the ore zone. Pre-stripping
at SGM main pit is expected to take 18 months before access into
the main ore zone is achieved.
In FY24, mining in Fimbiasso will be completed in the first half
of the year and will be replaced by Bagoé deposit as the main ore
source. By second half of FY24, the main ore zone in the SGM main
pit will be exposed. Stockpiled material will sustain mill feed at
full capacity.
The highest production year in the LOMP is FY25. In this period,
high grade ore will be mined from both the SGM main pit and the
Bagoé deposit. Ore from Bagoé will provide the main source of
high-grade mill feed ore. Mining at the SGM main pit will be
completed by the third quarter of FY25, requiring ore from Bagoé
deposit to be supplemented with remaining stockpiles available at
SGM during the fourth quarter.
Based on the LOM schedule, mining and processing at SGM will be
completed in FY26. Mining will be finished in February 2026 and
processing will be completed the following month, March 2026. In
this period the mill feed will be supplied from Bagoé deposit
supplemented with stockpiled mineralised waste. The use of
mineralised waste will enable the mill to operate at full capacity,
resulting in lower unit processing costs and G&A. By the end of
March 2026, approximately 650,000 tonnes of mineralised waste
stockpiles will remain. This material may be processed at a later
date subject to it being economically viable.
The processing rate is forecast to average 1.4 million tonnes
per year over the 3.7 years of mine life. The processing rate in
this LOM has been increased from the previous LOM from 220tpoh to
260tpoh and is based on experiential knowledge and current milling
rates experienced at SGM.
The forecast average gold production for the remaining mine from
1 July 2022, is estimated at approximately 72,000 ounces at an
average head grade of 1.7g/t and an average metallurgical recovery
of 91.4%. A total of 252,000 ounces of gold are forecast to be
recovered over the life of operation.
Figure 6 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/b42f50db-eefc-426c-bc2c-b0a706db730e
This announcement was approved for release by Perseus
Mining Limited’s Managing Director and CEO, Jeff
Quartermaine.
Competent Person Statement:
All production targets referred to in this
report are underpinned by estimated Ore Reserves which have been
prepared by competent persons in accordance with the requirements
of the JORC Code.
The information in this report that relates to
Mineral Resources for Sissingué is based on information compiled by
Ms Christine Shore, a Competent Person who is a Fellow of The
Australian Institute of Mining and Metallurgy. Ms Shore is a
full-time employee of Perseus Mining, and she has no economic,
financial or pecuniary interest in the company. Ms Shore has
sufficient experience that is relevant to the style of
mineralisation and type of deposit under consideration and to the
activities which she 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” and a Qualified Person as defined in NI43-101. Ms Shore
consents to the inclusion in this report of the matters based on
his information in the form and context in which it appears.
The information in this report that relates to
Mineral Reserves for the Sissingué deposit is based on information
compiled by Mr Craig Fawcett, FAusIMM CP, who is a full-time
employee of Perseus Mining. Mr Fawcett has sufficient experience
which is relevant to the style of mineralisation and type of
deposit under consideration and to the activities which 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” and a Qualified Person
as defined in NI43-101. Mr Fawcett consents to the inclusion in
this report of the matters based on his information in the form and
context in which it appears.
The information in this report that relates to
Mineral Resource and Ore Reserve estimates for the Fimbiasso
deposits was first reported by the Company in a market announcement
“Perseus Mining Updates Mineral Resources and Ore Reserves”
released on 26 August 2020. The information in this report
that relates to Mineral Resource and Ore Reserve estimates for the
Bagoé deposits was first reported by the Company in a market
announcement “Perseus Mining Updates Mineral Resources and Ore
Reserves” released on 24 August 2021. The Company
confirms that all material assumptions underpinning those estimates
and the production targets, or the forecast financial information
derived therefrom, in that market release continue to apply and
have not materially changed. The Company further confirms that
material assumptions underpinning the estimates of Ore Reserves
described in “Technical Report — Sissingué Gold Project, Côte
d’Ivoire” dated 18 December 2017 continue to apply.
Caution Regarding Forward Looking Information:
This report contains forward-looking information
which is based on the assumptions, estimates, analysis and opinions
of management made in light of its experience and its perception of
trends, current conditions and expected developments, as well as
other factors that management of the Company believes to be
relevant and reasonable in the circumstances at the date that such
statements are made, but which may prove to be incorrect.
Assumptions have been made by the Company regarding, among other
things: the price of gold, continuing commercial production at the
Sissingué Gold Mine, the Edikan Gold Mine and the Yaouré Gold Mine
without any major disruption due to the COVID-19 pandemic or
otherwise, the receipt of required governmental approvals, the
accuracy of capital and operating cost estimates, the ability of
the Company to operate in a safe, efficient and effective manner
and the ability of the Company to obtain financing as and when
required and on reasonable terms. Readers are cautioned that the
foregoing list is not exhaustive of all factors and assumptions
which may have been used by the Company. Although management
believes that the assumptions made by the Company and the
expectations represented by such information are reasonable, there
can be no assurance that the forward-looking information will prove
to be accurate. Forward-looking information involves known and
unknown risks, uncertainties, and other factors which may cause the
actual results, performance or achievements of the Company to be
materially different from any anticipated future results,
performance or achievements expressed or implied by such
forward-looking information. Such factors include, among others,
the actual market price of gold, the actual results of current
exploration, the actual results of future exploration, changes in
project parameters as plans continue to be evaluated, as well as
those factors disclosed in the Company's publicly filed documents.
The Company believes that the assumptions and expectations
reflected in the forward-looking information are reasonable.
Assumptions have been made regarding, among other things, the
Company’s ability to carry on its exploration and development
activities, the timely receipt of required approvals, the price of
gold, the ability of the Company to operate in a safe, efficient
and effective manner and the ability of the Company to obtain
financing as and when required and on reasonable terms. Readers
should not place undue reliance on forward-looking information.
Perseus does not undertake to update any forward-looking
information, except in accordance with applicable securities
laws.
ASX/TSX CODE: PRUREGISTERED
OFFICE:Level 2, 437 Roberts RoadSubiaco WA 6008Telephone:
+61 8 6144 1700Email:
IR@perseusmining.comWWW.PERSEUSMINING.COM |
CONTACTS:Jeff
QuartermaineManaging Director &
CEOjeff.quartermaine@perseusmining.comNathan
RyanMedia Relations+61 4 20 582
887nathan.ryan@nwrcommunications.com.auClaire
HallCorporate Communications +61 414 558
202claire.hall@perseusmining.com |
APPENDIX 1:
Sissingué Gold Mine Mineral Resources & Ore Reserves
Mineral Resource Statement
Material information summary as required under ASX Listing Rule
5.8 and JORC 2012 reporting guidelines.
The Mineral Resource Statement for the Sissingué Gold Mine (SGM)
is reported in accordance with the 2012 Australasian Code for
Reporting of Exploration Results, Mineral Resources and Ore
Reserves (the JORC Code). The classification categories of
Measured, Indicated and Inferred under the JORC Code are equivalent
to the Canadian Institute of Mining, Metallurgy and Petroleum
categories of the same names (CIM, 2014).
This Mineral Resource Estimate (MRE) update includes an
additional 24,700 m drilling from 528 Reverse Circulation (RC)
holes, drilled in 2021 and is reported excluding mining activity,
surveyed up to 31 December 2021 and limited within a constraining
pit shell generated at US$1,800 an ounce with updated Sissingué
mining and processing costs.
The SGM MRE is comprised of the remaining in situ mineralisation
at the SGM mine and material on stockpiles as of 31 December 2021.
A total of 46,377 metres of drilling from 13,703 drill holes was
available for this MRE. Mineralisation interpretations were
informed by Reverse Circulation and Diamond Drilling.
This MRE comprises Inferred Mineral Resources which are unable
to have economic considerations applied to them, nor is there
certainty that they will be converted to Measured or Indicated
Resources through further sampling. The in situ Mineral Resources
are potentially exploitable by open pit mining methods.
The information provided in the JORC 2012 Table 1 –
Section 3 Estimation and Reporting of Mineral Resources
applies to this MRE.
The combined global Mineral Resource for the SGM is estimated as
2.6Mt grading 1.3 g/t gold, containing 108,000 ozs of gold.
Additional stockpile inventory, provide a total global Mineral
Resources of 7.3Mt @ 1.3g/t for 135,000ozs as shown below in
Table 1.
Table 1: SGM Measured and Indicated Mineral
Resources – 31 December
2021 1,2,3,4,5
DEPOSIT |
DEPOSIT TYPE |
MEASURED RESOURCES |
INDICATED RESOURCES |
MEASURED + INDICATED RESOURCES |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
Sissingué |
Open Pit |
1.2 |
1.4 |
50 |
1.3 |
1.4 |
56 |
2.4 |
1.4 |
107 |
Stockpiles |
Open Pit |
0.7 |
1.3 |
30 |
- |
- |
- |
0.7 |
1.3 |
30 |
Total |
1.8 |
1.3 |
80 |
1.3 |
1.4 |
56 |
3.1 |
1.4 |
135 |
Table 2: SGM Inferred Mineral Resources –
31 December 2021
2,3,4,5
DEPOSIT |
DEPOSIT TYPE |
INFERRED RESOURCES |
QuantityMt |
Gradeg/t gold |
Gold'000 oz |
Sissingué |
Open Pit |
0.1 |
1.1 |
2 |
Total |
0.1 |
1.1 |
2 |
Notes:
1 Measured and Indicated Mineral Resources are
inclusive of Ore Reserves.2 Rounding of numbers may have resulted
in apparent mathematical inconsistencies.3 Based on February 2022
Mineral Resource model constrained to US$1,800/oz pit shell.4
Depleted to 31 December 2021 mining surface.5 0.6g/t gold cut-off
applied to in situ material.
Geology and geological interpretation
The SGM is located in the West African Craton and covers the
Paleoproterozoic (Birimian) rocks of the southern extension of the
Syama Greenstone Belt and the western margin of the Senoufo
Greenstone Belt. Gold deposits at the SGM are orogenic, greenstone
hosted in nature.
The SGM main pit mineralisation is structurally controlled and
mainly hosted within a granitic stock associated with a network of
quartz-carbonate veins and veinlets with pyrite and arsenopyrite
dissemination. Gold-bearing veins have a dominant NNW to NS trend
and are steeply dipping. Disseminated mineralisation is also
located in the alteration envelops of the mineralised quartz
veins.
Additional mineralisation is seen within interconnecting
mineralised felsic dyke complexes that propagate from the main
granite stock. These mineralised felsic dyke complexes, also
trending NNW, host the mineralisation for the additional pits in
the area, namely Binkadi, Bagoé, Western Arm and Boribana.
Interpretations of domain continuity were undertaken within
Leapfrog3DTM software, with mineralisation intercepts correlating
to individual lithological domains manually selected prior to
creation of a vein and intrusion model (Figure 1).
Interpretation was aided by geological pit mapping which ensured
that modelling appropriately represented site-based observations
and the current understanding of geology and mineralisation
controls.
Mineralisation volume domains were delineated using a
combination of:
- Geological
information comprising: Lithology, structural interpretation,
veining and sulphides;
- Utilising a nominal
lower grade minimum cut-off of 0.3 g/t gold.
The main granite intrusions where modelled using lithological
logging and a lower nominal 0.3 g/t gold cut-off, which provided a
low grade (LG) halo mineralised domain. Statistical analysis of the
Granite data showed a high grade (HG) sample population. Visually,
this was supported by a consistent tenor of mineralisation lying as
an internal, higher-grade core within the Granite. This HG internal
sub-domain was then modelled, utilising a nominal 1.0 g/t lower
cut-off. Cross cutting Felsic dyke complexes where then modelled
using structural and lithological logging, assisted by a lower
grade cut-off of 0.3 g/t gold.
Figure 1 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/115283c7-63d6-42dc-8b57-f0832cf4b60c
Sampling and Sub-Sampling
For all RC holes informing the resource estimate, samples were
collected at 1 metre intervals and split at the drill sites using a
multi-stage riffle splitter or cone splitter to produce sub-samples
weighting 2-3 kilograms.
Diamond core was sawn in half with a diamond blade saw, with the
right half sent for assaying and the left half stored in core trays
for reference. Core was sampled in 1 metre intervals or to
geological contacts.
RC and core samples were securely transported to either:
1) Perseus’s sample preparation facility at SGM
where they were dried, crushed to 2mm and a 1kg riffle split
portion pulverised to 90% passing 75 microns and assayed with Aqua
Regia, or
2) Transported to a local laboratory and
assayed using Fire Assay techniques.
Sample condition (dry, damp, wet) and a qualitative description
of sample quality (high, moderate, low) were logged for RC holes.
Holes were stopped if excessive water was intersected and the
samples were considered at risk of smearing, or if sample recovery
dropped to <90%.
For RC samples drilled for resource definition, the weight of
each entire recovered 1 metre sample was recorded with sample
recoveries averaging ~90%. There is no apparent relationship
between sample recovery and gold grades in RC drill holes.
Recovered lengths of diamond core were measured for each drill
run. Average core recoveries range from 85% in upper saprolite to
100% in fresh rock. There is no apparent relationship between core
recovery and gold grades in diamond drill holes.
Sampling precision was monitored by inclusion of 1:20 duplicate
field splits for RC samples. Additionally, duplicate pulps were
created for 1:20 samples of all types.
Database checks were completed and included:
- Checking for
duplicate drill hole names and duplicate coordinates in the collar
table;
- Checking for missing
drill holes in the collar, survey, assay and geology tables based
on drill hole names;
- Checking for survey
inconsistencies including dips and azimuths <0o, dips >90o,
azimuths >360o, negative depth values;
- Checking for
inconsistencies in the “From” and “To” fields of the assay and
geology tables. These checks included the identification of
negative values, overlapping intervals, duplicate intervals, gaps
and intervals where the “From” value is greater than “To”
value.
The drill hole samples are considered appropriate and
representative.
Drilling techniques
The Mineral Resource at Sissingué are delineated from reverse
circulation (RC) and diamond core drilling. Typical drill spacing
is generally less than 25 metres x 25 metres with most holes
drilled at-60 degrees toward either 090 (east) or 270 (west)
degrees azimuth, perpendicular to the strike of mineralisation.
Grade Control drilling spacing is 8 metres x 6 metres, drilled
either at 55 degrees or vertical, with samples collected every 1.5
metres.
The data type, spacing and distribution are considered
sufficient to establish estimates of Mineral Resources.
Sample analysis methods
All gold assaying was completed by external or onsite commercial
laboratories with samples dried, crushed to 10mm, and then
pulverised to 85% passing 75 µm and assayed using a 25g or 50g
charge for fire assay analysis with AAS finish.
Grade control samples were assayed on site using Aqua Regia and
through several external laboratories using Fire Assay between 25g
and 50g aliquots.
Quality Assurance and Quality Control
Assay accuracy and reliability were monitored by insertion of
blanks at 1:20 samples and reference standards (CRMs) at 1:20
samples.
The performances of blanks and standards were monitored as assay
results were received.
Intervals of significant gold grades were compared to logging of
quartz veining, alteration and mineralisation and chip tray
photographs.
Assays were plotted on cross-sections to check that significant
intercepts conform to the expected locations of mineralisation and
make geometric sense.
Diamond core holes have been drilled at Sissingué to twin RC
holes. Portions of 247 RC drill holes were identified to have
smeared assays and have been excluded from all resource estimates,
statistics, and interpolations. They have been appropriately
flagged in the database.
The Quality Assurance and Quality Control (QAQC) data show
acceptable precision and no significant bias. Overall assaying
quality is considered adequate to support estimates of Mineral
Resource.
Estimation methodology – Open pit mineral resources
The 2022 MRE for the SGM was estimated using a combination of
Local Uniform Conditioning (LUC) with Ordinary Kriging (OK) using
Surpac 2021 and Isatis.
Estimation was constrained within mineralisation envelopes
(wireframes) based on geological logging and grade thresholds. The
three main host lithologies are Granite, Felsic Dykes and
Sediments. Where geological contacts were not clearly controlling
the distribution of mineralisation, a grade cut-off of 0.3 g/t gold
was used to construct Mineral Resource boundaries. Analysis of the
global grade distribution shows that there is a natural change in
grade population at around 0.3 g/t gold.
The LUC methodology was used to estimate the gold grades within
the major Granite and Sediment units due to the skewed nature of
the grade populations. At the completion of the estimations, grade,
density and estimation quality items were exported from Isatis and
imported into a Surpac format block model for validation and
reporting.
- Two metre downhole
composite gold grade data were interpolated into 16 mE x 16 mN x 5
mRL sized panels using Ordinary Kriging (OK).
- Top cuts were used
to remove outlier high grades by reviewing composite data globally
and for each individual domain by using histograms, log-histograms,
log-probability plots and high-grade metal sensitivity analysis,
combined with spatial inspection of the grade distribution and
outlier locations. Appropriate high-grade cuts were applied as
required on an individual domain basis. Top cuts used ranged
between 2 and 30 g/t Au.
- A two-pass
estimation strategy was employed. The minimum number of composites
was set at 8 and the maximum number of composites at 16 for the
first pass. A first pass search ellipse radius was set at 60 metres
for these domains. A second pass search had minimum number of
composites set at 5 and the maximum number at 24. The second pass
search ellipse radius was set at 250 metres to ensure all remaining
blocks had been estimated. The orientation of the search ellipse
was set by the variogram model.
- Change of Support
(CoS) calculations were conducted, conditioned to the panel grade
estimates, for selectivity on 2 mE x 4 mN x 2.5 mRL SMU-sized
blocks to produce a recoverable resource estimate. The
Gaussian-based Uniform Conditioning approach was applied to the OK
check grade estimates. An information effect correction was applied
during the CoS calculations, to account for a future theoretical
grade control drill configuration. The CoS process yields a set of
array variables, stored in the panel block model, detailing the
estimates for tonnage, grade, and metal above a range of grade
cut-offs.
- A process of
localisation was completed, by which the output of the CoS is
mapped into single grade estimate per 2mE x 4mN x 2.5mRL block in
an SMU block model, which comprises the final product of the grade
estimation.
The remaining Felsic Dyke domains were estimated using 2m
downhole composite gold grade data into 16 mE x 16 mN x 5 mRL sized
panels using Ordinary Kriging (OK).
- Top cuts were used
to remove outlier high grades by reviewing composite data globally
and for each individual domain by using histograms, log-histograms,
log-probability plots and high-grade metal sensitivity analysis,
combined with spatial inspection of the grade distribution and
outlier locations. Appropriate high-grade cuts were applied as
required on an individual domain basis. Top cuts used ranged
between 2g/t and 30g/t Au.
- The orientation of
the variogram model and search ellipse was dynamically set
according to the orientation of the lodes, as well the trend of
high-grade mineralisation within the unit.
- A three-pass search
pass strategy was used with a 40 metre radii on the first pass,
with the search ellipse doubling in size on successive passes.
- Minimum number of
samples varied from 2 to 8, with a maximum of 16.
Within the Grade Control (GC) volume, which is limited to the
immediate vicinity of the GC drill holes, an OK estimate of gold
grade was produced using the GC drill data.
- A non-linear method
was not considered necessary to reflect the grade distribution
satisfactorily at the 2 mE x 4 mN x 2.5 mRL SMU block scale due to
the very dense ~10 metres GC drill spacing available within this
volume.
- A dynamic oriented
ellipsoidal search radii of 20m was used.
- A three-pass search
strategy was used with the search ellipse doubling in size on
successive pass.
- Minimum number of
samples varied from 2 to 8, with the maximum set at 14.
- Estimation was into
blocks 16 mE x 16 mN x 5 mRL.
Block model validation was undertaken globally by comparing:
- The mean LUC and OK
block grade estimates to the mean of the informing composite grades
on a domain-by-domain basis
- Visual inspection of
the estimated block grades viewed in conjunction with the sample
data
- Using swath plots to
compare the LUC and OK gold estimates to the sample data
- A comparison of the
LUC and GC Models where the LUC local grade model, based only on
the relatively wide spaced resource drill data, was compared to the
high confidence GC OK estimates within the GC volume.
The GC OK estimates are considered to represent a benchmark by
which to measure the success or otherwise of the LUC estimates.
Criteria for resource classification
The SGM MRE has been classified into Measured, Indicated and
Inferred categories, in accordance with the 2012 Australasian Code
for Reporting of Mineral Resources and Ore Reserves (JORC Code) and
the CIM Definition Standards (CIM, 2014). A range of criteria has
been considered in determining this classification, including
geological and grade continuity, data quality and drillhole spacing
resulting in the MRE being classified as Measured, Indicated and
Inferred.
The portions of the MRE classified as Measured have been flagged
using an interpreted volume defined by high quality estimation
parameters, which includes an average distance to nearest sample of
7 metres and an average distance to all informing samples of 12
metres. The Measured portion of the resource has been drilled on a
nominal 6 metres x 8 metres GC spacing.
The portions of the MRE classified as Indicated have been
flagged using a sectional interpreted volume defined by medium to
high quality of estimation parameters, an average distance to
nearest sample of less than 20 metres and an average distance to
all informing samples of less than 40 metres. For the Sediment and
Granite domains within the main Sissingué pit, due consideration
was also given to the geological and mineralisation continuity
available due to mining and positive historical reconciliation.
The portions of the MRE classified as Inferred represent the
material extending down dip within and peripheral within the
mineralised Domains. In these portions, geological continuity
is present but not consistently confirmed by 20 metres x 20 metres
drilling and incorporates volume extensions past the deepest
drilling by up to 40 metres where the domain has not been closed
off by drilling. The Inferred portions of the MRE are defined
by lower confidence of estimation parameters, an average slope of
regression (true to estimated block) of < 0.4 and an average
distance to composites used of > 35 metres.
Mineralisation within the model which did not satisfy the
criteria for Mineral Resource remained unclassified.
Mineral Resources that are not Mineral Reserves do not have
demonstrated economic viability. MRE’s do not account for
selectivity, mining loss and dilution. This MRE includes Inferred
Mineral Resources which are unable to have economic considerations
applied to them, nor is there certainty that they will be converted
to Measured or Indicated Resources through further sampling.
The Mineral Resource estimate appropriately reflects the
Competent Person’s view of the deposit. Optimisations have been run
at a USD$1,800 gold price to define the base of mineralisation
potentially mineable by open pit mining. The Competent Person
endorses the results and classification.
Cut-off grade
The MRE cut-off grade for reporting of global open pit global
gold resources at Sissingué is 0.6 g/t and has been applied to all
materials respectively, based on estimates from mining, ore
transport and processing costs, expected metallurgical performances
of the various material types and a gold price of US$1,800/oz.
Tonnages were estimated on a dry basis.
REASONABLE PROSPECTS FOR EVENTUAL ECONOMIC EXRTRACTION
The SGM MRE, as reported, has been assessed to meet Reasonable
Prospects for Eventual Economic Extraction (RPEEE) based on the
following considerations.
Mineral resources are reported within optimal pit shells
generated using estimates of mining, ore transport and processing
costs, the expected metallurgical performances of the various
material types and a gold price of US$1,800/oz.
Stockpiles
Mineral Resources contained in stockpiles are based on volume
estimates calculated from ground survey data, loose bulk densities
derived over time by reconciliation of volumes mined (at in situ
densities) to stockpile movements and volumes and estimates of
stockpile grades based on predicted grades of mined material
transferred onto stockpiles and material depleted by
processing.
Closing SGM stockpiles as at 31 December 2021 were estimated as
shown in Table 3.
Table 3: SGM Closing Stockpiles – 31 December
2021 1
Material |
QUANTITYkt |
GRADEG/t gold |
GOLDKoz |
Low grade oxide |
54 |
0.6 |
1 |
Low grade fresh |
359 |
1.3 |
15 |
High grade fresh |
249 |
1.5 |
12 |
Total |
662 |
1.3 |
30 |
Notes:
1. Stockpile tonnage and grade estimates are
considered sufficiently accurate to support their classification as
Measured Mineral Resources.
ORE RESERVE STATEMENT
Material information summary as required under ASX Listing Rule
5.9 and JORC 2012 reporting guidelines.
The updated Ore Reserve estimate for SGM is a depletion of the
previous SGM Ore Reserve and update of Ore Reserve estimation based
on the latest Mineral Resource estimate for the Sissingué deposit.
Further information regarding updates to the Sissingué Ore Reserves
are detailed in JORC Table 1 – Section 4 Estimation and
Reporting of Ore Reserves.
The SGM Ore Reserve is summarised below in Table
4 and is estimated at 2.6 Mt of ore, grading 1.3 g/t gold
and containing 108k ounces of gold. The classification categories
of Proved and Probable under the JORC Code (2012) are equivalent to
the CIM categories of the same name (CIM, 2014).
Table 4: SGM Proved and Probable Ore Reserves as at
31 December 2021 5,7
PROJECT |
DEPOSIT TYPE |
PROVED |
PROBABLE |
PROVED AND PROBABLE |
QUANTITYMt |
GRADEG/t gold |
GOLD‘000 oz |
QUANTITYMt |
GRADEG/t gold |
GOLD‘000 oz |
QUANTITYMt |
GRADEG/t gold |
GOLD‘000 oz |
Sissingué1,2,3,4 |
Open Pit |
1.0 |
1.3 |
40 |
0.9 |
1.3 |
37 |
1.9 |
1.3 |
78 |
Stockpiles6 |
Stockpile |
0.7 |
1.3 |
30 |
- |
- |
- |
0.7 |
1.3 |
30 |
TOTAL |
1.7 |
1.3 |
71 |
0.9 |
1.3 |
37 |
2.6 |
1.3 |
108 |
Notes:
1. Based on depletion to 31 December 2021 mining surfaces.2.
Based on Mineral Resource Estimates which were current at February
2022.3. Based on February 2022 Ore Reserve estimation.4. Variable
gold grade cut-off for each material type, ranging from 0.40 g/t to
1.00 g/t5. Inferred Mineral Resource is considered as waste.6.
Based on EOM December 2021 stockpile balance report.7. Rounding of
numbers to appropriate precisions may have resulted in apparent
inconsistencies.
The changes in the Ore Reserve from last quoted in June 2021 are
associated with ore depletion from mining since 30 June 2021 up to
31 December 2021 along with revised Sissingué Ore Reserves driven
by an updated resource model. The waterfall graph (Figure
2) below summarises the changes in the SGM Ore
Reserves.
Figure 7 is available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/d80a4458-8379-4fab-8724-d6b7c43882d6
Economic assumptions
- Gold metal price
US$1,600/oz is used for Sissingué deposit pit optimisation, with
the cut-offs based on US$1,500/oz gold price.
- Average costs used
in optimising pit designs are as shown in Table 5
below.
- A discount rate of
10% (real) has been assumed to calculate net present values of
forecast cash flows.
Table 5: Assumed LOM average operating costs including
Fimbiasso and Bagoé deposits
MINING (OPEN PIT) |
PROCESSING |
G&A |
SELLING |
ROYALTIES |
US$5.67t/mined |
US$16.11/milled |
US$12.11t/milled |
US$3.75/oz sold |
4.5 |
% |
open pit mining parameters
- The chosen method
for the Ore Reserves is conventional open pit mining utilising
hydraulic excavators and trucks, mining bench heights of 5 metres
with 2.5 metre flitches to minimise ore loss and dilution.
- The economic pit
shell was defined using Whittle pit optimisation software (Whittle)
with inputs such as geotechnical parameters, ore loss and dilution,
metallurgical recovery and mining costs.
- The pit optimisation
was run with revenue generated only by Measured and Indicated
Mineral Resources. No value was allocated to Inferred Mineral
Resources.
- Whittle 4X input
parameters were based on Perseus’s operating site experience and
supporting technical studies.
- The pit slope design
assumptions are based on a geotechnical study by George Orr and
Associates (Australia) Pty Ltd for Sissingué . Overall pit slopes
are 30 to 50 degrees inclusive of berms spaced at between 5, 10 and
20 metres vertically and berm widths of 4 to 7 metres.
- Pit ramps have been
designed for a 40 tonne articulated dump truck fleet and are set at
16 metres (dual lane) to 10 metres (single lane).
- Vertical mining
advance has been capped to 75m/year based on Perseus’s operating
experience.
- Minimum mining width
of 40 metres was generally applied to the pit cutback designs.
- There are no
physical constraints to mining within the lease areas. No
property, infrastructure or environmental issues are known to exist
which may limit the extent of mining within the mining areas.
- Ore from Sissingué
pits will be stockpiled on designated location based on rock type
and grade.
- Ore cut-off grades,
based on the gold price, cost and processing parameters, are as
shown in Table 6.
Table 6: Open Pit Cut-Off Grades
DEPOSIT |
CUT-OFF GRADE BY ORE TYPE (G/T GOLD) |
OXIDE |
TRANSITION |
FRESH GRANITE |
FRESH SEDIMENT/MAFIC |
Sissingué |
0.40 |
0.60 |
0.80 |
1.00 |
Processing parameters
- The process
metallurgical recovery for gold is assigned by material type in
each deposit. Gold recovery rates range from 93% for oxide ore to
89% for fresh ore. Recovery variation is a function of differing
metallurgical properties of different material type of ores from
each deposit. The metallurgical recoveries are as shown in
Table 7.
- No deleterious
material has been identified.
- Average annual
processing throughput rate of ore is nominally 1.2Mtpa of combined
ore from all deposits, with throughput rates variable by material
type. The processing circuit involves single stage crushing,
semi-autogenous grinding, gravity recovery and CIL.
Table 7: Metallurgical Recoveries by Material Type and
Pit
DEPOSIT |
CUT-OFF GRADE BY ORE TYPE (G/T GOLD) |
OXIDE |
TRANSITION |
FRESH GRANITE |
FRESH SEDIMENT/MAFIC |
Sissingué |
93.11 |
95.0 |
90.0 |
88.82 |
Notes:
- Average value based on formula
(6.0649 * ln (Au_grade) + 92.185)%
- Average value based on formula
(7.63 * In (Au_grade) + 78.5)%
Stockpile parameters
Ore mined from Sissingué deposits will be temporarily stockpiled
based on rock type and grade. Ore from Fimbiasso and Bagoé will be
blended with remaining ore from the Sissingué deposit to keep the
processing plant at full capacity.
Criteria for ore reserve classification
Ore Reserves have been classified based on the underlying
Mineral Resource classifications and the level of detail in the
mine planning. The Mineral Resources were classified as Measured,
Indicated and Inferred. The Ore Reserves, based only on the
Measured and Indicated Resources, have been classified as Proved
and Probable Ore Reserves, respectively.
The Ore Reserve is classified as Proved and Probable in
accordance with the JORC Code (2012) and CIM (2014), corresponding
to the Mineral Resource classifications of Measured and Indicated
and considering other factors where relevant. The deposits’
geological models are well constrained. The Ore Reserve
classification is considered appropriate given the nature of the
deposits, the moderate grade variability, drilling density,
structural complexity and mining history.
JORC 2012 Table 1 – Section 1 sampling techniques and data
(Criteria in this section apply to all succeeding sections.)
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 down hole
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. |
- Data used for
estimating Mineral Resources at Sissingué include:
- 142,249 metres of RC
drilling in 1,937 RC holes;
- 78,824 metres of
diamond core drilling in 406 holes;
- 4,334 metres of
pre-collared diamond core holes in 39 pre-collared diamond core
holes;
- 89,805 metres of
Grade Control RC drilling in 4,444 additional holes;
- 114,032 metres of
Grade Control AC drilling in 6,292 holes
- RC drill holes were
sampled in 1 m Intervals with the majority composited to
2 m samples (by weighing) prior to submission for assay.
Selected infill drill holes were submitted as 1 m samples. 1
and 2 m sub-sample weights nominally of 2.5 kg and 5 kg
respectively.
- Half-core from
diamond drill holes was submitted for assay (‘right’ side
systematically taken; 1.5 m in oxide and transition, 1 m
in fresh).
- RC holes completed
in 2021 and grade control holes were sampled in 1.5 m intervals
with 3kg subsamples riffle split for assay.
- Samples from
pre-2021 resource definition RC and core holes were assayed by 50g
fire assay.
- Samples from 2021
resource definition RC holes and from grade control holes were
assayed using aqua regia digest and AAS.
|
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.). |
- RC drilling (5¼”
diameter), usually 80 m or less in depth. Generally, RC holes have
collar azimuth and inclination only measured.
- Diamond drilling, HQ
in weathered rock, NQ in fresh rock. All diamond holes downhole
surveyed at 30 m intervals.
- 43 core holes
oriented by core spear; 217 holes oriented by “AceTool”
device.
|
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. |
- 1 metre RC
samples weighed and composited to 2 metres.
- Length of recovered
diamond core measured and recovery calculated based on run length;
close to 100% recovery for all core in fresh rock.
- There is no evident
relationship between sample recovery and grade for diamond
drilling.
|
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.Whether logging is qualitative or quantitative in nature.
Core (or costean, channel, etc.) photography.The total length and
percentage of the relevant intersections logged. |
- RC drill chip boards
were prepared, and the chips logged geologically, including rock
type, alteration type and intensity (where recognisable), vein
quartz content in estimated percentage, sulphide mineralisation and
estimated content, and weathering domain.
- Diamond drill core
was geologically and structurally logged and photographed, before
being sawn in half, including fault, fold, cleavage and joint
orientation, lithological contacts, vein orientation and bedding.
Logged items are lithology, weathering, colour, grain size, vein
type and vein volume percentage, sulphide mineralisation and their
estimated percentage, alteration, and alteration intensity.
- All RC and diamond
holes were sampled and assayed in entirety.
- Logging is
considered appropriate and reliable.
|
Sub-sampling 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 sub-sampling
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. |
- In pre-2021 RC
holes, samples were collected at the drill site at 1 m
intervals and split using a multi-stage riffle splitter. Each two
consecutive samples were composited (where applicable) in one bag.
Wet samples were sub-sampled using a spear. Note that all wet
samples have been discarded from data that inform the resource
estimate.
- Diamond core sawn in
half using a motorized diamond blade saw; right half sent for
assaying, left half stored in core trays for reference.
- Both core and RC
samples followed a standard path of drying, crushing and grinding.
Samples were pulverised with a ring mill and thoroughly mixed on a
rolling mat (“carpet roll”), and then 200 g of sub-sample was
collected. Internal laboratory checks required at least 90% of the
pulp passing -75 µm.
- Some RC samples at
depth were identified as having downhole contamination and
resultant smearing of grades as a result of wet drilling in clayey
material. As a result of this, all RC holes in the main Sissingué
deposit area were reviewed and any suspected of containing smeared
assays were removed from the dataset prior to estimation.
Approximately 5% of RC samples were removed due to suspected
downhole contamination. Additional diamond core drilling was
undertaken in 2016 to confirm mineralisation volumes and grades in
the core of the deposit.
- Except for the issue
noted above, the sub-sampling is considered appropriate and
representative.
|
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.For geophysical tools, spectrometers, handheld XRF
instruments, etc., the parameters used in determining the analysis
including instrument make and model, reading times, calibrations
factors applied and their derivation, etc.Nature of quality control
procedures adopted (e.g. standards, blanks, duplicates, external
laboratory checks) and whether acceptable levels of accuracy (i.e.
lack of bias) and precision have been established. |
- A small number of
initial holes were assayed by bottle roll cyanide extraction which
did not produce an accurate result due to incorrect
methodology.
- All subsequent
assaying of pre-2021 resource definition RC and core samples was by
standard 40 or 50g fire assay with AAS finish.
- Samples from 2021
resource definition RC holes and from grade control holes were
assayed by 50g aqua regia digest and AAS finish.
- Field duplicates (RC
only) inserted at 1 in 25.
- No field duplicates
for DD as ¼ core considered as inadequate sample, and submission
remaining ½ core considered undesirable.
- Blanks inserted at 1
in 25.
- Certified standards
at 1 in 50 up to 2008; thereafter at 1 in 20.
- Internal laboratory
standards, duplicates and repeats and various other tests have been
carried out throughout the drilling programs.
- QAQC shows no bias,
but only moderate reproducibility, particularly at high grades.
This is due to the occurrence of particulate gold at
Sissingué.
- Overall assaying
quality is considered acceptable except for the potential smearing
in some RC samples that were subsequently removed from the dataset
prior to estimation as described above.
|
Verification of sampling and assaying |
The verification of significant intersections by either independent
or alternative company personnel.The use of twinned
holes.Documentation of primary data, data entry procedures, data
verification, data storage (physical and electronic)
protocols.Discuss any adjustment to assay data. |
- During 2016, Perseus
drilled several diamond core holes to confirm the grade tenor and
check RC drill holes suspected of downhole contamination and
smearing. As a result of this program, approximately 5% of RC
samples were removed from the dataset where the RC grades were not
supported by the diamond core drilling.
- Drill hole
information for pre-2021 RC and diamond core holes was captured at
the drill site on paper.
- All hard copies were
delivered to the database administrator in Tengréla site office and
the information entered into a digital relational database.
- All hard copies are
now stored at Sissingué mine site exploration office.
- Logging and sampling
hardcopy records for 2021 resource definition drilling and grade
control drilling are stored at the Sissingué mine.
- Downhole survey data
and collar survey data were provided by drilling contractors and
surveyors respectively in digital format.
- Data for resource
definition drill holes are stored in a centralised acQuire
database. Database administration is based in Perseus’ office in
Accra/Ghana and under the supervision of a dedicated Database
Manager.
- Data for grade
control drill holes are stored at Sissingué mine in a MS Access
relational database maintained by mine geologists.
- No adjustments were
made to the raw assay data except for the removal of any RC samples
with suspected smearing of grades as previously discussed. Top
cutting is only applied after database compositing and statistical
analysis and prior to resource estimation.
|
Location of data points |
Accuracy and quality of surveys used to locate drill holes (collar
and down-hole surveys), trenches, mine workings and other locations
used in Mineral Resource estimation.Specification of the grid
system used.Quality and adequacy of topographic control. |
- All RC and diamond
holes were surveyed using differential GPS, until September 2009 by
a certified contract surveyor (SEMS Exploration Services Ltd,
Ghana). Drill holes between September 2009 and October 2010 were
surveyed by CBM Surveys Ltd of Ghana. All subsequent drill holes
were surveyed by the company’s surveyor.
- Grid system used is
WGS84 UTM Zone 29N with an arbitrary local elevation datum.
- The topography
covering the extent of the Sissingué Mineral Resource model was
created as a digital terrain model (DTM) using the drill hole
collar data, an additional 639 survey points across the
prospect and, elsewhere, SRTM 90m spaced spot heights adjusted to
local height datum.
|
Data spacing and distribution |
Data spacing for reporting of Exploration Results.Whether the data
spacing and distribution is sufficient to establish the degree of
geological and grade continuity appropriate for the Mineral
Resource and Ore Reserve estimation procedure(s) and
classifications applied.Whether sample compositing has been
applied. |
- Data spacing for
resource estimation varies from
10 m x 10 m to 20 m x 20 m
for most areas of the deposit.
- Where data spacing
is wider (to a maximum of 40 m x 40 m), an
Inferred classification is used.
- Data spacing is
sufficient to establish grade and geological continuity appropriate
to the resource estimation procedures and classifications
applied.
- Samples have been
composited (by computer) to 2 m, honouring
geological/mineralisation domains.
|
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.If the relationship between the
drilling orientation and the orientation of key mineralised
structures is considered to have introduced a sampling bias, this
should be assessed and reported if material. |
- Orientation of
drilled section lines is dominantly at right angles to the strike
of the geology and mineralisation domains.
- Drillholes are
angled to cross the sub-vertical dip of the geological
domains.
- Mineralised veins
and their alteration selvages occur at various orientations within
the overall mineralised zones; the estimation method is considered
to account for this.
|
Sample security |
The measures taken to ensure sample security. |
- Samples from RC
drilling were collected and bagged at drill site during the
drilling operation. Core samples were cut in a central facility in
Tengréla and samples placed into sample bags as they were cut.
- All samples
catalogued and placed in large woven bags and sealed prior to
dispatch to ALS, Intertek or BVML for preparation and
analysis.
- Dispatch from site
to Korhogo (Intertek) was undertaken by Perseus staff and
vehicles.
- Samples dispatched
to ALS and BVML were collected from Tengréla by staff and vehicles
of the respective laboratories.
- Samples from 2021
resource definition drilling and from grade control holes have been
prepared and assayed at Sissingué mine site in a laboratory
operated under contract by SGS Mineral Laboratories.
- All aspects of the
process were supervised by Perseus personnel and limited
opportunity exists for tampering with samples.
|
Audits or reviews |
The results of any audits or reviews of sampling techniques and
data. |
- Steffen Brammer of
Perseus reviewed sampling techniques and quality control data
during regular site visits between 2008 and 2013 and considered
them adequate.
- Reviews were also
carried out by Runge Limited during 2009 and 2010 and by Widenbar
& Associates in October 2012 with acceptable conclusions.
- Gary Brabham of
Perseus Mining has reviewed sampling techniques and quality control
data between 2016 and 2021 with acceptable conclusions.
|
JORC 2012 Table 1 – Section 2 Reporting of Exploration
Results
(Criteria listed in the preceding section also apply to this
section.)
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 obtaining a
licence to operate in the area. |
- The Sissingué
Mineral Resource lies within mining permit PE39 (Permit
d’Exploitation Sissingué).
- Perseus holds an 86%
interest in PE39 through the Company’s wholly owned subsidiary
Perseus Mining Côte d’Ivoire SA. The government of Côte d’Ivoire
holds a 10% free carried interest in the property and the remaining
4% interest is held by local joint venture partner Société Minière
de Côte d’Ivoire (SOMICI).
- The mining permit is
valid until 8 August 2022 and is renewable.
- The Government of
Côte d’Ivoire is entitled to a royalty on production as
follows:
|
Spot price per ounce - London PM Fix |
Royalty Rate |
Less than or equal to US$1000 |
3% |
Higher than US$1000 and less than or equal to US$1300 |
3.5% |
Higher than US$1300 and less than or equal to US$1600 |
4% |
Higher than US$1600 and less than or equal to US$2000 |
5% |
Higher than US$2000 |
6% |
- Franco Nevada are
entitled to a 0.5% royalty on production.
- The Sissingué
Project area has no known environmental liabilities.
|
Exploration done by other parties |
Acknowledgment and appraisal of exploration by other parties. |
- Historical
exploration over the Sissingué permit is limited to regional lag
sampling by Randgold Resources during the 1990’s.
- That work identified
several target areas for gold but did not locate the main Sissingué
gold deposit.
|
Geology |
Deposit type, geological setting and style of mineralisation. |
- The Sissingué
Deposit occurs in a strongly deformed Birimian greenstone belt
intruded by quartz-feldspar felsic dykes and granitoid bodies.
- Gold mineralisation
at Sissingué is associated with the felsic dykes and small
granitoid (tonalite) bodies that cross-cut sedimentary rocks.
- Subsequent
hydrothermal activities and metasomatism of the granitoids has led
to a sericite-carbonate alteration within the intrusive and the
more permeable horizons (sandstones and conglomerates) of the
sedimentary rocks, and a low to moderate grade disseminated gold
mineralisation.
- Late-stage high
grade Au-As-quartz-carbonate veins exploited the altered and
brittle portions of the intrusive and sediments with common
occurrences of visible gold.
|
Drill hole Information |
A summary of all information material to the understanding of the
exploration results including a tabulation of the following
information for all Material drill holes:
- easting and northing
of the drill hole collar
- elevation or RL
(Reduced Level – elevation above sea level in metres) of the drill
hole collar
- 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. |
- Individual
exploration results are not being reported in the report to which
this table relates.
|
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.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. |
- Individual
exploration results are not being reported in the report to which
this table relates.
|
Relationship between mineralization 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 drill hole angle is 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’). |
- Individual
exploration results are not being reported in the report to which
this table relates.
- Orientation of
drilled section lines is dominantly at right angles to the strike
of the geology and mineralisation domains.
- Drillholes are
angled to cross the sub-vertical dip of the geological
domains.
|
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
drill hole collar locations and appropriate sectional views. |
- Individual
exploration results are not being reported in the report to which
this table relates.
|
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. |
- Individual
exploration results are not being reported in the report to which
this table relates.
|
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. |
- Individual
exploration results are not being reported in the report to which
this table relates.
|
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).Diagrams clearly highlighting the areas of possible
extensions, including the main geological interpretations and
future drilling areas, provided this information is not
commercially sensitive. |
- Individual
exploration results are not being reported in the report to which
this table relates.
- Sissingué mine has
been operating since early 2018. Estimates of Mineral Resources and
Mineral Reserves are progressively updated as new information comes
to hand. Exploration over satellite deposits is on-going.
|
JORC 2012 Table 1 – Section 3 Estimation and Reporting of
Mineral Resources
(Criteria listed in section 1, and where relevant in section 2,
also apply to this section.)
CRITERIA |
JORC CODE EXPLANATION |
COMMENTARY |
Database integrity |
Measures taken to ensure that data has not been corrupted by, for
example, transcription or keying errors, between its initial
collection and its use for Mineral Resource estimation
purposes.Data validation procedures used. |
- Data for resource
definition drill holes are stored in a centralised acQuire
database. Database administration is based in Perseus’ office in
Accra/Ghana and under the supervision of a dedicated Database
Manager.
- Perseus carried out
detailed validation of the dataset and retains overall
responsibility for the reliability of data that inform the resource
estimate. All drill hole data were validated during data entry by
Perseus including:
- Checks for duplicate
collars
- Checks for missing
samples
- Checks for down hole
from-to interval consistency
- Checks for
overlapping samples
- Checks for samples
beyond hole depth
- Checks for
inexistent or misspelt log items
- Check for missing
assays
- Check for down-hole
information beyond hole depth.
- Additionally,
Perseus carried out statistical and visual validation prior to
estimation including:
- Drillholes with
overlapping sample intervals.
- Sample intervals
with no assay data.
- Duplicate
records.
- Assay grade
ranges.
- Collar coordinate
ranges.
- Valid hole
orientation data.
- No irreconcilable
issues were found, and the data are considered appropriate for
resource estimation.
|
Site visits |
Comment on any site visits undertaken by the Competent Person and
the outcome of those visits. |
- The competent Person
(Christine Shore) conducts regular site visits. During these
visits, the geological structures of the Sissingué Main Pit and
controlling mineralisation were observed, including exploration
activities and ongoing mining operations.
- No material issues
or risks pertaining to the resource were observed during the site
visits
|
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. |
- The geological
confidence is moderate to high, due to the mapping of exposures
within the Main Pit.
- The controls on gold
mineralisation at the main Sissingué deposit and nearby smaller
deposits are understood with reasonable confidence.
- Drill hole logs were
used to guide 3D interpretation of quartz-feldspar felsic dykes and
granite intrusions that are key controls on mineralisation.
- Drill hole logs were
also used to guide interpretations of surfaces delineating
interfaces between laterite, completely weathered, transitional and
fresh rock weathering horizons.
- The factors
affecting continuity both of grade and geology are most likely to
be associated with structural controls and local complexity, the
knowledge of which is limited with the current spacing of
information. The broad approach to the mineralisation modelling in
the Granite and Sediment units is an attempt to model an unbiased
interpretation.
|
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 gold
Mineralisation was domained by its host lithology for modelling
(granite, felsic dykes and sediments). Within the dyke domains,
mineralised sediments in the alteration halo of the dykes were
included to maintain a minimum width of the wireframes and to
maintain continuity along strike. Where geological contacts were
not clearly controlling the distribution of mineralisation, a grade
cut-off of 0.3 g/t Au was used to construct Mineral Resource
boundaries and to provide overall geometry to mineralised zones. A
minimum of 2 m width was used for the wireframes and samples of
grades below the nominal cut-off of 0.3 g/t Au were included where
the wireframe would otherwise be less than 2 m wide. Analysis of
the global grade distribution shows that there is a natural change
in grade population at around 0.3 g/t Au.
- The domains trend
grid north, extend over 2,500 metres strike and dip steeply to the
west and east with horizontal widths varying between 5 to 30 metres
for the dyke associated domains and up to 180 metres in width for
the granite domains. Domains are interpreted to a maximum vertical
depth of 300 metres.
|
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 Mineral
Resource estimate takes appropriate account of such data.The
assumptions made regarding recovery of by-products.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.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 drill hole
data, and use of reconciliation data if available. |
- Domains 100, 101,
400 and 401 were estimated using Localised Uniform Conditioning
(LUC). A non-linear method was deemed appropriate after reviewing
domain statistics.
- Two metre downhole
composite gold grade data were interpolated into 16 mE x 16 mN x 5
mRL sized panels using Ordinary Kriging (OK).
- Top cuts were used
to remove outlier high grades by reviewing composite data globally
and for each individual domain by using histograms, log-histograms,
log-probability plots and high-grade metal sensitivity analysis,
combined with spatial inspection of the grade distribution and
outlier locations. Appropriate high-grade cuts were applied as
required on an individual domain basis. Top cuts used ranged
between 15 and 30 g/t Au.
- The minimum number
of composites was set at 8 and the maximum number of composites was
set at 16 for the first pass. A first pass search ellipse radius
was set at 60 m for these domains. A second pass had minimum number
of composites set at 5 and the maximum number of composites was set
at 24. The second pass search ellipse radius was set at 250 m to
ensure all remaining blocks had been estimated. The orientation of
the search ellipse was set by the variogram model.
- Change of Support
(CoS) calculations were conducted, conditioned to the panel grade
estimates, for selectivity on 2 mE x 4 mN x 2.5 mRL SMU-sized
blocks in order to produce a recoverable resource estimate. The
Gaussian-based Uniform Conditioning approach was applied to the OK
check grade estimates. An information effect correction was applied
during the CoS calculations, to account for a future theoretical
grade control drill configuration. The CoS process yields a set of
array variables, stored in the panel block model, detailing the
estimates for tonnage, grade and metal above a range of grade
cut-offs.
- A process of
localisation was completed, by which the output of the CoS is
mapped into single grade estimate per 2mE x 4mN x 2.5mRL block in
an SMU block model, which comprises the final product of the grade
estimation.
- Remaining resource
domains were estimated using two metre downhole composite gold
grade data into 16 mE x 16 mN x 5 mRL sized panels using Ordinary
Kriging (OK).
- Top cuts were used
to remove outlier high grades by reviewing composite data globally
and for each individual domain by using histograms, log-histograms,
log-probability plots and high-grade metal sensitivity analysis,
combined with spatial inspection of the grade distribution and
outlier locations. Appropriate high-grade cuts were applied as
required on an individual domain basis. Top cuts used ranged
between 3 and 15 g/t Au.
- The orientation of
the variogram model and search ellipse was dynamically set
according to the orientation of the lodes, as well the trend of
high-grade mineralisation within the unit.
- Three search passes
were used with a 40m radii on the first pass, with the search
ellipse doubling in size on successive passes.
- Minimum number of
samples varied from 2 to 8, with a maximum of 16.
- Within the Grade
Control (GC) volume, which is limited to the immediate vicinity of
the GC drill holes, an OK estimate of gold grade was produced using
the GC drill data.
- A non-linear method
was not considered necessary to reflect the grade distribution
satisfactorily at the 2 mE x 4 mN x 2.5 mRL SMU block scale due to
the very dense ~10 m GC drill spacing available within this
volume.
- Dynamic oriented
ellipsoidal search radii of 20m.
- Three search passes
were used with the search ellipse doubling in size on successive
pass.
- Minimum number of
samples varied from 2 to 8, with the maximum set at 14.
- Estimation was into
blocks 16 mE x 16 mN x 5mRL.
- Surpac Mining
Software 2021 and Isatis were used for estimation.
- No by-product
recoveries were considered.
- Block model
validation was undertaken globally by comparing the mean LUC and OK
block grade estimates to the mean of the informing composite grades
on a domain by domain basis, visual inspection of the estimated
block grades viewed in conjunction with the sample data, using
swath plots comparing the LUC and OK gold estimates to the sample
data and comparing the LUC and GC Models where the LUC local grade
model, based only on the relatively wide spaced RDV data, was
compared to the high confidence GC OK estimates within the GC
volume. The GC OK estimates are considered to represent a benchmark
by which to measure the success or otherwise of the LUC
estimates.
|
Moisture |
Whether the tonnages are estimated on a dry basis or with natural
moisture, and the method of determination of the moisture
content. |
- Tonnages are
reported on a dry basis.
|
Cut-off parameters |
The basis of the adopted cut-off grade(s) or quality parameters
applied. |
- The 0.6g/t cut-off
grade for reporting of resources is based on inputs to optimisation
studies carried out as part of the 2022 update of the Sissingué
life-of-mine plan and a gold price of US$1,800/oz.
|
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. |
- Open pit
optimisations were run using current and forecast cost, mining
methods and processing parameters and a gold price of USD$1,800 to
define the base of potentially economic open-pit material for the
Mineral Resource.
|
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. |
- Metallurgical gold
recoveries have been well established by experience through mining
and processing Sissingué ores since January 2018 and these have
been applied to this MRE.
|
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 green fields
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. |
- Perseus has been
issued with an Environmental Permit and all other permits required
to develop and operate an open pit mine and ore processing facility
at Sissingué.
|
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. |
- A total of 770 bulk
density measurements are available from HQ and NQ drill core using
the water displacement method.
- 380 results are from
oxide material, 132 from transitional material and 258 from fresh
material.
- After discarding
possibly erroneous high and low values, mean densities were
calculated and applied to each of the weathering horizons:
- Laterite 1.85 t/ cu
m
- Completely weathered
(oxide) 1.77 t/cu m
- Transition 2.11 t/cu
m
- Fresh rock 2.73 t/cu
m
- The densities are
supported by 294 bulk density measurements undertaken using the
water displacement method of material exposed during mining at
Sissingué to 18 August 2018.
|
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. |
- All relevant
criteria have been considered in the classification of the Mineral
Resources as Measured, Indicated and Inferred.
- The portions of the
MRE classified as Measured have been flagged using an interpreted
volume defined by high quality of estimation parameters, which
includes an average distance to nearest sample of 7 m and an
average distance to all informing samples of 12 m. The Measured
portion of the resource has been drilled on a nominal 6 m x 8 m GC
spacing.
- The portions of the
MRE classified as Indicated have been flagged using a sectional
interpreted volume defined by medium to high quality of estimation
parameters, an average distance to nearest sample of less than 20 m
and an average distance to all informing samples of less than 40 m.
For the sandstone and granite domains within the main Sissingué pit
due consideration was also given to the geological and
mineralisation continuity.
- The portions of the
MRE classified as Inferred represent the material extending down
dip within and peripheral to the mineralised Domains. In these
portions geological continuity is present but not consistently
confirmed by 20 m x 20 m drilling and incorporates volume
extensions past the deepest drilling by up to 40 m when the domain
is not closed off by drilling. The Inferred portions of the MRE are
defined by low quality of estimation parameters, an average slope
of regression (true to estimated block) of < 0.4 and an average
distance to composites used of > 35 m.
- The Mineral Resource
estimate appropriately reflects the Competent Person’s view of the
deposit. Trial optimisations have been run at a USD1,800 gold price
to define the base of material potentially mineable by open pit
mining.
- The Competent Person
endorses the results and classification.
|
Audits or reviews |
The results of any audits or reviews of Mineral Resource
estimates. |
- The Mineral Resource
estimation procedure and results have been internally
reviewed.
|
Discussion of relative accuracy/ confidence |
Where appropriate a statement of the relative accuracy and
confidence level in the Mineral Resource estimate 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.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. |
- Although the
estimate for gold is without bias, some of the estimated volume
however is based on relatively wide spaced data. The estimate is
therefore of moderate confidence and expected to be of moderate
relative accuracy at the local (SMU) scale when drilling density
exceeds 20 m x 20 m. Infill grade control drilling will
be required to improve the confidence of the local estimate.
- The LUC estimate has
been compared to the OK estimates and in a limited volume to an OK
estimate of close spaced grade control drilling. Differences have
been identified; however, these do not exceed expectations and no
material issues have been identified in these comparisons and the
LUC estimate appropriately represents the source data.
|
JORC 2012 Table 1 – Section 4 Estimation and Reporting of Ore
Reserves
CRITERIA |
JORC CODE EXPLANATION |
COMMENTARY |
Mineral Resource estimate for conversion to Ore Reserves |
Description of the Mineral Resource estimate used as a basis for
the conversion to an Ore Reserve.Clear statement as to whether the
Mineral Resources are reported additional to, or inclusive of, the
Ore Reserves. |
- The open pit Mineral
Resources for Sissingué based on information compiled by Ms
Christine Shore (Fellow AusIMM) of Perseus Mining who is the
Competent Person for the Mineral Resource estimates.
- Mineral Resources
quoted in this report are inclusive of Ore Reserves.
|
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. |
- Mr Craig Fawcett as
the Competent Person for the purpose of a JORC Ore Reserve has
regularly visited the mine.
|
Study status |
The type and level of study undertaken to enable Mineral Resources
to be converted to Ore Reserves.The Code requires that a study to
at least Pre-Feasibility Study level has been undertaken to convert
Mineral Resources to Ore Reserves. Such studies will have been
carried out and will have determined a mine plan that is
technically achievable and economically viable, and that material
Modifying Factors have been considered. |
- The Mineral
Resources have been converted to Ore Reserves by means of a Life of
Mine plan including economic assessment.
- Ore Reserves are
determined from technically achievable pit designs based on Open
Pit Optimisation. The designs were assessed to ensure economic
viability.
|
Cut-off parameters |
The basis of the cut-off grade(s) or quality parameters
applied. |
- The cut-off grade is
based on the economic parameters developed for the Operation. The
cut-off grade varies by material types as follows;
|
PIT |
OXIDEAu g/t |
TRANSITIONAu g/t |
FRESH GRANITEAu g/t |
FRESH SEDIMENTAu g/t |
Sissingué Main |
0.40 |
0.60 |
0.80 |
1.00 |
Boribana |
0.40 |
- |
- |
- |
West Arm |
0.40 |
- |
- |
- |
Binkadi |
0.40 |
- |
- |
- |
Bagoé |
0.80 |
- |
- |
- |
Mining factors or assumptions |
The method and assumptions used as reported in the Pre-Feasibility
or Feasibility Study to convert the Mineral Resource to an Ore
Reserve (i.e. either by application of appropriate factors by
optimisation or by preliminary or detailed design).The choice,
nature and appropriateness of the selected mining method(s) and
other mining parameters including associated design issues such as
pre-strip, access, etc.The assumptions made regarding geotechnical
parameters (e.g. pit slopes, stope sizes, etc.), grade control and
pre-production drilling.The major assumptions made and Mineral
Resource model used for pit and stope optimisation (if
appropriate).The mining dilution factors used.The mining recovery
factors used.Any minimum mining widths used.The manner in which
Inferred Mineral Resources are utilised in mining studies and the
sensitivity of the outcome to their inclusion.The infrastructure
requirements of the selected mining methods. |
- The chosen method of
mining is conventional open pit mining utilising hydraulic
excavators and trucks, mining bench heights of 5 m with 2.5m
flitches to minimise ore loss and waste rock dilution.
- The economic pit
shell was defined using Whittle pit optimisation software
(“Whittle”) with inputs such as geotechnical parameters, ore loss
and dilution, metallurgical recovery and mining costs.
- The pit optimisation
was run with revenue generated only by Measured and Indicated
Mineral Resources. No value was allocated to Inferred Mineral
Resources.
- Whittle input
parameters were generally based on Perseus’s site operating
experience and supporting technical studies.
- Appropriate mining
modifying factors such as ore loss, dilution and design parameters
were used to convert the Mineral Resource to an Ore Reserve.
- The pit slope design
assumptions are based on a geotechnical study by George, Orr and
Associates. Overall pit slopes are 30 to 50 degrees inclusive of
berms spaced at between 5, 10 and 20 metres vertically and berm
widths of 4 to 7 metres.
- Pit ramps have been
designed for a 40 tonne ADT truck fleet and are set at 16 metres
(dual lane) to 10 metres (single lane).
- Vertical mining
advance has been capped based on Perseus’s operating
experience.
- Minimum mining width
of 40 m was generally applied to the pit cutback designs.
- Inferred Resources
have not been included in this mining study.
- There are no
physical constraints to mining within the lease area. No property,
infrastructure or environmental issues are known to exist which may
limit the extent of mining within the mining area
|
Metallurgical factors or assumptions |
The metallurgical process proposed and the appropriateness of that
process to the style of mineralisation.Whether the metallurgical
process is well-tested technology or novel in nature.The nature,
amount and representativeness of metallurgical test work
undertaken, the nature of the metallurgical domaining applied and
the corresponding metallurgical recovery factors applied.Any
assumptions or allowances made for deleterious elements.The
existence of any bulk sample or pilot scale test work and the
degree to which such samples are considered representative of the
orebody as a whole.For minerals that are defined by a
specification, has the ore reserve estimation been based on the
appropriate mineralogy to meet the specifications? |
- Ore from Sissingué
mine will be processed together with ore from Fimbiasso and Bagoé
pits based on blending strategy.
- The Sissingué
processing plant uses crushing, grinding, gravity and cyanide
leaching to extract gold. The plant has a nominal capacity of
1.2Mtpa.
- The processing test
work is representative of the different material types throughout
the Mining area.
- No deleterious
material has been identified.
- The process
metallurgical recovery for gold is fixed by material type in each
deposit:
|
PIT |
OXIDE% |
TRANSITION% |
FRESH GRANITE% |
FRESH SEDIMENT% |
Sissingué Main |
91.9^ |
95.0 |
90.0 |
88.8* |
Boribana |
91.7^ |
- |
- |
- |
West Arm |
94.9^ |
- |
- |
- |
Binkadi |
94.6^ |
- |
- |
- |
Bagoé |
92.1^ |
- |
- |
- |
^ Average value based on formula (6.0649 * ln(Au_grade) + 92.185)%
* Average value based on formula (7.63* In (Au_grade) + 78.5)% |
Environment |
The status of studies of potential environmental impacts of the
mining and processing operation. Details of waste rock
characterisation and the consideration of potential sites, status
of design options considered and, where applicable, the status of
approvals for process residue storage and waste dumps should be
reported. |
- No environmental
issues are known to exist which will prevent open pit mining and
ore processing to continue to operate. Perseus has sufficient space
available for waste dumps to store the expected quantities of mine
waste rock associated with the Sissingué open pit Ore Reserve.
Based on testing to date there is no risk of acid rock drainage as
any potentially acid generating material is encapsulated within
acid neutralising material.
|
Infrastructure |
The existence of appropriate infrastructure: availability of land
for plant development, power, water, transportation (particularly
for bulk commodities), labour, accommodation; or the ease with
which the infrastructure can be provided or accessed. |
- Power supply for
Sissingué processing plant is from on-site power generation already
established.
- Water supply for
processing plant is from river abstraction, groundwater extracted
from dedicated boreholes and decant water for processing
plant.
- Access to site is
via public road via Tengrela to Sissingué.
- A camp is
established at Sissingué site to accommodate non-local
employees.
- Mining workshops and
offices to be established on site
|
Costs |
The derivation of, or assumptions made, regarding projected capital
costs in the study.The methodology used to estimate operating
costs.Allowances made for the content of deleterious elements.The
derivation of assumptions made of metal or commodity price(s), for
the principal minerals and co- products.The source of exchange
rates used in the study.Derivation of transportation charges.The
basis for forecasting or source of treatment and refining charges,
penalties for failure to meet specification, etc.The allowances
made for royalties payable, both Government and private. |
- The mining costs are
based on schedule of rates provided by Perseus mining contractors
and Perseus actual performance. All other operating costs have been
provided by Perseus and its Consultants.
- Non-deleterious
materials have been identified and costed.
- Gold is the only
metal considered in the Ore Reserves.
- All costs are in
US$.
- The transportation
and Refining cost of US$3.75/oz was applied.
- A royalty of 4.5% of
the metal price was applied.
|
Revenue factors |
The derivation of, or assumptions made regarding revenue factors
including head grade, metal or commodity price(s) exchange rates,
transportation and treatment charges, penalties, net smelter
returns, etc.The derivation of assumptions made of metal or
commodity price(s), for the principal metals, minerals and
co-products. |
- A gold price of
US$1,600/oz was used for pit optimisation but the cut-offs for
planning are based on US$1,500/oz gold price.
- Economic modelling
by Perseus is at US$1,500/oz.
- Bullion and Refining
cost of US$3.75/oz was applied.
- A royalty of 4.5% of
the metal price was applied.
|
Market assessment |
The demand, supply and stock situation for the particular
commodity, consumption trends and factors likely to affect supply
and demand into the future.A customer and competitor analysis along
with the identification of likely market windows for the
product.Price and volume forecasts and the basis for these
forecasts.For industrial minerals the customer specification,
testing and acceptance requirements prior to a supply
contract. |
- The demand for gold
is considered at the gold price used.
- It was considered
that gold will be marketable beyond the processing life.
- The processing
forecast and mine life are based on life of mine plans.
- The commodity is not
an industrial metal.
|
Economic |
The inputs to the economic analysis to produce the net present
value (NPV) in the study, the source and confidence of these
economic inputs including estimated inflation, discount rate,
etc.NPV ranges and sensitivity to variations in the significant
assumptions and inputs. |
- A schedule and
economic model have been completed by Perseus on a pre-tax basis
using the Ore Reserves published in this Statement. The inputs used
are as per those stated in the relevant sections of this Statement.
The assessment used a discount rate of 10% which is considered
appropriate.
- The Base Case
results from the financial model confirm that the Project is
economically viable.
- Note that as the
gold price changes so too will the economic limits of the pits and
their Reserves. Consequently, the size of the Project will
therefore adjust to suit the revised economics.
|
Social |
The status of agreements with key stakeholders and matters leading
to social licence to operate. |
- Perseus has
established relevant agreements with local stakeholders.
- Perseus has and will
continue to use skilled expatriate workers and locally sourced
skilled workers.
|
Other |
To the extent relevant, the impact of the following on the project
and/or on the estimation and classification of the Ore Reserves:Any
identified material naturally occurring risks.The status of
material legal agreements and marketing arrangements.The status of
governmental agreements and approvals critical to the viability of
the project, such as mineral tenement status, and government and
statutory approvals. There must be reasonable grounds to expect
that all necessary Government approvals will be received within the
timeframes anticipated in the Pre-Feasibility or Feasibility study.
Highlight and discuss the materiality of any unresolved matter that
is dependent on a third party on which extraction of the reserve is
contingent. |
- The estimate of Ore
Reserves for the Sissingué Open Pits are not materially affected by
any other known environmental, permitting, legal, title, taxation,
socio-economic, marketing, political or other relevant factors
other than that described in the preceding text. It is believed
that the classification of Ore Reserves as set out in the following
sections is reasonable.
|
Classification |
The basis for the classification of the Ore Reserves into varying
confidence categories.Whether the result appropriately reflects the
Competent Person’s view of the deposit.The proportion of Probable
Ore Reserves that have been derived from Measured Mineral Resources
(if any). |
- Ore Reserves have
been classified based on the underlying Mineral Resources
classifications and the level of detail in the mine planning. The
Mineral Resources were classified as Measured, Indicated and
Inferred. The Ore Reserves, based only on the Measured and
Indicated Resources, have been classified as Proven and Probable
Ore Reserves, respectively.
- The Ore Reserve is
classified as Proved and Probable in accordance with the JORC Code,
corresponding to the Mineral Resource classifications of Measured
and Indicated and taking into account other factors where relevant.
The deposit’s geological model is well constrained. The Ore Reserve
classification is considered appropriate given the nature of the
deposit, the moderate grade variability, drilling density,
structural complexity and mining history. Therefore, it was deemed
appropriate to use Measured Mineral Resources as a basis for Proven
Reserves and Indicated Mineral Resources as a basis for Probable
Reserves.
- No Inferred Mineral
Resources were included in the Ore Reserve estimate.
|
Audits or reviews |
The results of any audits or reviews of Ore Reserve estimates. |
- Perseus has
completed an internal review of the Ore Reserve estimate.
- The JORC Code
provides guidelines which set out minimum standards,
recommendations and guidelines for the Public Reporting of
exploration results, Mineral Resources and Ore Reserves. Within the
JORC Code is a “Checklist of Assessment and Reporting Criteria”
(Table 1 – JORC Code). This checklist has been used as a systematic
method to undertake a review of the underlying Study used to report
in accordance with the JORC Code.
- A LOM Plan was
prepared based on the ROM mineable ore contained with the pit
designs. The LOM Plan prepared by Perseus is reasonable and
practical. This confirmed that it was suitable for estimation of
Ore Reserves. An economic model was prepared that confirmed the
Operation to be economically viable.
|
Discussion of relative accuracy/ confidence |
Where appropriate a statement of the relative accuracy and
confidence level in the Ore Reserve estimate 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 reserve within stated
confidence limits, or, if such an approach is not deemed
appropriate, a qualitative discussion of the factors which could
affect the relative accuracy and confidence of the estimate.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.Accuracy
and confidence discussions should extend to specific discussions of
any applied Modifying Factors that may have a material impact on
Ore Reserve viability, or for which there are remaining areas of
uncertainty at the current study stage.It is recognised that this
may not be possible or appropriate in all circumstances. These
statements of relative accuracy and confidence of the estimate
should be compared with production data, where available. |
- The accuracy and
confidence of the inputs are, as a minimum, of a pre- feasibility
level (for the global open pit Ore Reserves).
- The key factors that
are likely to affect the accuracy and confidence in the Ore
Reserves are:
- Accuracy of the
underlying Resource Block Models;
- Changes in gold
prices and sales agreements;
- Changes in
metallurgical recovery; and
- Mining ore loss and
dilution
- The Ore Reserve has
utilised all parameters provided by site as made available.
- The accuracy of the
underlying Mineral Resources is defined by the Resource Category
that the Mineral Resources are assigned to. Only the highest
categories of Resource classification, Measured and Indicated, have
been used as a basis for estimating Ore Reserves.
|
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