Denison Mines Corp. (‘Denison’) engages in uranium exploration, development and mining.
Denison’s uranium property interests are held directly by the company and/or indirectly through DMI, Denison Waterbury Corp., and Denison AB Holdings Corp.
Focused on the Athabasca Basin Region of Saskatchewan,
Denison’s Flagship Assets:
An effective 95% interest in, and operator of, the Wheeler River Uranium project (‘Wheeler’ or ‘Wheeler River’), which is host to the high-grade Phoenix and Gryphon urani...
Denison Mines Corp. (‘Denison’) engages in uranium exploration, development and mining.
Denison’s uranium property interests are held directly by the company and/or indirectly through DMI, Denison Waterbury Corp., and Denison AB Holdings Corp.
Focused on the Athabasca Basin Region of Saskatchewan,
Denison’s Flagship Assets:
An effective 95% interest in, and operator of, the Wheeler River Uranium project (‘Wheeler’ or ‘Wheeler River’), which is host to the high-grade Phoenix and Gryphon uranium deposits – together representing the largest undeveloped uranium project in the infrastructure-rich eastern Athabasca Basin.
Denison’s Extensive Portfolio of Other Uranium Properties:
A 70.55% interest in, and operator of, the Waterbury Lake project, which includes the Heldeth Túé and Huskie deposits.
A 22.50% interest in the McClean Lake uranium processing facility and uranium deposits, through its interest in the McClean Lake Joint Venture (‘MLJV’), operated by Orano Canada Inc. (‘Orano Canada’).
A 25.17% interest in the Midwest uranium project (‘Midwest’), which is host to the Midwest Main and Midwest A deposits, through its interest in the Midwest Joint Venture (‘MWJV’), operated by Orano Canada.
Through the company’s 50% ownership of JCU, interests in various uranium project joint ventures in Canada, including the Millennium project (JCU 30.099%), the Kiggavik project (JCU 33.8118%), and Christie Lake (JCU 34.4508%).
An extensive portfolio of exploration properties located in the Athabasca Basin.
Mineral Properties
Denison’s mineral property interests are primarily located in the Athabasca Basin region of northern Saskatchewan, the majority of which are located in the eastern portion of the Athabasca Basin, which is host to considerable existing infrastructure, including uranium mines and mills, as well as provincial powerlines and highways. As of December 31, 2024, Denison had direct interests in 35 mineral properties in the Athabasca Basin, consisting of 227 claims covering approximately 385,000 hectares. Denison holds additional indirect interests in various uranium project joint ventures in Canada through its 50% ownership interest in JCU (Canada) Exploration Company, Ltd. (‘JCU’). Denison also holds an earn-in option to acquire an interest in the KLP from Grounded Lithium.
Athabasca Basin
The Athabasca Basin covers an area of approximately 100,000 square kilometres in northern Saskatchewan and northeastern Alberta. The Athabasca Basin is one of the principal uranium-producing districts in the world and is host to the world’s highest-grade and some of the world’s largest uranium mines and deposits, including the McArthur River mine and Cigar Lake mine, located in the eastern Athabasca Basin.
Wheeler River
Wheeler River, Denison’s material project, is the largest undeveloped uranium project in the infrastructure-rich eastern portion of the Athabasca Basin region, in northern Saskatchewan. The project is host to the high-grade Phoenix and Gryphon uranium deposits, discovered by Denison in 2008 and 2014, respectively. The Wheeler River Joint Venture participants are Denison (90%) and JCU (10%). Denison is the operator/manager of the project. Wheeler River consists of a total of 19 contiguous mineral claims covering 11,720 ha and hosts the Phoenix Deposit and Gryphon Deposit. The Wheeler River property is located within the boundaries of Treaty 10 (entered into between the Government of Canada and the First Nations People of Saskatchewan and Alberta).
Phoenix
Phoenix was discovered in 2008 and can be classified as an unconformity-associated deposit of the unconformity-hosted variety. The deposit straddles the sub-Athabasca unconformity approximately 400 m below surface and comprises three zones (A, B, C, and D) which cover a strike length of about 1.1 km. The Phoenix deposit’s zones A and B comprise an exceptionally high-grade core, averaging 46.0% and 22.3% U3O8, respectively. A lower-grade shell surrounds the high-grade core. The basement mineralization at Zone A occurs within local dilation zones near both ends of the deposit associated with the interpreted cross faults.
The mineralization within the Phoenix deposit is dominated by massive to semi-massive uraninite associated with an alteration assemblage comprising hematite, dravitic tourmaline, illite, and chlorite. Secondary uranium minerals, including uranophane and sulphides, are trace in quantity. Average nickel, cobalt, and arsenic concentrations are at the low end of the range found in other uranium deposits in the Athabasca Basin.
Gryphon
Gryphon was discovered in 2014 and can be classified as an unconformity-related deposit of the basement-hosted variety. The deposit occurs within southeasterly dipping crystalline basement rocks of the Wollaston Supergroup below the regional sub-Athabasca Basin unconformity. The deposit is located from 520 to 850 m below surface, has an overall strike length of 610 m and dip length of 390 m, and varies in thickness between 2 and 70 m, depending on the number of mineralized lenses present.
Mineralization within the Gryphon deposit lenses is dominated by massive, semi-massive, or fracture-hosted uraninite associated with an alteration assemblage comprising hematite, dravitic tourmaline, illite, chlorite, and kaolinite. Secondary uranium minerals, including uranophane and carnotite, and sulphides are trace in quantity. Gangue mineralogy is dominated by alteration clays (illite, kaolinite, chlorite), dravite, and hematite with minor relict quartz, biotite, graphite, zircon, and ilmenite. Only trace concentrations of sulphides comprise galena, chalcopyrite, and pyrite. Notable concentrations of molybdenum and lithium have also been identified within and around the mineralization, represented visually as lepidolite and molybdenite.
Mineral Deposit Type
The Phoenix and Gryphon Deposits are classified as Athabasca Basin unconformity-associated (also unconformity-related and -type) uranium deposits. Phoenix straddles the unconformity contact between the Athabasca sandstone and the underlying basement, signifying the unconformity as a major fluid pathway for uranium mineralization. Gryphon is primarily hosted in the basement rocks, with minor portions of the deposit situated at the unconformity.
Unconformity-associated uranium deposits are pods, veins, and semi-massive replacements consisting of mainly uraninite, close to basal unconformities, in particular those between Proterozoic conglomeratic sandstone basins and metamorphosed basement rocks. The uranium deposits in the Athabasca Basin occur below, across, and immediately above the unconformity, which can lie within a few metres of surface at the rim of the Basin to over 1,000 m deep near its centre. The deposits are formed by extensive hydrothermal systems occurring at the unconformity’s structural boundary between the older and younger rock units.
Two end-members of the deposit model have been defined: a sandstone-hosted egress-type model (i.e., Midwest A deposit), which involved the mixing of oxidized sandstone brine with relatively reduced fluids issuing from the basement into the sandstone, and a basement-hosted, ingress-type deposit (i.e., Rabbit Lake deposit), formed by fluid-rock reactions between oxidizing sandstone brine entering basement fault zones and the local wall rock.
Exploration
Since 2004, Denison has completed ground geophysical surveys over the Wheeler River property, including the DC resistivity surveys that identified the drilling target that led to the discovery of the Phoenix deposit in 2008. In 2004, a GEOTEM airborne EM and magnetic survey collected data covering the entire Wheeler River Project, while a FALCON airborne gravity gradiometer survey in 2005 targeted the unconformity uranium mineralization. A helicopter-borne versatile time-domain electromagnetic (‘VTEM’) magnetic-radiometric survey was conducted over the Wheeler River Project in 2013 in an attempt to remove noise in the interpretation of a previous survey. Resistivity and EM surveys continue to be the preferred ground geophysical surveying methods on the Wheeler River project, with the most recent survey consisting of a Stepwise Moving Loop EM (SWML EM) survey initiated in late 2024.
Other Exploration & Evaluation Projects
Waterbury Lake 2024 Activities
The Waterbury Lake property interests are owned by the WLULP, which is a partnership between Denison (70.53%) and KWULP (29.45%), as limited partners, and WLUC (0.02%), as general partner. Denison holds a 60% interest in WLUC (KWULP, 40%) and, in aggregate, holds a 70.55% interest in the WLULP through its limited partner and general partner ownership interests (KWULP, 29.45%). Denison is the operator of the project.
The Waterbury Lake property is located within the eastern part of the Athabasca Basin in Northern Saskatchewan, which is within Treaty 10, in Nuhenéné / Athabasca Denesuliné territory, and within the homeland of the Métis.
The Waterbury Lake project, as of December 31, 2024, consists of thirteen (13) mineral dispositions covering 40,256 ha and contains two deposits: the THT deposit and Huskie deposit. The deposits are located within the property near its eastern edge.
McClean Lake 2024 Exploration & Evaluation Activities
The McClean Lake project is owned by Denison (22.5%) and Orano Canada (77.5%). Orano Canada is the operator/manager of the projects.
The McClean Lake property is located within the eastern part of the Athabasca Basin in northern Saskatchewan, approximately 26 kilometres west of the Rabbit Lake mine and approximately 750 kilometres north of Saskatoon. Access to the McClean Lake site is by both road and air. Goods are transported to the site by truck over an all-weather road connecting with the provincial highway system. Air transportation is provided through the Points North airstrip, located approximately 25 kilometres from the project site. The mineral property consists of four mineral leases covering an area of 1,147 hectares and 13 mineral claims covering an area of 3,111 hectares.
Midwest 2024 Activities
The MWJV is operated by Orano Canada and is host to the high-grade Midwest Main and Midwest A uranium deposits, which lie along strike and within six kilometres of the THT and Huskie deposits at Waterbury Lake. The Midwest and Waterbury deposits are all located in close proximity to existing uranium mining and milling infrastructure, including provincial highways, powerlines, and Denison’s 22.50% owned McClean Lake mill.
McClean Lake Mill & Cigar Lake Toll Milling
The MLJV owns a state-of-the-art uranium processing facility located on the eastern edge of the Athabasca Basin in northern Saskatchewan, approximately 750 kilometres north of Saskatoon. Orano Canada is the operator/manager of the facility.
Mill Licence
The McClean Lake site is operated under various permits, licences, leases, and claims granted and renewed from time to time, all of which are currently in good standing.
Cigar Lake Toll Milling – Ecora Transaction
Pursuant to the Ecora Transaction in February 2017, certain of Denison’s interests in the Cigar Lake toll milling proceeds have been sold to Ecora and its subsidiary Centaurus Royalties Ltd. (‘Centaurus’).
SABRE Mining Program
The Surface Access Borehole Resource Extraction (SABRE) program is focused on developing a viable alternate mining method combining surface drilling and borehole mining technology.
In January 2024, Denison and Orano Canada announced that the MLJV approved a restart of uranium mining operations using the joint venture’s patented SABRE mining method. Mining is planned to commence at the McClean North deposit Pod 1 East in 2025. Activities during 2024 focused on preparations necessary to ready the existing SABRE mining site and equipment for continuous commercial operations, as well as the installation of access holes for the first mining cavities planned for excavation.
Government Regulation
Denison, under the direction of the Canadian Nuclear Safety Commission (‘CNSC’), updated the Environmental Assessment (‘EA’) Project Description to reflect the change, which was submitted and accepted by the regulators in December 2020.
In October 2022, Denison announced a significant regulatory milestone for Wheeler River with the submission of the draft Environmental Impact Statement (‘EIS’) to the Saskatchewan Ministry of Environment (‘SKMOE’) and the CNSC.
The company has worked closely with the primary regulatory agencies involved in the Project, the CNSC and the SKMOE, in order to ensure that the company’s methodology for the EA assessment components is in line with regulatory requirements and expectations.
In October 2024, Denison submitted the final EIS to the SKMOE, in substantially the same form as the EIS that has been submitted to the CNSC.
Environmental matters related to the McClean Lake uranium facility and the Midwest project are regulated by the CNSC and the SKMOE.
Licensing and Permitting
Activities at McClean Lake and Midwest are currently carried out under a single operating licence issued by the CNSC and are subject to all applicable federal statutes and regulations, as well as to all laws of general application in Saskatchewan, except to the extent that such laws conflict with the terms and conditions of the licences or applicable federal laws.
Decommissioning activities at Elliot Lake are currently carried out under two decommissioning licences issued by the CNSC: for the Stanrock tailings area and the Denison mine site and tailings areas. Decommissioning of the facilities pursuant to the terms of the decommissioning licences has been completed. The CNSC has initiated the actions to combine the Stanrock and Denison sites under one Waste Facility Operating Licence. There are no significant differences between the different forms of licences. After a lengthy period of care, maintenance, and monitoring, Denison may apply to the CNSC for permission to cease care of the reclaimed sites.
History
The company was founded in 1954. It was formerly known as International Uranium Corporation and changed its name to Denison Mines Corp. in 2006.