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Osisko Development Announces Initial Mineral

Corporate Updates

NYSE: ODV TSXV: ODV NEWS RELEASE

________

1 Refer to Table 1 and 2 for a breakdown by resource category. Page 1 of 7

OSISKO DEVELOPMENT ANNOUNCES INITIAL MINERAL RESOURCE

ESTIMATE FOR TRIXIE, TINTIC PROJECT

213 koz of Gold grading 28.1 g/t and 385 koz of Silver grading 50.8 g/t in Measured and Indicated

Resources1

243 koz of Gold grading 19.6 g/t and 530 koz of Silver grading 42.8 g/t in Inferred Resources1

Montreal, Québec, January 17, 2023 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") is pleased to announce an initial mineral resource estimate ("MRE") for

its 100%-owned underground Trixie deposit ("Trixie") (the "Trixie MRE"), within the Company's wider Tintic

Project ("Tintic" or the "Tintic Project"), located in the historic East Tintic Mining District in central Utah,

U.S.A.

Chris Lodder, President of Osisko Development commented, "The initial Trixie MRE reflects a very limited

footprint of the historically defined mineralized zones at Trixie and was delineated within only six months of

the acquisition of the project. It exhibits outstanding precious metal grade potential within the structural

corridors of the host quartzite and based on all data received and compiled to date we see potential to

continue to extend mineralization at depth and on strike throughout and parallel to the historic mine footprint

as well as repeats at several other prospects and past producers in the East Tintic District. This resource

will assist the Company with its near-term exploration and operational planning."

TRIXIE MINERAL RESOURCE ESTIMATE

• The Trixie MRE comprises five mineralized zones within the greater Trixie deposit, including T1,

T2, T3, T4 and 75-85 zones over a strike length of 610 meters ("m"), a maximum width of 105 m

and to a maximum depth of 295 m.

• The Trixie MRE is based on 4,467 underground chip samples, 4,780.1 m of current and verified

historic drilling in 50 holes, of which 3,228.9 m of drilling in 23 holes were drilled by the Company

in 2022.

• Gold mineralization is associ ated with high sulphidation epithermal mineralization, structurally

controlled, and hosted within the quartzites. Mineralization consists of native Au, and ra re Au-Ag

rich telluride minerals with quartz and quartz-barite-sulphosalt stockwork veining.

Table 1: 2023 Trixie Mineral Resource Estimate (all zones) – January 10, 2023

Classification Tonnes

(000's)

Au Grade

(g/t)

Contained

Gold

(000's oz)

Ag Grade

(g/t)

Contained

Silver

(000's oz)

Measured 11 190.61 67 195.53 69

Indicated 225 20.17 146 43.73 316

Measured and Indicated 236 28.08 213 50.77 385

Inferred 385 19.64 243 42.82 530

Notes (applicable to Tables 1, 2, and 3)

1. Troy ounces ("oz"), gold ("Au"), silver ("Ag"), tonnes ("t"), grams per tonne ("g/t").

2. Effective date of the Trixie MRE is January 10, 2023.

3. The Company intends to file a technical report (the "Technical Report") in respect of the Trixie MRE in accordance with National

Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101") on SEDAR (www.sedar.com) and on EDGAR

(www.sec.gov) under Osisko Development's issuer profile within 45 days of the date of this news release.

4. Each of Mr. William Lewis P.Geo, of Micon International Limited and Alan S J San Martin, AusIMM(CP), of Micon International

Page 2 of 7

Limited (i) has reviewed and validated the Trixie MRE, (ii) is considered to be independent of the Company for purposes of

Section 1.5 of NI 43-101, and (iii) is a "qualified person" for purposes of NI 43-101.

5. The Trixie MRE is comprised of five zones within the greater Trixie area: T1, T2, T3, T4 and 75 -85. No blocks in the T3 meet

the cut-off grade used for the Trixie MRE.

6. The Trixie MRE disclosed in this news release were estimated using the CIM standards on mineral resources and reserves

definitions, and guidelines prepared by the CIM standing committee on reserve definitions and adopted by the CIM council.

7. Mineral Resources are reported when they are within potentially mineable shapes derived from a stope optimizer algorithm,

assuming an underground longhole stoping mining method with stopes of 6.1 m x 6.1 m x minimum 1.5 m dimensions.

8. Mineral resources are not mineral reserves and do not have demonstrated economic viability.

9. Geologic modelling was completed by Osisko Development senior production geologist Courtney Kurtz, P.G. of Utah, USA

using Leapfrog Geo software. The Trixie MRE was completed by Osisko Development Chief Resource Geologist, Daniel

Downton, P.Geo. using Datamine Studio RM Pro 1.12 software under the supervision of William Lewis and Alan San Martin of

Micon International Ltd.

10. The estimate is reported for an underground mining scenario and with USD assumptions. The cut -off grade of 4.85 g/t Au was

calculated using a gold price of US $1,750 per ounce, a CAD:USD exchange rate of 1.3 0; total mining, processing and G&A

costs of US$226.62 per imperial ton a combined royalty of 4.5% and an average metallurgical recovery of 95%.

11. Average bulk density values in the mineralized domains were assigned to the T1 (2.616 T/m3), T2 (2.955 T/m3), T3 (2.638 T/m3),

T4 (2.621 T/m3), and 75-85 (2.617 T/m3) domains.

12. Inverse Distance Squared interpolation method was used with a parent block size of 1.2 m x 1.2 m x 1.8 m.

13. The results of the Trixie MRE are presented in-situ. Calculations used metric units (metres, tonnes, g/t). The number of tonnes

is rounded to the nearest thousand. Any discrepancies in the totals are due to rounding effects.

14. Neither the Company nor Micon International Limited is aware of any known environmental, permitting, legal, title -related,

taxation, socio-political, marketing or other relevant issue that could materially affect the mineral resource estimate other than

disclosed in this news release.

Table 2: 2023 Trixie MRE Separated by Domain – January 10, 2023

Domain Category Tonnes Grade

(Au g/t)

Contained

Gold (oz)

Grade

(Ag g/t)

Contained

Silver (oz)

T1

Measured – – – – –

Indicated 34,470 16.39 18,159 30.55 33,856

M+I 34,470 16.39 18,159 30.55 33,856

Inferred 134,665 16.59 71,832 38.51 166,716

T2

Measured 10,938 190.61 67,029 195.53 68,757

Indicated 6,705 138.30 29,815 107.95 23,272

M+I 17,643 170.73 96,844 162.24 92,029

Inferred 25,181 101.37 82,070 146.32 118,457

T4

Measured – – – – –

Indicated 178,825 16.64 95,667 43.65 250,941

M+I 178,825 16.64 95,667 43.65 250,941

Inferred 128,038 9.10 37,460 21.64 89,063

75-85

Measured – – – – –

Indicated 4,870 14.10 2,207 51.77 8,106

M+I 4,870 14.10 2,207 51.77 8,106

Inferred 96,962 16.58 51,691 49.89 155,530

Total

Measured 10,938 190.61 67,029 195.53 68,757

Indicated 224,870 20.17 145,849 43.73 316,175

M+I 235,808 28.08 212,878 50.77 384,932

Inferred 384,845 19.64 243,053 42.82 529,766

Refer to notes described under Table 1, which are also applicable to Table 2 in their entirety.

Page 3 of 7

Table 3: Trixie MRE Cut-Off Grade ("COG") Sensitivity (Base Case in Bold) – January 10, 2023

Classification Tonnes COG Grade

(Au g/t)

Contained

Gold (oz)

Grade

(Ag g/t)

Contained

Silver (oz)

Measured +

Indicated

334,672 2.50 20.83 224,173 42.82 460,779

307,608 3.00 22.42 221,774 44.89 443,994

282,778 3.50 24.10 219,084 46.57 423,392

262,447 4.00 25.68 216,661 48.36 408,078

246,598 4.50 27.05 214,455 49.84 395,124

235,808 4.85 28.08 212,878 50.77 384,932

233,051 5.00 28.35 212,436 51.15 383,279

219,345 5.50 29.79 210,054 52.66 371,399

209,391 6.00 30.92 208,184 53.92 363,007

198,274 6.50 32.30 205,914 55.54 354,071

189,341 7.00 33.50 203,919 56.92 346,468

181,989 7.50 34.55 202,159 57.85 338,499

Inferred

553,279 2.50 14.75 262,371 38.22 679,912

493,696 3.00 16.19 256,945 39.98 634,610

450,545 3.50 17.42 252,276 41.35 598,941

420,273 4.00 18.37 248,242 42.24 570,717

397,456 4.50 19.18 245,047 42.52 543,387

384,845 4.85 19.64 243,053 42.82 529,766

379,046 5.00 19.87 242,188 43.02 524,210

361,726 5.50 20.56 239,154 43.98 511,444

347,256 6.00 21.18 236,435 44.95 501,843

329,274 6.50 21.97 232,593 46.19 488,985

313,378 7.00 22.74 229,161 47.45 478,092

296,008 7.50 23.63 224,925 48.87 465,129

Note: Micon has reviewed the COG used in the sensitivity analysis relating to the Trixie MRE and is of the opinion that the individual

cut-off grades used in the sensitivity analysis meet the test of reasonable prospects of economic extraction.

Table 4: Trixie MRE Cut-off Grade Calculation Breakdown

PARAMETERS VALUES

Mining Cost ($/ST) $60.00

G&A ($/ST) $64.97

Haulage ($/ST) $10.00

Milling ($/ST) $89.00

Total Refining Cost $2.65

Gold Price $1,750

Royalty (Combination) 4.50%

Mill Recovery 95.0%

Cut-off Grade (COG) 4.85

Page 4 of 7

TRIXIE TEST MINE OPERATIONAL ACTIVITIES

• Approximately 50% of the 1,390 meter (4,550 ft.) Trixie portal underground decline ramp has been

completed to date. On track to reach the 625 level by the second quarter of 2023.

• The decline will significantly improve access to the underground workings, expand potential

underground exploration target areas and provide sufficient flexibility to complete additional

programs targeting mineral resource growth potential beyond the 625 level.

• Excavation of deeper underground levels is anticipated to continue in the second half of 2023 and

beyond, to facilitate deployment of mechanized mining equipment and to increase the overall

potential mining rate capacity of the operation currently constrained by a single shaft.

• Target to ramp up processing capacity to 500 short tons per day by the end of 2023.

• To achieve higher operating rates, certain existing processing infrastructure at the Burgin mill will

need to be upgraded and/or amended, including the construction of a new mill facility to support

higher processing rates.

• During this time, it is anticipated that VAT leach processing and certain small scale underground

test mining activities will be temporarily suspended while the Company focuses its efforts on fast

tracking the mill expansion, accelerating decline development, and refurbishing existing surface

and underground infrastructure in preparation for higher operating rates.

• Underground activities will continue to focus on exploration development along the 625 level to the

Sioux-Ajax Fault, following identified mineralized zones, and on building a stockpile of mineralized

material to provide operational flexibility during the commissioning phase of the upgraded mill

facility.

• The Company expects to advance rehabilitation of the Trixie shaft and the 750 level to allow for

further underground sampling and diamond drilling. There are currently two underground diamond

drills operating on the 625 level.

Qualified Persons

The scientific and technical information contained in this news release has been reviewed and approved

by Maggie Layman, P.Geo., Vice President, Exploration of Osisko Development, and a " qualified person"

("QP") within the meaning of NI 43-101.

The independent QPs for the Trixie MRE, as defined by NI 43-101, are William Lewis, P.Geo. and Alan S.

J. San Martin AusIMM(CP) of Micon International Limited. Each of the QPs is independent of Osisko

Development and has reviewed and approved the content in this news release.

Quality Assurance (QA) – Quality Control (QC)

True width determination is estimated to be approximately 0.3 m to 2.4 m (1 to 8 ft.) wide for the T2 structure

and approximately 3 m to 25 m (10 to 80 ft.) for the T4 mineralized stockwork zone located in the hanging

wall of the T2 structure. All underground face samples are collected by TCM geologists from each of the

active mining faces, with samples transported by the geologists from Trixie to the on -site TCM laboratory

located at the Burgin administrative complex. Underground samples are dried, crushed to <10 mm and a

250 g split is taken. The split is pulverized, and a 30 g Fire Assay with gravimetric finish is completed to

determine gold and silver grades, reported in oz/short ton and g/t.

The TCM Burgin laboratory is not a certified analytical laboratory, however, the facility is managed by a

qualified Laboratory Manager with annual auditing by technical staff. Inter -laboratory check assays using

ALS Laboratory as a third-party independent analysis of samples is routinely carried out as part of ongoing

Quality Assurance-Quality Control ("QA/QC") work. Certified OREAS QC standards and blanks are inserted

at regular intervals in the sample stream to monitor laboratory performance.

All drill core and exploration samples are dispatched to ALS Laboratory for offsite sample preparation and

analysis. Samples are assigned a unique sample ID. All geological and sampling information is entered into

Datamine Fusion database. Core is sawn in half and half are sampled. Certified standards and blanks

inserted into all sample dispatches. Samples are collected by Old Dominion Transportation and dispatched

Page 5 of 7

to ALS Laboratory in Reno, NV. Sample submission forms accompany the samples, and digital copies

emailed to ALS.

All sample preparation is completed by ALS, including crushing and pulverizing (Prep31) of samples.

Analytical assays include gold and silver by fire assay of 50 g sample with AAS finish (Au-AA26), over limits

by gravimetric analysis (Au -Grav22). Multi element analysis is by four acid digest (ME -MS61). The pulps

are returned to Osisko Development and coarse rejects are disposed after 90 days. Assays are reported

to Osisko Development, and then loaded into Datamine Fusion, QA/QC samples are checked, and assays

merged with sample information for future reporting.

About Osisko Development Corp.

Osisko Development Corp. is a premier North American gold development company focused on high-quality

past-producing properties located in mining friendly jurisdictions with district scale potential. The Company's

objective is to become an intermediate gold producer by advancing its 100%-owned Cariboo Gold Project,

located in central B.C., Canada, the recently acquired Tintic Project in the historic East Tintic mining district

in Utah, U.S.A., and the San Antonio Gold Project in Sonora, Mexico. In addition to considerable brownfield

exploration potential of these properties, that benefit from significant historical mining data, existing

infrastructure and access to skilled labour, the Company's project pipeline is complemented by other

prospective exploration properties. The Company's strategy is to develop attractive, long -life, socially and

environmentally sustainable mining assets, while minimizing exposure to development risk and growing

mineral resources.

For further information, please contact Osisko Development Corp.:

Sean Roosen Philip Rabenok

Chairman and CEO Director, Investor Relations

Email: [email protected] Email: [email protected]

Tel: +1 (514) 940-0685 Tel: +1 (437) 423-3644

CAUTIONARY STATEMENTS

Cautionary Statement Regarding Estimates of Mineral Resources

This news release uses the terms measured, indicated and inferred mineral resources as a relative measure of the

level of confidence in the resource estimate. Readers are cautioned that mineral resources are not min eral reserves

and that the economic viability of resources that are not mineral reserves has not been demonstrated. The mineral

resource estimate disclosed in this news release may be materially affected by geology, environmental, permitting,

legal, title, socio-political, marketing or other relevant issues. The mineral resource estimate is classified in accordance

with the Canadian Institute of Mining, Metallurgy and Petroleum's "CIM Definition Standards on Mineral Resources and

Mineral Reserves" incorporated by reference into NI 43-101. Under NI 43-101, estimates of inferred mineral resources

may not form the basis of feasibility or pre -feasibility studies or economic studies except for preliminary economic

assessments. Readers are cautioned not to assume that further work on the stated resources will lead to mineral

reserves that can be mined economically.

Cautionary Statement Regarding Test Mining Without Feasibility Study

The Company cautions that the decision to commence small-scale underground mining activities and batch vat leaching

at the Trixie test mine has been made without the benefit of a feasibility study, or reported mineral resources or mineral

reserves, demonstrating economic and technical viability, and, as a result there may be increased uncertainty of

achieving any particular level of recovery of material or the cost of such recovery. The Company cautions that

historically, such projects have a much higher risk of economic and technical failure. There is no guarantee tha t

production will continue as anticipated or at all or that anticipated production costs will be achieved. The failure to

continue production may have a material adverse impact on the Company's ability to generate revenue and cash flow

to fund operations. Failure to achieve the anticipated production costs may have a material adverse impact on the

Company's cash flow and potential profitability. In continuing current operations at Trixie after closing, the Company

will not be basing its decision to continue such operations on a feasibility study, or reported mineral resources or mineral

Page 6 of 7

reserves demonstrating economic and technical viability. The Company cautions that mining at Trixie could be

suspended at any time.

Cautionary Statement to U.S. Investors

The Company is subject to the reporting requirements of the applicable Canadian securities laws, and as a result

reports information regarding mineral properties, mineralization and estimates of mineral reserves and mineral

resources, including the information in the Tintic Technical Report and this news release, in accordance with Canadian

reporting requirements, which are governed by NI 43 -101. As such, such information concerning mineral properties,

mineralization and estimates of mineral reserves and mineral resources, including the information in the Tintic Technical

Report and this news release, is not comparable to similar information made public by U.S. companies subject to the

reporting and disclosure requirements of the U.S. Securities and Exchange Commission ("SEC").

FORWARD LOOKING STATEMENTS

Certain statements contained in this news release may be deemed "forward-looking statements" within the meaning

of the United States Private Securities Litigation Reform Act of 1995 and "forward-looking information" within the

meaning of applicable Canadian securities legislation. These forward ‐looking statements, by their nature, require

Osisko Development to make certain assumptions and necessarily involve known and unknown risks and uncertainties

that could cause actual results to differ materially from those expressed or implied in these forward‐looking statements.

Forward‐looking statements are not guarantees of performance. Words such as "may", "will", "would", "could",

"expect", "believe", "plan", "anticipate", "intend", "estimate", "continue", or the negative or comparable terminology, as

well as terms usually used in th e future and the conditional, are intended to identify forward ‐looking statements.

Information contained in forward‐looking statements is based upon certain material assumptions that were applied in

drawing a conclusion or making a forecast or projection, including management's perceptions of historical trends,

current conditions and expected future development s; the utility and significance of historic data, including the

significance of the district hosting past producing mines; the unique mineralization at Trixie; the potential of high grade

gold mineralization on Trixie; the results (if any) of further exploration work to define and expand mineral resources ;

the ability of exploration work (including drilling) to accurately predict mineralization; the ability to generate additional

drill targets; the ability of management to understand the geology and potential of Trixie; the timing and ability of the

Company to produce the Trixie MRE (or any subsequent MRE) (if at all); the information and the scope of t he

contemplated Trixie MRE (and any subsequent MRE); the impact of the Trixie MRE; the ability of the Company to

complete its exploration objectives in 2023 in the timing contemplated (if at all); the ongoing advancement of the Trixie

decline; the deposit remaining open for expansion at depth and down plunge ; the ability to realize upon any

mineralization in a manner that is economic; as well as other considerations that are believed to be appropriate in the

circumstances, and any other information herein t hat is not a historical fact may be "forward looking information ".

Material assumptions also include, management's perceptions of historical trends, the ability of exploration (including

drilling) to accurately predict mineralization, budget constraints an d access to capital on terms acceptable to the

Company, current conditions and expected future developments, results of further exploration work to define or expand

any mineral resources, the ability to continue production at Trixie, as well as other considerations that are believed to

be appropriate in the circumstances. Osisko Development considers its assumptions to be reasonable based on

information currently available, but cautions the reader that their assumptions regarding future events, many of which

are beyond the control of Osisko Development, may ultimately prove to be incorrect since they are subject to risks

and uncertainties that affect Osisko Development and its business. Such risks and uncertainties include, among

others, risks relating to capital market conditions and the Company's ability to access capital on terms acceptable to

the Company for the contemplated exploration and development at Tintic ; the ability to continue current operations

and exploration; regulatory framework; the ability of exploration activities (including drill results) to accurately predict

mineralization; errors in management 's geological modelling; the ability to expand operations or complete further

exploration activities, including drilling; property and stream interests in the Tintic Project; the ability of the Company

to obtain required approvals; the results of exploration activities; risks relating to exploration, development and mining

activities; the global economic climate; metal prices; dilution; envi ronmental risks; and community and non -

governmental actions and the responses of relevant governments to the COVID-19 outbreak and the effectiveness of

such responses. Readers are urged to consult the disclosure provided under the heading "Risk Factors " in the

Company's annual information form for the year ended December 31, 2021, as amended, which has been filed on

SEDAR (www.sedar.com) under Osisko Development 's issuer profile and on the SEC 's EDGAR website

(www.sec.gov), for further information regarding the risks and other factors applicable to the exploration results.

Although the Company's believes the expectations conveyed by the forward-looking statements are reasonable based

on information available at the date of preparation, no assurances can be g iven as to future results, levels of activity

and achievements. The Company disclaims any obligation to update any forward -looking statements, whether as a

result of new information, future events or results or otherwise, except as required by law. There can be no assurance

that these forward -looking statements will prove to be accurate, as actual results and future events could differ

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materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-

looking statements.

Neither the 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. No

stock exchange, securiti es commission or other regulatory authority has approved or disapproved the

information contained herein.