Mr. Eric Jones reports

THUNDER MOUNTAIN GOLD, INC. UPDATED 43-101 MINERAL RESOURCE ESTIMATE AT SOUTH MOUNTAIN SHOWS SIGNIFICANT INCREASE

Thunder Mountain Gold Inc. has filed a National Instrument 43-101 mineral resource estimate (MRE) incorporating results from surface diamond drilling program conducted in 2021 at the South Mountain project in southwestern Idaho, United States. The updated NI 43-101 MRE includes an increased resource for the project while maintaining the high-grade mineralization.

The updated, independent NI 43-101 MRE, which has an effective date of Oct. 16, 2023, was prepared in accordance with National Instrument 43-101 -- Standards of Disclosure for Mineral Projects by Hard Rock Consulting LLC, based in the U.S. More details are included in the table entitled "South Mountain mineral resource statement (U.S. units)."

Highlights of updated mineral resource:

• Measured and indicated (M&I): 223,000 tons grading 9.02 per cent zinc (Zn), 4.27 ounces per ton (oz/ton) silver (Ag), 0.059 oz/ton gold (Au), 0.64 per cent copper (Cu) and 0.94 per cent lead (Pb).
• This represents a 7.7-per-cent increase to the M&I tonnage from the previous 2021 NI 43-101 MRE, with an 18.82-per-cent Zn equivalent grade (ZnEq) or a 20.55 oz/ton Ag equivalent grade (AgEq).
• Inferred: 959,000 tons grading 7.56 per cent Zn (14-per-cent increase in Zn pounds (lb)), 5.67 oz/ton Ag (14.10-per-cent increase in Ag ounces), 0.037 oz/ton Au (3.3-per-cent increase in Au ounces), 0.80 per cent Cu (14.5-per-cent increase in Cu lb) and 1.06 per cent Pb (25.4-per-cent increase in Pb lb).
• This represents a 15.1-per-cent increase in the inferred tonnage from the previous 2021 NI 43-101 MRE, with a 17.2 per cent ZnEq or a 19.30 oz/ton AgEq.
• The DMEA zone in the model was extended an additional 250 feet down dip and remains open.

"We are extremely pleased by the results of the revised NI 43-101 MRE. These deep surface core holes placed to determine the continued down-dip potential of the mineralization displayed positive results on our resource. Our independent engineering firm -- Hard Rock Consulting LLC -- did a great job with the data. This new data supports previously reported model and results confirming the continuation of all mineralized zones extending down plunge, and that they continue to remain open at depth," commented Eric T. Jones, president and chief executive officer of Thunder Mountain Gold. "It is still our opinion that South Mountain has the potential to be one of the lowest-cost producers of zinc, silver and gold in North America."

Mineral resource estimate

This latest round of drilling completed during the late fall of 2021 proves the continuation of the down-plunge extension of the DMEA zone at depth. This zone remains open in both directions. All of the drill results have now been incorporated into the updated NI 43-101 MRE for the South Mountain deposit. The increase in measured and indicated tons is the result of updated metal prices and mining costs. Surface drilling completed in 2021 accounts for approximately 8 per cent of the increase in inferred tons, while the remaining 7-per-cent increase is due to updated metal prices and mining costs.

The table entitled "South Mountain mineral resource statement (U.S. units)" provides the mineral resource statement for the project in United States units, with details of the modelling methodology and cut-off grades applied to the mineral resource. The historical technical report for the mineral resource estimate for the South Mountain project, Owyhee county, Idaho, U.S., dated June 15, 2021, is filed on SEDAR+.

Qualified person statement for the mineral resource estimate

Richard A. Schwering, PG, SME-RM, a resource geologist with Hard Rock Consulting, is responsible for the South Mountain project mineral resource estimate with an effective date of Oct. 16, 2023. Mr. Schwering is a qualified person as defined by National Instrument 43-101 and is independent of Thunder Mountain Gold and South Mountain Mines Inc. Mr. Schwering estimated the mineral resources based on drill hole and channel sample data constrained by geologic boundaries using an ordinary krige algorithm. The geologic model and mineral resource estimate were completed using Leapfrog Geo software version 2023.1.1. Hard Rock Consulting also completed the previous resource estimate.

Quality assurance and quality control procedures

The project employs a rigorous QA/QC program that includes blanks, duplicates and appropriate certified standard reference material. All samples are introduced into the sample stream prior to sample handling/crushing to monitor analytical accuracy and precision. The insertion rate for the combined QA/QC samples is 10 per cent or more, depending upon batch sizes. ALS Global completed the analytical work, with the core samples processed at its preparation facility in Reno, Nev., U.S. All analytical and assay procedures are conducted in the ALS facility in North Vancouver, B.C. The samples are processed by the following methods, as appropriate, to determine the grades: Au-AA23 Au 30-gram fire assay with AA (atomic absorption) finish; ME-ICP61 33-element four-acid digest with ICP-AES (inductively coupled plasma atomic emission spectroscopy) finish; ME-OG62 ore-grade elements, four-acid with ICP-AES finish; Pb-OG62 ore-grade Pb, four-acid with ICP-AES finish; Zn-OG62 ore-grade Zn, four-acid digestion with ICP-AES finish; Ag-GRA21 Ag 30 g fire assay with gravimetric finish.

The technical information in this news release has been reviewed and approved by Mr. Schwering, SME-RM, PG, principal resource geologist, Hard Rock Consulting, a qualified person as defined by National Instrument 43-101.

The South Mountain project

The South Mountain mine is a polymetallic development project containing high-grade zinc, silver, gold and copper, and is located approximately 70 miles southwest of Boise, Idaho. The project was intermittently mined from the late 1800s to the late 1960s, and its existing underground workings remain intact and well maintained. Thunder Mountain Gold purchased and advanced the project from 2007 through 2022, with expenditures into the project of approximately $20-million (U.S.). Historic production at the project has largely come from high-grade massive sulphide bodies that remain open at depth and along strike. According to historical smelter records, approximately 53,642 tons of mineralized material has been mined to date. These records also indicate average grades: 14.5 per cent Zn, 10.6 oz/ton Ag (363.42 grams per tonne (g/t) Ag), 0.058 oz/ton Au (1.98 g/t Au), 1.4 per cent Cu and 2.4 per cent Pb were realized. See the NI 43-101 technical report, available on SEDAR+ and the company's website, entitled "Updated mineral resource estimate for the South Mountain project," dated Dec. 15, 2023, for more details.

About Thunder Mountain Gold Inc.

Thunder Mountain Gold, a junior exploration company founded in 1935, owns interests in base and precious metals projects in the western U.S. The company's principal asset is the South Mountain mine, a historic former producer of zinc, silver, gold, lead and copper, located on private land in Owyhee county, Idaho. Thunder Mountain Gold also owns 100 per cent of the Trout Creek project -- a gold exploration project located along the western flank of the Shoshone Mountain Range in the Reese River valley, adjacent to and surrounded by Nevada Gold Mines, a joint operating agreement between Barrick and Newmont Gold Inc..

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