Excelsior Mining Corp. announced that it has filed a National Instrument 43-101 Technical Report dated effective February 1, 2023 on SEDAR at. The Report is with respect to the results of its Updated Preliminary Economic Assessment on the Johnson Camp Mine Heap Leach, located in Cochise County, southeastern Arizona that were originally announced in a February 22, 2023 news release.

The PEA considers the results of the drill program completed in 2022 and the implementation of sulfide leaching technology to improve recoveries. As part of the PEA, the Report also includes a repub publishing of the Prefeasibility Study Update on the North Star Deposit of the Gunnison Copper Project. The Gunnison Project is designed as a copper in-situ recovery mine using solvent extraction-electrowinning to produce copper cathode and the Johnson Camp mine is a conventional open pit and heap leach operation.

Results of the PFS and PEA disclosed in this press release are in United States dollars. JOHNSON CAMP HEAP LEACH PRELIMINARY ECONOMIC ASSESSMENT: Economic Analysis: The Johnson Camp Mine has historically been an open pit, heap leach operation since Cyprus Minerals opened the property in the 1970's. The operation includes two open pits, a two-stage crushing- agglomerating circuit, a fully functioning SX-EW plant capable of producing 25 million pounds of cathode copper per year, a complete set of PLS and raffinate ponds, and full infrastructure (ancillary facilities, access, power, water, and communications). Heap leaching of sulfide copper with accelerated pyrite oxidation is proposed in this PEA.

The Project plans include mining oxide, sulfide, and transition material from the Burro and Copper Chief pits for 20 years and heap leaching for an additional year to produce copper cathode at a capacity up to 25 million pounds per annum (mppa). To restart JCM for heap leaching, two developments need to take place simultaneously: pre-stripping and mine development, and the construction of a new heap leach pad, Pad 5. Both are considered to require between six and nine months to complete before irrigation of the new leach pad could commence. Piping of PLS and raffinate lines from Pad 5 to the JCM ponds also fits within this time frame.

A PEA has been completed by M3 with respect to this planned re-opening. 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. There is no certainty that the conclusions reached in the PEA will be realized.

Mineral resources that are not mineral reserves do not have demonstrated economic viability. Mineral Resources: The JCM copper resources were modeled and estimated using information provided by Excelsior under Mr. Bickel's supervision. The information is derived from historical core holes drilled by Cyprus Mining, Arimetco, Summo USA Corp., and Nord Resources Corp, and new drilling completed by Excelsior in 2022.

The drill hole database also includes analyses performed by Excelsior on the historical core. Total copper grades, as well as soluble copper ratios, were interpolated using inverse distance, ordinary kriging, and nearest-neighbor methods. The mineral resources reported herein were estimated by inverse distance interpolation as this method led to results that most appropriately reflected the drill data and geology of the deposit.

This is particularly true with respect to the estimation of the lowest-grade areas in the model, where potential over-estimation of volumes could materially impact the resource estimation at grades close to potential open-pit mining cut-offs. The nearest-neighbor estimation was completed for the purposes of statistical checking of the various estimation iterations. The pit shells created using these optimization parameters were used to constrain the project resources for comparison purposes.

An exclusion line was used to limit the pit optimization on the west side of the Burro Pit to prevent the pit optimizations from encroaching on the existing process plant and the historical leach pad. The in-pit resources were further constrained by the application of a cut-off of 0.1% CuT to all model blocks within the optimized pits. PEA Assumptions: The JCM plan has been developed based on a new mineral resource estimate for the Burro and Copper Chief deposits.

The mine plan targets the full resource at Johnson Camp over a 20-year period. A contract miner will be executing the mining of the pits and delivering material to the primary crusher. Mining of the deposit is expected to be accomplished with 100-ton haul trucks and front-end loaders.

Mining is planned on 20-ft bench heights. The pit configuration is double-benched with catch benches every vertical 40 ft. An annual schedule was developed for the mine plan.

Crushed and agglomerated material will be processed by placement on the newly permitted leach pad. This tonnage production is limited by the copper production capacity of the existing SX-EW plant of 25 million pounds of copper per year. The mining contractor is expected to be responsible for mine supervision, equipment operation, equipment maintenance, and blast hole drilling and loading.

The reference to specific equipment manufacturers is to illustrate equipment size and is not to be considered a recommendation. Production drilling is expected to be accomplished with Epiroc DM45 class drills or similar. Loading is expected to be accomplished with 14-yard CAT 992 class front-end loaders.

Haul trucks are planned to be CAT 777 class 100-ton trucks. The existing leach pads (Pads 1, 2 & 3) will not be used for future mining for new material extracted from the Burro and Copper Chief pits. The new leach pad area, Pad 5, is to be located northeast of the existing plant facility and is to be designed such that leach solutions flow by gravity into the new combined ILS- PLS pond located down slope of the new leach pad.

The PLS solution will be pumped back to the existing JCM SX-EW plant. A storm water pond is also provided. The Johnson Camp Mine is currently covered under Aquifer Protection Permit P-100514.

Excelsior has obtained a significant amendment to the existing APP to accommodate mining at JCM from the Burro Pit. A new facility, Leach Pad 5, with associated impoundments has been added to the existing APP to accommodate resumption of mining at JCM. The full capital cost for restarting the JCM heap leaching operation including mining pre-production, first fills/Owner's costs, leach pad construction, new leach pad stacking system, crusher and agglomeration refurbishment and haul road construction is approximately $58.9 million.

Staffing for the JCM project is mostly in place however several new hires will be needed to augment the existing staff.