Highlights of the updated Mineral Resource Estimate as of December 31, 2021 (the “2021 MRE”) include:

• Total Measured & Indicated Resources increased to 4.6 million tonnes at a grade of 11.0 g/t totalling 1.62 million ounces of gold, up 14% from last year.
• Total Inferred Resources increased to 4.6 million tonnes at a grade of 11.6 g/t totalling 1.70 million ounces of gold, up 41% compared to last year.
• The Company more than replaced the Mineral Resources it mined in 2021 representing the sixth consecutive year that it has, at a minimum, replaced the Mineral Resources mined at its Segovia Operations. El Silencio and Sandra K were the primary areas of growth within the 2021 MRE.
• The 2021 MRE continues to reaffirm confidence in the high-grade nature of the Segovia gold deposits which have been in continuous operation for more than 100 years.
• The brownfield exploration program, which focused on exploration for new resources at the brownfield exploration targets on the 24 veins within the Segovia mining title that are not currently in production, yielded its first addition in the 2021 MRE with inferred resources reported at the Vera Project.

The 2021 MRE reflects an increase in the diamond drilling database of 412 holes for 93,868 meters compared to December 2020. A new vein has been added to the Mineral Resource at the historical Vera mine, which includes an additional 63 holes for 9,640 meters (including 27 holes for 7,509 meters of new drilling), bringing the total cumulative drilling database to 2,553 holes for 378,846 meters. All diamond core drilling during 2021 has been logged and sent for preparation at the SGS laboratories in Medellin, with associated Quality Control Programs. In addition to the drilling, a total of 13,001 channel samples totalling some 11,485 meters in length were added to the database in 2021, including 4,588 channel samples totalling 3,326 meters from historical FGM sources, and 92 channels for 106 meters of GCM check sampling for Vera.

The 2021 MRE was prepared using a block model constrained with 3D wireframes of the principal veins, which have been sub-domained using high-grade mineralisation wireframes to constrain the influence of higher grade material. Assays are capped prior to compositing. Values were interpolated using ordinary kriging for well informed areas and inverse distance squared methodology for smaller veins with limited data. All models have been depleted using projections of the mining faces through the entire width of the veins. Classification has been applied based on a combination of data quality, confidence in the spatial location, and confidence in the mining depletion shapes. Only material reporting above a cut-off of 2.9 g/t over a minimum stope width of 1.0 m has been included in the 2021 MRE. The MRE for Las Verticales has not been updated as no new information is currently available and the previous estimate for this project remains valid.

Ben Parsons, Principal Consultant (Resource Geology) with SRK, prepared the Segovia MRE according to CIM Definition Standards and will be supported by a NI 43-101 independent report which will be published and filed on the Company’s website and SEDAR profile within 45 days. Mr. Parsons is a Qualified Person as defined by NI 43-101. The NI 43-101 independent report will include detailed information on the key assumptions, parameters and methods used to estimate the mineral resources.

Segovia’s Life-of-Mine (“LOM”) Mineable Gold Reserves Total Approximately 633,000 Contained Ounces Effective December 31, 2020

SRK has also completed preliminary results of an updated Preliminary Feasibility Study (“Segovia PFS”) for the Segovia Operations effective December 31, 2021 and is currently finalizing the technical report. At December 31, 2021, Segovia’s reported Mineral Reserve totaled approximately 745,000 proven and probable ounces of gold, based on 2.3 million tonnes of material at an average head grade of 10.1 g/t, compared with 633,000 ounces at the end of 2020 based on 2.2 million tonnes of material at an average head grade of 9.0 g/t.

For the Segovia PFS, SRK included the geological and resource modelling of the various deposits and mining areas that comprise the operating mine site of the Segovia Operations. A mining study and schedule was prepared by both SRK’s and the Company’s technical professionals to create a LOM production schedule, including both Company-operated areas and contractor-operated areas within the Company’s Providencia, El Silencio, Sandra K and Carla mines. The Segovia PFS production schedule includes only Proven and Probable Reserves, and as such, the annualized level of production over the seven-year projected mine life in the Segovia PFS may be lower than the Company’s current expectations. This is largely due to the exclusion of Inferred Resources in the LOM production schedule in the Segovia PFS which the Company currently mines and intends to continue mining in the future. In addition, the material processed under operating contracts at the Company’s Maria Dama plant from the small-scale mines located in the Company’s mining title is not included in the LOM production schedule in the Segovia PFS as it falls outside the Company’s mines and is therefore not included in the Company’s 2021 MRE or Mineral Reserves.

Fernando Rodrigues, BS Mining, MBA, MAusIMM, MMSAQP Practice Leader/Principal Consultant (Mining Engineer) with SRK, prepared the Segovia Mineable Reserve according to CIM Definition Standards and will be supported by a NI 43-101 independent report which will be published and filed on the Company’s website and SEDAR profile within 45 days. Mr. Rodrigues is a Qualified Person as defined by NI 43-101. The NI 43-101 independent report will include detailed information on the key assumptions, parameters and methods used to estimate the mineable reserve.

About GCM Mining Corp.

GCM Mining is a mid-tier gold producer with a proven track record of mine building and operating in Latin America. In Colombia, the Company is the leading high-grade underground gold and silver producer with several mines in operation at Segovia Operations. Segovia produced 206,000 ounces of gold in 2021. In Guyana, the Company is advancing its fully funded Toroparu Project, one of the largest undeveloped gold/copper projects in the Americas, which is expected to commence production of more than 200,000 ounces of gold annually in 2024. GCM Mining pays a monthly dividend to its shareholders and has equity interests in Aris Gold Corporation (44%; TSX: ARIS; Colombia – Marmato), Denarius Metals Corp. (27%; TSX-V: DSLV; Spain – Lomero-Poyatos and Colombia – Guia Antigua, Zancudo) and Western Atlas Resources Inc. (26%; TSX-V: WA: Nunavut – Meadowbank).

Additional information on GCM Mining can be found on its website at www.gcm-mining.com and by reviewing its profile on SEDAR at www.sedar.com.

Cautionary Statement on Forward-Looking Information:

This news release contains "forward-looking information", which may include, but is not limited to, statements with respect to mineral reserves and resources, LOM production, Segovia PFS financial data and other anticipated business plans or strategies. Often, but not always, forward-looking statements can be identified by the use of words such as "plans", "expects", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or "believes" or variations (including negative variations) of such words and phrases, or state that certain actions, events or results "may", "could", "would", "might" or "will" be taken, occur or be achieved. Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of GCM Mining to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Factors that could cause actual results to differ materially from those anticipated in these forward-looking statements are described under the caption "Risk Factors" in the Company’s Annual Information Form dated as of March 31, 2021 which is available for view on SEDAR at www.sedar.com. Forward-looking statements contained herein are made as of the date of this press release and GCM Mining disclaims, other than as required by law, any obligation to update any forward-looking statements whether as a result of new information, results, future events, circumstances, or if management’s estimates or opinions should change, or otherwise. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, the reader is cautioned not to place undue reliance on forward-looking statements.