Doré Copper Intersects 5.5 m at 3.46% Copper and 0.25 g/t Gold at Corner Bay – Extending Deposit Along Strike by 200 m

Drilling Highlights

Main Vein below dyke

• CB-21-28: 3.7 meters of 5.05% Cu, 0.15 g/t Au and 11.3 g/t Ag, including 1.8 meters of 9.12% Cu, 0.17 g/t Au and 19.2 g/t Ag
• CB-21-29: 3.7 meters of 2.47% Cu, 0.87 g/t Au and 9.3 g/t Ag, including 1.5 meters of 5.25% Cu, 2.05 g/t Au and 12.7 g/t Ag
• CB-21-32: 5.5 meters of 3.46% Cu, 0.25 g/t Au and 8.4 g/t Ag, including 3.6 meters of 4.63% Cu, 0.30 g/t Au, and 11.4 g/t Ag - DEPOSIT EXTENDED BY 200 METERS
  

West Vein

• CB-20-20 (completed in 2021): 4.0 meters of 2.31% Cu, 0.11 g/t Au, and 7.0 g/t Ag
• CB-21-22: 3.2 meters of 2.84% Cu, 0.32 g/t Au, and 6.25 g/t Ag

Ernest Mast, President and CEO of Dor? Copper stated, "We have successfully expanded the size of the high-grade copper-gold Corner Bay deposit with both our 2020 and 2021 drilling programs and are now confident in the potential to reach our key target of 5 million tonnes in resources, which would be an increase of approximately 65% from our 2019 NI 43-101 mineral resource estimate. The furthest southern intercept (hole CB-21-32) is indicating additional growth towards the south along strike and extends the deposit past the previously understood plunging mineralization. We have expanded our drilling program to the south (along strike) to continue delineating the mineralization. We are planning to have an updated mineral resource estimate in early Q3 to support an eventual hub-and-spoke restart of the camp using our existing 2,700 tpd mil, with Corner Bay as the main feed to the mill. In addition, the increased strike length and thicknesses at depth at Corner Bay lend itself to increased mining rates over time."

Corner Bay Drilling Program

Results to date from the 2021 drilling program has successfully continued to expand the copper-gold mineralization at Corner Bay, bringing the total strike of the mineralization to over 900 meters. The intercepts of holes CB-21-28, CB-21-29, and CB-21-32 have extended the Main Vein (below the diorite dyke) along strike to the south by approximately 200 meters from the 2020 drilling program (see Figure 1 and Table 1). The high-grade copper intercept of 5.5 meters of 3.46% Cu (including 3.6 meters of 4.63% Cu) in CB-21-32 (southernmost hole for this part of the deposit) is located 380 meters south along strike from the 2019 mineral resource limit. The intercept in hole CB-21-32 also demonstrated that the "La Chib" fault, which limited the upper part of the deposit, does not limit the mineralization in the deeper part of the deposit and therefore opens up this part of the deposit along strike.

The drilling program also tested the extension of the West Vein (located 400 meters west of the Main Vein) with four shallow holes. Note that two deeper holes testing the deeper part of the deposit did intersect the West Vein on the way down as well. The best intercepts included 4.0 meters of 2.31% Cu, 0.11 g/t Au, and 7.0 g/t Ag (hole CB-20-20) and 3.2 meters of 2.84% Cu, 0.32 g/t Au, and 6.25 g/t Ag (hole CB-21-22). The mineralization is approximately 200 meters from surface and extends for approximately 150 meters vertically and 200 meters along strike. Historic intercepts had defined a potential resource and the current drilling program is confirming the historic information.

With these positive results, Dor? Copper has expanded the drilling program to approximately 16,500 meters to test the mineralization further along strike and up-dip from hole CB-21-32 and to test the extension of the West Vein and East Vein (subparallel to the Main Vein).

In the Main Vein above the dyke, Dor? Copper completed five holes to infill the deposit as part of the upcoming mineral resource estimate. An increase in mineral resources is expected based on the mineralization intersected in the holes; assay results are pending. Another five drill holes were completed to test the potential northern extension of the Main Vein below the dyke and Deep Main Vein Lens. No significant mineralization was intersected.

Figure 1 accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/91a1dd26-12ee-4e69-a8db-c9d13aa8cf02

Figure 2 accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/6624ac4b-1937-421f-a0de-e7637e1b8b81

Figure 3 accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/19c8bb04-bc8e-412c-aabf-32aca6a7feec

Table 1. Corner Bay Property Drill Assay Highlights from the 2021 Drill Program

1. The true width of the structures intersected is estimated at approximately 60% of the downhole width, except for holes CB-20-20, CB-20-21 to CB-21-24 where the orientation of the vein in the West Vein is yet to be properly determined. It is interpreted that the intercept in hole CB-21-26 is sub-parallel to the dip and therefore the true width is estimated at <30%.
2. Hole CB-20-20 was completed in 2021.

Table 2. 2020 Drill Assay Highlights from Main Vein below dyke (south)

1. True widths estimated to be 60-65% of downhole lengths.
   

Corner Bay Deposit

The Corner Bay deposit contains an Indicated resource of 1.35 Mt at an average grade of 3.01% Cu and 0.29 g/t Au, containing 89.8 million pounds of copper and 13,000 ounces of gold, and an Inferred resource of 1.66 Mt at an average grade of 3.84% Cu and 0.27 g/t Au, containing 140.3 million pounds of copper and 15,000 ounces of gold, assuming a cut-off grade of 1.5% Cu and a copper price of US$3.25 per pound (Technical Report dated June 2019).

The Corner Bay deposit is hosted by the intrusive Lac Dor? Complex on the southern flank of the Chibougamau anticline. A regional north-northeastern diorite dyke also cuts the area. Several significant shear zones oriented north-south and northwest-southeast have been identified in the area. The Corner Bay area is characterized by copper porphyry style mineralization and by copper mineralization in shear zones commonly associated with dykes related to the Chibougamau Pluton.

The Main Vein is oriented N10?W dipping 75 to 85 degrees towards the west. To the north, the Main Vein is limited by one of the NW-SE structures while to the south it is open at depth across the "La Chib" fault. The mineralization varies from 15 centimeters to 8 meters thick, with an average thickness of 2.2 meters, located within a shear zone varying in width from 2 to 25 meters. The Main Vein below the dyke to the south is thicker and higher grade that the Main Vein above the dyke. The Main Vein lateral extension is now more than 900 meters and it remains open at depth down-dip and along strike.

Drilling and Quality Control

The Company is using Miiken Drilling as the drilling contractor. Miiken is a joint venture between Chibougamau Diamond Drilling Ltd., the First Nations community of Ouje-Bougoumou and the First Nations community of Mistissini both located in the Eeyou Istchee territory.

Sample preparation and assays were done at SGS lab in Val-d'Or, Qu?bec. Samples were weighed, dried, crushed to 75% passing 2 mm, split 250 g, pulverized to 85% passing 75 microns. Samples were then fire assayed for Au (50 g) and sodium peroxide fusion ICP-MS finish for 34 elements.

QA/QC is done in house by Dor? Copper Geologists with oversight from the Exploration Manager. The check samples (blanks and standards - 4% of total samples with another 2% of core duplicates) that were inserted into the sample batches are verified against their certified values and are deemed a pass if they are within 3 standard deviations of the certified value. The duplicates are evaluated against each other to determine mineralization distribution (nugget). If there are large discrepancies in the check samples, then the entire batch is requested to be re-assayed.

Andrey Rinta, P.Geo., the Exploration Manager of the Corporation and a "Qualified Person" within the meaning of National Instrument 43-101, has reviewed and approved the technical information contained in this news release.

About Dor? Copper Mining Corp.

Dor? Copper Mining Corp. is a copper-gold explorer and developer in the Chibougamau area of Qu?bec, Canada. The Corporation is focussed on implementing its hub-and-spoke development strategy by advancing its key high-grade copper-gold brownfield projects towards a restart of operations. Our goal is to achieve an annual production of 60 million pounds of copper equivalent (or 100,000 ounces gold equivalent).

The Corporation has consolidated a large land package in the prolific Lac Dore/Chibougamau and Joe Mann mining camps that has produced 1.6 billion pounds of copper and 4.4 million ounces of gold. The land package includes 13 former producing mines, deposits and resource target areas within a 60-kilometre radius of the Company's 2,700 tpd mill (Copper Rand Mill).

Dor? Copper plans to deliver a preliminary economic assessment (PEA) of its hub-and-spoke model in late 2021. Currently, the Corporation is completing a 16,500-metre drilling program at its Corner Bay (Cu-Au) project which will lead to an updated mineral resource estimate in early Q3 2021. In addition, Dor? Copper is expected to have a maiden mineral resource estimate for the former producing Joe Mann mine (Au-Cu) by end of June 2021.

For further information, please visit the Corporation's website at www.dorecopper.com or refer to Dor? Copper's SEDAR filings at www.sedar.com or contact:

Cautionary Note Regarding Forward-Looking Statements
This news release includes certain "forward-looking statements" under applicable Canadian securities legislation. Forward-looking statements include predictions, projections and forecasts and are often, but not always, identified by the use of words such as "seek", "anticipate", "believe", "plan", "estimate", "forecast", "expect", "potential", "project", "target", "schedule", "budget" and "intend" and statements that an event or result "may", "will", "should", "could" or "might" occur or be achieved and other similar expressions and includes the negatives thereof. All statements other than statements of historical fact included in this release, including, without limitation, statements regarding the timing and ability of the Corporation to receive necessary regulatory approvals, and the plans, operations and prospects of the Corporation and its properties are forward-looking statements. Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable, are subject to known and unknown risks, uncertainties and other factors which may cause actual results and future events to differ materially from those expressed or implied by such forward-looking statements. Such factors include, but are not limited to, actual exploration results, changes in project parameters as plans continue to be refined, future metal prices, availability of capital and financing on acceptable terms, general economic, market or business conditions, uninsured risks, regulatory changes, delays or inability to receive required regulatory approvals, health emergencies, pandemics and other exploration or other risks detailed herein and from time to time in the filings made by the Corporation with securities regulators. Although the Corporation has attempted to identify important factors that could cause actual actions, events or results to differ from those described in forward-looking statements, there may be other factors that cause such actions, events or results to differ materially from those anticipated. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. The Corporation disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release.