Mineral Reserves and Resources

–

MINERAL RESOURCE ESTIMATE
The Trixie mineral resource estimate (“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.

2023 Trixie MRE Separated by Domain – January 10, 2023

Notes:

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 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’s senior production geologist Courtney Kurtz, P.G. of Utah, USA using Leapfrog Geo software. The Trixie MRE was completed by Osisko Development’s Chief Resource Geologist, Daniel Downton, P.Geo. using Datamine Studio RM Pro 1.12 software. The Trixie MRE was reviewed and verified by 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 1.30; 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.

Technical Report

–