1 Refer to the table in Appendix 2 (page 14) of this release for a summary of the key assumptions, operational parameters and economic results and values from the PEA Fortuna Expands Southern Arc Mineralization with Drill Intercept of
NEWS RELEASE
1 Refer to the table in Appendix 2 (page 14) of this release for a summary of the key assumptions, operational parameters and economic results and values from the PEA
Fortuna Expands Southern Arc Mineralization with Drill Intercept of
1.7 g/t Au over 29.6 meters and a further 2.0 g/t Au over 20.0 meters from
DSDD574 at the Diamba Sud Gold Project, Senegal
Vancouver, December 8, 2025: Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) is pleased to report
additional exploration drilling results from the Southern Arc deposit at its Diamba Sud Gold Project in
Senegal. Diamba Sud is a PEA -stage project with robust economics, highlighted by an estimated
after-tax NPV5% of US$563 million and an IRR of 72% at a gold price of US$ 2,750 per ounce. The
project is currently advancing toward a feasibility study and a construction decision targeted for the
second quarter of 2026.
Paul Weedon, Senior Vice President of Exploration, commented “Southern Arc continues to deli ver
strong results with high grade intersections from both infill and extension drilling. Infill highlights include
drillhole DSDD555, which returned 6.8 g/t gold over an estimated true width of 35.5 meters .”
Mr. Weedon continued, “ Importantly, drilling to the southwest of the current optimized pit shell is
expanding mineralization, returning broad and consistent gold intervals. This includes drill hole
DSDD574, which intersected 1.7 g/t gold over an estimated true width of 29.6 meters, and a further
2.0 g/t over an estimated true width of 20.0 meters.” Mr. Weedon concluded, “These results will feed
into an updated resource estimate expected in the first quarter of 2026.”
The PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative
geologically to have the economic considerations applied to them that would enable them to be categorized as
mineral reserves; as such, there is no certainty that the PEA results will be realized. Mineral resources that are
not mineral reserves do not have demonstrated economic viability1
Southern Arc Prospect Drilling Highlights
A further 63 reverse-circulation and diamond drill hole, totalling 9,619 meters, have been completed
at Southern Arc (see Figure 1) since the Company´s previous exploration update (refer to Fortuna
news release dated May 27, 2025 ). Drilling is continuing with five drill rigs, with key objectives
including:
• ongoing infill drilling to support increased resource confidence, and
• continued step-out drilling to the southwest, east , and south, where mineralization remains
open
DSDD555: 6.8 g/t Au
24.0 g/t Au
13.1 g/t Au
18.5 g/t Au
18.7 g/t Au
over an estimated true width of 35.5 meters from 48.6 meters, including
over an estimated true width of 0.8 meters from 65 meters, and
over an estimated true width of 0.8 meters from 68.5 meters, and
over an estimated true width of 0.8 meters from 74 meters, and
over an estimated true width of 5.6 meters from 80 meters
DSDD558: 1.8 g/t Au
8.8 g/t Au
22.1 g/t Au
18.0 g/t Au
11.5 g/t Au
over an estimated true width of 12.8 meters from 25 meters
over an estimated true width of 14.4 meters from 96 meters, including
over an estimated true width of 0.8 meters from 101 meters, and
over an estimated true width of 0.8 meters from 103 meters, and
over an estimated true width of 0.8 meters from 110 meters
-2-
DSDD562: 4.5 g/t Au
8.0 g/t Au
46.3 g/t Au
over an estimated true width of 5.6 meters from 146 meters
over an estimated true width of 11.2 meters from 174 meters, including
over an estimated true width of 1.6 meters from 183 meters
DSDD563: 5.8 g/t Au
23.3 g/t Au
21.8 g/t Au
12.2 g/t Au
14.7 g/t Au
22.1 g/t Au
2.7 g/t Au
7.0 g/t Au
15.3 g/t Au
over an estimated true width of 20.8 meters from 50 meters, including
over an estimated true width of 1.6 meters from 53 meters, and
over an estimated true width of 1.6 meters from 71 meters
over an estimated true width of 5.8 meters from 86 meters, including
over an estimated true width of 0.8 meters from 87 meters, and
over an estimated true width of 2.2 meters from 90 meters
over an estimated true width of 6.4 meters from 106 meters
over an estimated true width of 4.8 meters from 118 meters, including
over an estimated true width of 1.6 meters from 120 meters
DSDD567: 4.6 g/t Au
15.6 g/t Au
13.6 g/t Au
18.3 g/t Au
over an estimated true width of 26.6 meters from 96.8 meters, including
over an estimated true width of 0.8 meters from 103 meters, and
over an estimated true width of 1.6 meters from 105 meters, and
over an estimated true width of 1.6 meters from 114 meters
DSDD574: 1.7 g/t Au
2.0 g/t Au
18.4 g/t Au
over an estimated true width of 29.6 meters from 93 meters
over an estimated true width of 20.0 meters from 135 meters, including
over an estimated true width of 0.8 meters from 158 meters
DSDD577: 4.2 g/t Au
30.0 g/t Au
18.9 g/t Au
over an estimated true width of 21.6 meters from 116.2 meters, including
over an estimated true width of 1.6 meters from 125 meters, and
over an estimated true width of 1.1 meters from 134.3 meters
DSDD578: 4.9 g/t Au
29.5 g/t Au
over an estimated true width of 16.8 meters from 15 meters, including
over an estimated true width of 1.6 meters from 15 meters
DSDD584: 5.5 g/t Au
20.3 g/t Au
14.3 g/t Au
17.8 g/t Au
7.8 g/t Au
over an estimated true width of 17.0 meters from 32.7 meters, including
over an estimated true width of 0.8 meters from 38 meters, and
over an estimated true width of 0.8 meters from 50 meters, and
over an estimated true width of 0.8 meters from 53 meters
over an estimated true width of 1.4 meters from 95.7 meters
DSDD589: 3.5 g/t Au
15.8 g/t Au
over an estimated true width of 26.8 meters from 16 meters, including
over and estimated true width of 0.8 meters from 34 meters
Mineralization at Southern Arc occurs as variabl y developed fine stockwork vein arrays to diffuse
pyrite-silica flooding, showing strong correlation with several tectonic breccia and carbonate units (see
Figures 2 and 3 ). Alteration commonly includes extensive hematite development, consistent with
mineralized systems elsewhere at Diamba Sud.
Overall, the latest drilling reinforces the strong potential for continued resource growth at Diamba Sud.
Southern Arc remains open to the south, east, and at depth, with drilling to date testing to only
approximately 150 meters below surface.
-3-
Figure 1: Location plan showing Diamba Sud drilling and Mineral Resource Deposits
-4-
Figure 2: Diamba Sud Gold Project: Southern Arc Prospect, cross section 550NE
Figure 3: Diamba Sud Gold Project: Southern Arc Prospect, cross section 450NE
-5-
Refer to Appendix 1 for complete drill hole collars, significant intercepts, and assay results for this drill
program.
Quality Assurance & Quality Control (QA - QC)
All drilling data completed by the Company utilized the following procedures and methodologies. All
drilling was carried out under the supervision of the Company’s personnel.
All reverse circulation (RC) drilling used a 5.25 -inch face sampling pneumatic hammer with samples
collected into 60 -liter plastic bags. Samples were kept dry by maintaining enough air pressure to
exclude groundwater inflow. If water ingress exceeded the air pressure, RC drilling was stopped, and
drilling converted to diamond core tails. Once collected, RC samples were riffle split through a three-
tier splitter to yield a 12.5 percent representative sample for submission to the analytical laboratory.
The residual 87.5 percent samples were stored at the drill site until assay results were received and
validated. Coarse reject samples for all mineralized samples corresponding to significant intervals are
retained and stored on-site at the Company-controlled core yard.
All diamond drilling (DD) drill holes started with HQ sized diameter, before reducing to NQ diameter
diamond drill bits on intersecting fresh rock. The core was logged, marked up for sampling using
standard lengths of one meter or to a geological boundary. Samples were then cut into equal halves
using a diamond saw. One half of the core was left in the original core box and stored in a secure
location at the Company core yard at the project site. The other half was sampled, catalogued, and
placed into sealed bags and securely stored at the site until shipment.
All RC and DD samples were transported by Company vehicle or commercial courier to ALS Global’s
preparation laboratories in Kedougou, Senegal or Bamako, Mali, with prepared sample pulps then
transported via commercial courier to ALS Global’s analytical facility in Ouagadougou, Burkina Faso.
Routine gold analysis using a 50 -gram charge and fire assay with an atomic absorption finish was
completed for all samples. Samples returning assays >10 parts per million Au were reanalyzed using
a 50-gram charge and fir e assay with a gravimetric finish. Quality control procedures included the
systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition,
the ALS Global laboratory inserted its own quality control samples.
Qualified Person
Paul Weedon, Senior Vice President, Exploration for Fortuna Mining Corp., is a Qualified Person as
defined by National Instrument 43 -101 being a member of the Australian Institute of Geoscientists
(Membership #6001). Mr. Weedon has reviewed and approved the scientific and technical information
contained in this news release. Mr. Weedon has verified the data disclosed, including the sampling,
analytical and test data underlying the information or opinions contained herein by reviewing
geochemical and geological databases and reviewing diamond drill core. There were no limitations to
the verification process.
-6-
About Fortuna Mining Corp.
Fortuna Mining Corp. is a Canadian precious metals mining company with three operating mines and
a portfolio of exploration projects in Argentina, Côte d’Ivoire, Mexico, and Peru, as well as the Diamba
Sud Gold Project in Senegal. Sustainability is at the core of our operations and stakeholder
relationships. We produce gold and silver while creating long -term shared value through efficient
production, environmental stewardship, and social responsibility. For more information, please visit
our website at www.fortunamining.com
ON BEHALF OF THE BOARD
Jorge A. Ganoza
President, CEO, and Director
Fortuna Mining Corp.
Investor Relations:
Carlos Baca | [email protected] | fortunamining.com | X | LinkedIn | YouTube
-7-
Forward looking Statements
This news release contains forward-looking statements which constitute “forward-looking information”
within the meaning of applicable Canadian securities legislation and “forward -looking statements”
within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of
1995 (collectively, “Forward -looking Statements”). All statements included herein, other than
statements of historical fact, are Forward -looking Statements and are subject to a variety of known
and unknown risks and uncertainties which could cause actual events or results to differ materially
from those reflected in the Forward-looking Statements. The Forward-looking Statements in this news
release may include, without limitation, the projected economics of the Diamba Sud Project, including
the net present value of the Diamba Sud Proj ect and the internal rate of return of the Diamba Sud
Project; the Company’s expectation that a construction decision will be targeted for the second quarter
of 2026; statements regarding continued resource growth at the Diamba Sud Project and the expected
timing of an updated resource estimate; the Company’s proposed exploration plans at Diamba Sud
statements about the Company’s business strategies, plans and outlook; the Company’s plans for its
mines and mineral properties; changes in general economic conditions and financial markets; the
impact of inflationary pressures on the Company’s business and operations; the future results of
exploration activi ties; expectations with respect to metal grade estimates and the impact of any
variations relative to metals grades experienced; assumed and future metal prices; the merit of the
Company’s mines and mineral properties; and the future financial or operatin g performance of the
Company. Often, but not always, these Forward -looking Statements can be identified by the use of
words such as “estimated”, “potential”, “open”, “future”, “assumed”, “projected”, “proposed”, “used”,
“detailed”, “has been”, “gain”, “pl anned”, “reflecting”, “will”, “anticipated”, “estimated” “containing”,
“remaining”, “to be”, or statements that events, “could” or “should” occur or be achieved and similar
expressions, including negative variations.
Forward-looking Statements involve 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 results, performance or achievements expressed o r implied by the Forward -looking
Statements. Such uncertainties and factors include, among others, operational risks associated with
mining and mineral processing; uncertainty relating to Mineral Resource and Mineral Reserve
estimates; uncertainty relating to capital and operating costs, production schedules and economic
returns; risks relating to the Company’s ability to replace its Mineral Reserves; risks related to the
conversion of Mineral Resources to Mineral Reserves; risks associated with mineral exp loration and
project development; uncertainty relating to the repatriation of funds as a result of currency controls;
environmental matters including obtaining or renewing environmental permits and potential liability
claims; uncertainty relating to nature and climate conditions; laws and regulations regarding the
protection of the environment (including greenhouse gas emission reduction and other decarbonization
requirements and the uncertainty surrounding the interpretation of omnibus Bill C -59 and the related
amendments to the Competition Act (Canada); risks associated with political instability and changes
to the regulations governing the Company’s business operations; changes in national and local
government legislation, taxation, controls, regulations and political or economic developments in
countries in which the Company does or may carry on business; risks associated with war, hostilities
or other conflicts, such as the Ukrainian – Russian, and Israeli – Hamas conflicts, and the impacts
they may have on global economic activity; risks relating to the termination of the Company’s mining
concessions in certain circumstances; developing and maintaining relationships with local
communities and stakeholders; risks associated with losing control of public perception as a result of
social media and other web -based applications; potential opposition to the Com pany’s exploration,
development and operational activities; risks related to the Company’s ability to obtain adequate
-8-
financing for planned exploration and development activities; property title matters; risks related to the
ability to retain or extend title to the Company’s mineral properties; risks relating to the integration of
businesses and assets acquired by the Company; impairments; risks associated with climate change
legislation; reliance on key personnel; adequacy of insurance coverage; operational safety and
security risks; legal proceedings and potential legal proceedings; uncertainties relating to general
economic conditions; risks relating to a global pandemic, which could impact the Company’s business,
operations, financial condition and share price; competition; fluctuations in metal prices; risks
associated with entering into commodity forward and option co ntracts for base metals production;
fluctuations in currency exchange rates and interest rates; tax audits and reassessments; risks related
to hedging; uncertainty relating to concentrate treatment charges and transportation costs; sufficiency
of monies al lotted by the Company for land reclamation; risks associated with dependence upon
information technology systems, which are subject to disruption, damage, failure and risks with
implementation and integration; labor relations issues; as well as those factors discussed under “Risk
Factors” in the Company's Annual Information Form for the fiscal year ended December 31, 2024.
Although the Company has attempted to identify important factors that could cause actual actions,
events, or results to differ materially from those described in Forward-looking Statements, there may
be other factors that cause actions, events or results to differ from those anticipated, estimated or
intended.
Forward-looking Statements contained herein are based on the assumptions, beliefs, expectations
and opinions of management, including, but not limited to, the accuracy of the Company’s current
Mineral Resource and Mineral Reserve estimates; that the Company’s activities will be conducted in
accordance with the Company’s public statements and stated goals; that there will be no material
adverse change affecting the Company, its properties or its production estimates (which assume
accuracy of projected ore grade, mining rates, recovery timing, and recovery rate estimates and may
be impacted by unscheduled maintenance, labor and contractor availability and other operating or
technical difficulties); the duration and effect of global and local inflation; the duration and impacts of
geo-political uncertainties on the Company’s production, workforce, business, operations and financial
condition; the expected trends in mineral prices, inflation and currency exchange rates; that all required
approvals and permits wil l be obtained for the Company’s business and operations on acceptable
terms; that there will be no significant disruptions affecting the Company's operations and such other
assumptions as set out herein. Forward-looking Statements are made as of the date h ereof and the
Company disclaims any obligation to update any Forward-looking Statements, whether as a result of
new information, future events, or results or otherwise, except as required by law. There can be no
assurance that these Forward -looking Statements will prove to be accurate, as actual results and
future events could differ materially from those anticipated in such statements. Accordingly, investors
should not place undue reliance on Forward-looking Statements.
Cautionary Note to United States Investors Concerning Estimates of Reserves and Resources
All reserve and resource estimates included in this news release have been prepared in accordance
with National Instrument 43 -101 Standards of Disclosure for Mineral Projects ("NI 43 -101") and the
Canadian Institute of Mining, Metallurgy, and Petroleum Def inition Standards on Mineral Resources
and Mineral Reserves. NI 43-101 is a rule developed by the Canadian Securities Administrators that
establishes standards for public disclosure by a Canadian company of scientific and technical
information concerning m ineral projects. All Mineral Reserve and Mineral Resource estimates
contained in the technical disclosure have been prepared in accordance with NI 43 -101 and the
Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards on Mineral Resourc es
and Reserves. Canadian standards, including NI 43-101, differ significantly from the requirements of
the Securities and Exchange Commission, and mineral reserve and resource information included in
this news release may not be comparable to similar information disclosed by U.S. companies.