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International Tower Hill Mines Provides Progress Report on Antimony Metallurgy Study at the Livengood Gold Project

Metallurgy & Processing

200 Burrard Street

Suite 1570

Vancouver, BC Canada

V6C 3L6

Tel: 604.683.6332

Fax: 604.408.7499

www.ithmines.com

NR25-06 September 4, 2025

International Tower Hill Mines Provides Progress Report on

Antimony Metallurgy Study at the Livengood Gold Project

Vancouver, British Columbia, September 4, 2025 – Intern ational Tower Hill Mines Ltd. (the “Company”) -

(TSX: ITH) (NYSE American: THM) today announced that it has received encouraging results from the first

phase of the metallurgical study on antimony mineralization at the Livengood Gold Project that was announced

on March 4, 2025.

The Company’s most recent S-K 1300 Technical Report Summary, “Pre-Feasibility Study of the Livengood

Gold Project”, as amended October 13, 2023, presented a new geologic model for the Livengood deposit and

detailed gold metallurgical work that allowed th e relationship between gol d recovery and antimony

mineralization to be characterized. During this geological modelling process, 54 veins of massive stibnite were

detailed as presented in Table 11-8 “Livengood deposit ma ssive stibnite grade estimates” of the S-K 1300

Technical Report Summary. While the pre-feasibility study detailed the 9.0 million ounce proven and probable

gold reserve contained within the 13.6 million ounce m easured and indicated gold resource, with 6.4 million

ounces of gold production projected over 21 years, no meta llurgical studies had been completed at that time

to provide an understanding of whether antimony might be recoverable from the massive stibnite veins.

Subsequent to the announcement on March 4, 2025, th e Company compiled four metallurgical composites,

each from individual veins, and provided splits from the composites to Advanced Mineral Technology

Laboratory Ltd., London, Ontario (AMTEL) for an timony deportment work. The gold and antimony assays

for these samples are presented in Table 1 below.

Table 1. Livengood Gold Project Vein Composite Assays

Sample Au g/mt Sb%

SB12 4.19 2.75

SB24 3.72 2.31

SB40 3.31 1.41

SB46 3.21 1.05

The samples were milled to p80 of 250 micron (the same grind size as selected in the 2023 Technical Report

Summary for the 9.0 million ounce proven and probable gold reserve based on optimization studies). The

milled material was separated by size and mineralogy and then examined. Results for all samples indicate that

the antimony is carried by stibnite, that most of the stibnite is of a floatable size (>10 micron), that the

liberation of stibnite is very good at the grind size of p80 250 micron, and thus the samples have the potential

to respond well to flotation.

These results warrant continuation into the next phase of the test work to assess potential flowsheets, to

evaluate how the samples respond to flotation, and to determine what the character istics of any concentrate

obtained might be. The Company intends to commence this work immediately at SGS Vancouver and SGS

Lakefield. The data presented here is very preliminary in nature and simply indicates a further examination of

the metallurgy of the antimony carried by the stibnite veins is warranted. Much more metallurgical and

extensive other work would be required before any determination of the recoverability of the antimony could

be established, as well as before any economic analysis or estimates of tonnage, grade or resource could be

developed.

International Tower Hill Mines Ltd. - 2 - September 4, 2025

NR25-06 Continued

Forward-Looking Statements

Statements in this press release that are not statements of historical or current fact constitute “forward-looking

statements” within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended,

Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of

1934, as amended, and “forward-looking information” w ithin the meaning of applicable Canadian securities

laws (collectively, “forward-looking statements”). Such forward-looking statements involve known and

unknown risks, uncertainties, and other factors that could cause the actual results of the Company to be

materially different from historical results or from an y future results expressed or implied by such forward-

looking statements. In addition to statements which explicitly describe such risks and uncertainties, readers are

urged to consider statements containing the terms “i ntends,” “estimates,” “may,” “might”, “will,” or other

similar expressions to be uncertain and forward-looking. Readers are cautioned not to place undue reliance on

these forward-looking statements, which speak only as of the date of this press release. The forward-looking

statements in this press release, including statements regarding estimates of the quality and quantity of the

mineral resources at the Livengood Gold Project, including gold and antimony, and the potential for production

at the Livengood Gold Project are based upon the Comp any’s current expectations and involve assumptions

that may never materialize or may prove to be incorrect . Actual results and the timing of events could differ

materially from those anticipated in such forward-looking statements as a result of various risks and

uncertainties, including, without limitation: (i) the dema nd for, and level and volatility of the price of, gold,

(ii) general business and economic conditions, (iii) the accuracy of the Company’s resource estimates

(including with respect to size and grade) and the geological, operational and price assumptions on which these

are based, (iv) the timing of the Company’s ability to commence and complete planned work programs at the

Livengood Gold Project, including the antimony study, (v) the Company’s ability to attract and retain key staff,

particularly in connection with th e permitting and development of any mi ne at the Livengood Gold Project,

and (vi) the Company’s ability to secure the necessary services and supplies on favorable terms in connection

with its programs at the Livengood Gold Project and ot her activities. The foregoing list of important factors

that could cause actual events to differ from expectations should not be construed as exhaustive and should be

read in conjunction with statements that are included herein and elsewhere, including the risk factors detailed

in the “Forward-Looking Statements,” “Risk Factor s” and “Management's Discussion and Analysis of

Financial Condition and Results of Operations” sections of the Company's Annual Report on Form 10-K for

the fiscal year ended December 31, 2024, Quarterly Report on Form 10-Q for the quarterly period ended March

31, 2025 and the Quarterly Report on Form 10-Q for th e quarterly period ended June 30, 2025 and other

documents that have been and will be filed by the Company from time to time with the Securities and Exchange

Commission and Canadian securities regulators. All forward-looking statements contained in this press release

speak only as of the date on which they were made . The Company undertakes no obligation to update such

statements to reflect events that occur or circumstances that exist afte r the date on which they were made,

except as required by applicable securities laws.

About International Tower Hill Mines Ltd.

International Tower Hill Mines Ltd. has a 100% interest in its Livengood Gold Project located along the paved

Elliott Highway, 70 miles north of Fairbanks, Alaska.

On behalf of

International Tower Hill Mines Ltd.

(signed) Karl L. Hanneman

Chief Executive Officer

Contact Information: Richard Solie, Jr., Manager - Investor Relations

E-mail: [email protected]

Direct line: 907-328-2825 Toll-Free: 1-855-428-2825