Dakota Gold Corp. (NYSE American: DC) is pleased to provide results from the Pre-Feasibility Study metallurgical test program for its Richmond Hill Oxide Heap Leach Gold Project in the Homestake District of South Dakota. Results were generated from a PFS dataset using 24 master-composite column tests that cover the principal lithologic, grade, and oxidation domains at crush sizes of 0.5-inch (12.7 millimeters) and 1-inch (25.4 millimeters) with column leach times varying from 21 to 47 days. These results confirm that Richmond Hill is amenable to heap leaching, with positive gold recoveries of up to 92.0% validating historical test work, and supporting the PFS that remains on track for completion in the fourth quarter of 2026.

Highlights from this Update Include:

• Oxide material recoveries: Twelve oxide column tests ranged in recoveries from 92.0% to 57.3%, with an unweighted arithmetic average of 74.2%. Breccia oxide material returned gold extraction of 92.0% to 90.7%. Oxide leach cycle times are consistently in the 30-to 40-day nominal range. At 0.5-inch crush size for oxide material, ultimate gold recoveries from heap leaching are expected to range from 90.3% to 70.0%, with an 80.4% unweighted paired domain mean.

Table 1. Modeled ultimate recoveries segregated by crush size¹.

• Positive material characteristics: Testing to date has shown no discernible issues with compact permeability, clay material, preg-robbing concerns, or any other characteristics that would impede expected operational or metallurgical performance.
• Additional drilling is underway: Dakota Gold has commenced a definition drill program in the central Project area of Richmond Hill targeting conversion of high recovery breccia-hosted oxide inferred resources to mineral reserves for the Feasibility Study (“FS”). The program is expected to complete approximately 11,000 meters (36,000 feet) of definition drilling during 2026-2027 and the results will support future mine sequencing and optimization opportunities. (See Figure 2)

Jack Henris, CEO, President and Director of Dakota Gold, said, “We are pleased to have completed our comprehensive metallurgical test program for our PFS, a key step in our process to systematically de-risk the Project through disciplined and detailed technical studies for the responsible development of Richmond Hill. The PFS metallurgical test program results support the conversion of Richmond Hill’s geological variability into a practical recovery model for mine planning and process design. Separating oxide from transition material performance gives the Company a clearer basis for recovery assignment, mine sequencing, ore routing, and process optimization. The strong breccia-hosted material recovery response and the defined crush-size trade-offs are important inputs to selecting a technically-sound, capital-efficient, heap leach flowsheet.”

PFS Metallurgical Test Program

The PFS metallurgical test program builds on historical test work and is designed to support PFS level definition of metallurgical variability. More than 100 holes drilled in 2025 were designed in whole or in part to collect metallurgical samples representative of the rock types, lithologies, and geological formations in the proposed mine plan (Figure 1). Representative material was selected to evaluate 24 to 28 potential geometallurgical domains. Forte Dynamics, Inc. (now part of SLR International Corporation) conducted the PFS metallurgical test program, which includes ore characterization, bottle-roll and column-leach testing, comminution and crushing studies, process optimization, deleterious-element characterization and environmental testing.

Based on these results, the definitions used to classify oxide and transition material, the Company does not expect a significant amount of transition material to be part of the mine plan. Additional work will be undertaken on transition material that may be encountered during the mining of oxides. Recovery information for transition material can be reviewed in the Appendix.

Figure 1. Richmond Hill 2025 metallurgical drill program and potential geometallurgical test zones. Red drill hole symbols identify 2025 metallurgical holes; the outlined areas show potential test domains over the S-K 1300 Initial Assessment resource footprint.

Master-Composite Column Results

A summary of the 12 completed oxide material master-composite column tests conducted for the PFS is shown in Table 2. The results for the 12 completed transition material master-composite column tests can be viewed in the Appendix. These results are laboratory extractions. Commercial recovery assumptions will require scale-up, solution-management modeling, and operating allowances which will be finalized in the FS metallurgical test work.

Table 2. Gold oxide material recovery ranges from the supplied master-composite column dataset. Arithmetic averages are descriptive only and are not weighted by grade, contained metal, or planned PFS tonnage.

Summary Table of Master-Composite Bottle-Roll and Column Results

Table 3. Oxide material bottle-roll (74 micron) and column test (“CLT”) extractions from the master-composite column dataset.

Table 4. Approximate tonnage distribution in the deposit.

Current Analysis of Crush Size

The crush-size trade-off studies remain active, with the 0.5-inch modeled mean ultimate gold recovery of 80.4% for oxide material, approximately 4.5 percentage points higher than the corresponding 1-inch case. The benefit of the higher recovery will be evaluated against crushing, conveying, and operating costs. The mean modeled recovery at 1 inch is 75.9% for oxide material.

Interpretation and PFS Application

The oxide material provides the stronger overall heap leach gold response, with a 74.2% unweighted average column extraction. The higher modeled ultimate recovery mean is 80.4% at 0.5 inch, followed by 75.9% at 1 inch. Breccia oxide is the strongest performing material tested, followed by Tertiary intrusive and Precambrian oxide; Deadwood oxide is more variable and will require domain-specific recovery assignment, optimization, and sequencing controls. Oxide material is defined as having a CN/FA ratio ≥0.82 and total sulfur content ≤0.5%.

The ultimate recovery schedule will integrate the available column behavior, master- and sub composite bottle-roll results and domain-specific technical judgment. The PFS will reconcile these assignments against resource model tonnage, mine sequence, permeability, cyanide and lime consumption, solution chemistry and capital and operating cost trade-offs before establishing the production-weighted recovery assumptions used in the PFS economic model.

Next Steps for Advancing the FS

• Complete remaining variability, optimization, load permeability, and environmental test work, including confirmation of recovery behavior in lower performing domains.
• Finalize the geometallurgical domain model and reconcile sample coverage against the updated PFS resource and mine plan.
• Complete crush-size and throughput trade-off studies and finalize the PFS to FS process design criteria.
• Develop production-weighted gold and silver recovery assumptions, together with appropriate commercial scale-up and operating allowances, for the PFS financial model.
• Complete additional detailed bottle-roll, column test work, and variability testing to inform the FS.

Follow-up Richmond Hill Metallurgical and Definition Drill Program

Following review of the metallurgical work, Dakota Gold plans to complete approximately 3,800 meters (~12,500 feet) of metallurgical drilling throughout the Project area, and 11,000 meters (~36,000 feet) of definition drilling in the central Project area of Richmond Hill (Figure 2). Mineralization in the central Project area is hosted primarily within breccia, Precambrian, and Tertiary intrusive rock units which have better oxide gold recoveries. The drill program commenced in the third quarter of 2026 and will continue into 2027. Both programs will be informing the FS expected to be published mid-2027.

The metallurgical holes will be drilled to provide material for new column test work. The definition program will have two principal objectives. First, it will target conversion of a significant amount of modeled inferred oxide breccia-hosted mineralized material to reserve category for initial mine sequencing as this type of material had a high recovery of up to 92.0% in the metallurgical test program. Second, the program will add geochemical information including cyanide-soluble gold and multi-element data to supplement the Company’s drilling and historical gold assay drilling database in the area. These supplemented datasets, together with the ongoing metallurgical test results, will inform the recovery and resource model and subsequent mine planning work as the Company transitions to the FS.

Assay results from this program will be incorporated into the updated Richmond Hill resource model in advance of the FS. The expected result is a better defined, metallurgically informed central Project area, with additional resource category conversions where supported by drilling, assays, and geochemical characterization.

Figure 2. Plan map showing location of Richmond Hill planned metallurgical and definition drill program.

About Dakota Gold Corp.

Dakota Gold is a responsible exploration and development company advancing the Richmond Hill Gold Project toward production as soon as 2029, while continuing to define and expand the high-grade underground gold resource potential at the Maitland Gold Project. Both projects are located on private land within the historic Homestake District of South Dakota, one of the most prolific gold mining regions in the United States.