Midnight Sun Extends Dumbwa Copper Deposit to Over 5.3 Kilometres; Remains Open Along Strike With Drilling Ongoing
Results include: 93m @ 0.40% Cu, 80m @ 0.39% Cu, 44m @ 0.53% Cu, and 36m @ 0.58% Cu
Vancouver, British Columbia, May 13, 2026 – Midnight Sun Mining Corp. (TSXV: MMA / OTCQX: MDNGF) (“Midnight Sun” or the “Company”) is pleased to report results from drillholes completed on its wholly owned Dumbwa copper deposit, located in Solwezi, Zambia. Dumbwa is in the southeast portion of the Company’s Solwezi Project, centered in the heart of the prolific Domes Region - flanked to the north by First Quantum’s Kansanshi mine and west by Barrick’s Lumwana mine.
Drilling has now surpassed 200 holes for a total of over 42,000 metres (“m”) and results to date confirm near surface copper sulphide mineralisation, over a continuous strike length of 5.3 kilometres (“km”) (see Figures 2 and 3), with assays received for the first ~4km of drilled strike. The initial discovery and delineation drill program continues with 4 rigs focussed on growing the deposit to the north along strike and to extend previously drilled mineralisation east and west. Quality control issues related to laboratory analysis have been resolved, and the related backlog of assays are now largely caught up (see below).
The Company plans to host a technical webinar with Midnight Sun’s COO, Dr. Kevin Bonel, to discuss the results announced in this news release. Details will be included in a separate news release.
Top 20 Drill Highlights:
| Hole ID | From (m) | To (m) | Interval (m) | Cu (%) |
|---|---|---|---|---|
| DBW-25-099R | 58 | 60 | 2 | 0.54 |
| 152 | 245 | 93 | 0.40 | |
| 29 | 33.78 | 4.78 | 0.31 |
| DBW-25-123 | 59 | 67 | 8 | 0.44 | |
| 127 | 207 | 80 | 0.39 | ||
| DBW-25-036 | 0 | 44 | 44 | 0.53 | |
| and | 119.54 | 137 | 17.46 | 0.37 | |
| DBW-25-111 | 52 | 57 | 5 | 1.75 | |
| 63 | 79 | 16 | 0.35 | ||
| 132 | 221 | 89 | 0.25 | ||
| DBW-25-122 | 11 | 20.6 | 9.6 | 0.18 | |
| 77 | 91 | 14 | 0.19 | ||
| 106 | 142 | 36 | 0.58 | ||
| including | 127 | 142 | 15 | 1.03 | |
| 171 | 238 | 67 | 0.30 | ||
| DBW-25-147 | 0 | 17 | 17 | 0.20 | |
| 41 | 102 | 61 | 0.34 | ||
| including | 41 | 47 | 6 | 1.30 | |
| 82 | 85 | 3 | 1.38 | ||
| 111 | 126 | 15 | 0.27 | ||
| 154 | 168.05 | 14.05 | 0.51 | ||
| 182 | 183 | 1 | 1.34 | ||
| DBW-25-064 | 0.7 | 47 | 46.3 | 0.42 | |
| DBW-25-114 | 26 | 32 | 6 | 0.21 | |
| 43 | 87 | 44 | 0.37 | ||
| 122 | 208.5 | 86.5 | 0.15 | ||
| DBW-25-149 | 23 | 40.84 | 17.84 | 0.85 | |
| Including | 31 | 39 | 8 | 1.71 | |
| 50.58 | 72 | 21.42 | 0.38 | ||
| 171 | 197.65 | 26.65 | 0.38 | ||
| DBW-25-110 | 42 | 77 | 35 | 0.36 | |
| 89 | 102 | 13 | 0.34 | ||
| 145 | 154 | 9 | 0.20 | ||
| DBW-25-065 | 91 | 98 | 7 | 0.16 | |
| 127 | 163 | 36 | 0.33 | ||
| DBW-25-106 | 38 | 43 | 5 | 0.19 | |
| 59 | 67 | 8 | 0.4 | ||
| 173 | 210 | 37 | 0.31 | ||
| DBW-25-031 | 27 | 36 | 9 | 0.34 | |
| 119 | 142 | 23 | 0.49 | ||
| 160 | 181 | 21 | 0.34 | ||
| DBW-25-037 | 0 | 42 | 42 | 0.25 | |
| DBW-25-127 | 42 | 72 | 30 | 0.32 | |
| 96 | 107 | 11 | 0.53 | ||
| 174.95 | 180 | 5.05 | 0.29 |
| DBW-25-117 | 42 | 46 | 4 | 0.51 | |
| 67 | 95 | 28 | 0.30 | ||
| 103 | 109 | 6 | 0.19 | ||
| 143 | 182 | 39 | 0.15 | ||
| DBW-25-120 | 13 | 19 | 6 | 0.54 | |
| 89 | 144.5 | 55.5 | 0.15 | ||
| 164 | 172 | 8 | 0.46 | ||
| DBW-25-108 | 10 | 51 | 41 | 0.20 | |
| 106 | 153 | 47 | 0.14 | ||
| DBW-25-054 | 14 | 20 | 6 | 0.19 | |
| 37 | 54 | 17 | 0.47 | ||
| including | 37 | 38 | 1 | 5.94 | |
| 64.3 | 66 | 1.7 | 0.57 | ||
| 79 | 86 | 7 | 1.01 | ||
| DBW-25-148 | 72.2 | 78 | 5.8 | 0.18 | |
| 86 | 102 | 16 | 0.17 | ||
| 119 | 139.7 | 20.7 | 0.17 | ||
| 169 | 190 | 21 | 0.33 |
- Assay results based on four-acid digest, ICP-OES finish. Intervals listed are based on drilling intervals and therefore are considered relative rather than true widths.
- The full table of assays including locations is available on the Company’s website and can be accessed through this link: Dumbwa Drill Hole Location and Assay Table.
“What began as a geological concept has now been established as a significant discovery, with over 5.3km of strike now tested and supported by more than 40,000m of drilling. Our team is rapidly defining what is emerging as an exceptionally large, near-surface, structurally controlled copper sulphide deposit” stated COO, Kevin Bonel.
“We are developing a clear understanding of Dumbwa and can see the hallmark ‘pinch-and-swell’ geometry typical of major structurally controlled systems and have confirmed unequivocally that Dumbwa is a basement-hosted, strain-related deposit, geologically comparable in every way to Barrick’s Lumwana. We also recognize a predictable grade distribution along strike, with broader higher-grade zones separated by narrower lower-grade domains. Most importantly, we are continuing to establish meaningful scale with each step north expanding the system and mineralisation remaining open, alongside a clear plan to unlock additional mineralisation within zones identified through earlier drilling.”
Figure 1: Dumbwa drilling to date, plotted on 11.2km Phase One copper-in-soil anomaly, target area.
Figure 2: Dumbwa drilling to date, magnified to show current 5.3km drilled strike extent, plotted on Phase One copper-in- soil anomaly, target area.
Dumbwa Today – Geological Model Verified
The Company’s drilling has now surpassed 200 holes for a total of more than 42,000m over 5.3km of strike, and continues to confirm that Dumbwa is an exceptionally large, very near surface, structurally controlled copper sulphide deposit which remains open for growth. Drill testing has focussed on the upper ~220m of the deposit with the intent of defining a resource amenable to rapid, low strip ratio, lowcost future development. It is noted that some areas of similar mineralisation at the nearby Lumwana project can be traced to vertical depths well beyond 200m. At Dumbwa, east-west width of the mineralised corridor ranges from 200m to greater than 500m. Copper grades are variable ranging from thick lower grade intercepts (> 50 m @ <0.3%) to thick higher-grade intercepts (>25m@>0.5%). Grade variability is pronounced along strike (north-south) and is influenced by cross-cutting northwestsoutheast structures that adversely affect the strain regime and subsequent development of mineralised schists. In contrast, grades are relatively consistent eastwest within the higher, medium and lower grade zones, and across the width of the mineralised corridor.
Figure 3: Assay grade shells superimposed on the Dumba soil anomaly showing the correlation between high soil anomalies and medium to high grade mineralised intercepts at Dumbwa. Drilling continues to follow the soil anomaly north.
The First 5.3km Of Strike – In Detail
As seen in the grade distribution map, the first higher grade zone (the “TRS Block”) starts at the south concession boundary and is approximately 1,800m long, varying from 200m wide to more than 500m wide in places, with scope to increase the known mineralised envelope eastwards and at greater depth.
This is followed by a lower grade zone (“CF Block 1”) ~900m along strike and again averaging around 200m wide. Here the strain in the gneisses is observed as lower and consequently there was poor schistose lens development and weaker mineralisation, although the mineralisation remains persistent along strike.
This lower grade zone transitions into the next higher-grade portion of the deposit (the “ES Block”) which, to date, has been extended for 1,600m along strike at an average width of ~500m, expanding it to over twice the width of the southernmost higher-grade zone.
This brings the drill defined medium-to-high grade zones to a total strike length of 3,300m with widths varying from 200m to over 500m.
In both higher-grade zones, mineralisation depth extent has been demonstrated to start at surface and reach between 175m and 220m deep, with occasional deeper holes demonstrating mineralisation continuing to a depth greater than 300m.
Structurally, the southern part of the Dumbwa copper deposit is weakly broken by late NW-SE trending structural corridors (late brittle faulting) although offset distances are minimal. Early observations on drill core from the area north of strike kilometre 5, the area currently being tested by drilling, indicates more intense late brittle faulting and locally larger offsets, however, the relationship between high strain leading to copper mineralised schist development holds true.
Figure 4: Long Section showing 4km mineralised strike and distribution of bornite and chalcopyrite.
Lumwana Analogue Confirmed
Detailed lithological and structural logging is showing the Dumbwa copper deposit to be a stacked series of horizontal to shallow east dipping copper sulphide mineralised biotite and biotite-muscovite schists (“2 mica schists”) within a barren grey and pink basement gneiss sequence. The schists form in an intimate relationship with strain which has resulted in the schists being variably developed over the 5.3 km that have been drilled to date. Simply put, increasing strain leads to greater schist development, which in turn results in higher copper sulphide concentration.
The relationship between high tectonic strain and the evolution of the copperbearing schists is very clear, and the similarity between Lumwana and Dumbwa has been well established.
As with Lumwana, where there is both high strain and mineralised schist, a kyanitic overprint is commonly observed and these correlate with the highest grades and thickest copper intercepts observed in Dumbwa.
Dumbwa and Lumwana share extraordinary geological similarity, formed by the same basement-hosted structural and mineralisation processes:
| Lumwana | Dumbwa |
| Copper sulphide mineralised biotite and muscovite-biotite schists within a grey and pink gneiss package | Copper sulphide mineralised biotite and muscovite-biotite schists within a grey and pink gneiss package |
| Host rocks ancient basement gneisses | Host rocks ancient basement gneisses |
| Copper mineralisation related to high strain and the evolution of schists as a C1 fabric | Copper mineralisation related to high strain and the evolution of schists as a C1 fabric |
| Copper mineralisation dominated by chalcopyrite with bornite and subordinate chalcocite | Copper mineralisation dominated by chalcopyrite with bornite and subordinate chalcocite |
| Lumwana dominated by shallow dipping (south and east) mineralised schists | Dumbwa dominated by shallow (mostly east) dipping mineralised schists |
| Lumwana mineralised schists anastamosed and intercalated with barren grey gneiss as ‘boudins and rafts’ | Dumbwa mineralised schists anastamosed and intercalated with barren grey gneiss as ‘boudins and rafts’ |
| Subsidiary sulphides dominated by pyrite (Chimiwungo) and pyrrhotite (Kamisengo) | Dumba dominated by subsidiary pyrite and rare pyrrhotite |
| Lumwana mineralised schists usually associated with a metasomatic kyanite overprint | Dumbwa mineralised schists usually associated with a metasomatic kyanite overprint |
| Lumwana Chimiwungo mineralisation extends for >4km east-west and >5km north-south, with a shallow dip to the south. It is sheeted, continuing beyond these limits, with grades and thicknesses decreasing away from the core of the | The Dumbwa deposit extends for 200m – 500m east-west and at least 5.3km north-south with planned Phase One exploration drilling to test a further 5.7km north for a total of 11.2km of suspected north-south copper mineralised strike. Phase Two |
deposit. This mineralisation is still will test the northern half of the open to the east and south but 20km copper-in-soil anomaly. pinches out to the west and is down- Stacked mineralised zones go from thrown by a series of late-stage, surface to beyond 300m but average north-dipping, normal faults. The ~175m – 200m.
main body of the Chimiwungo deposit consists of multiple stacked While drilling to date demonstrates mineralised zones, in aggregate Dumbwa having a narrower E-W varying from 40m to over 100m in mineralised corridor (200m-500m thickness (Source: Porterhouse) wide) when compared to Lumwana,
the deposit remains open and has the potential for significantly greater strike length and maximum thickness than Lumwana.
Figure 5: Cross Section through Kamisengo – Lumwana (Source: 2024 Barrick NI-43-101 Technical Report).