Osisko Updates Canadian Malartic Mine Plan

MONTREAL, QUEBEC--(Marketwired - March 20, 2014) - Osisko Mining Corporation (TSX:OSK)(FRANKFURT:EWX) ("Osisko") is pleased to provide an updated summary of the annual mine production plan for its 100%-owned Canadian Malartic mine. This new plan is based on the recently disclosed reserve estimate of 9.37M ounces gold using a gold price of US$1,300 per ounce (see Osisko March 12, 2014 press release). All Canadian dollar figures are based on an exchange rate of 1.10.

Highlights

• Canadian Malartic proven & probable in-pit reserves of 9.37 million ounces
• Mine life of 14.2 years based on a 55,000 tonnes per day (tpd) milling rate
• Average gold production of 610,000 ounces per year over the next five years (2014-2018) at cash costs of US$516 per ounce
• Average of 597,000 ounces per year gold production over life of mine at cash costs of US$525 per ounce
• Average head grade of 1.09 g/t over the next five years, and 1.03 g/t over the mine life
• Average metallurgical recovery of 89.2% over the mine life
• Recoverable gold of 8.4 million ounces over the mine life
• Life of mine sustaining capital of C$628 million
• Life of mine development capital of C$233 million
• Life of mine capitalized stripping of C$188 million
• Discounted after-tax net cash flows of C$3,141 million over life of mine

Sean Roosen, President and CEO, noted: "We are very pleased to present our shareholders with this updated mine plan based on the latest engineered pit and reserve estimate of 9.37 M ounces gold. Not only has the latest reserve estimate demonstrated the robust nature of the Canadian Malartic deposit at US$1300 gold, but this updated mine plan thoroughly demonstrates Canadian Malartic's strong production profile and exceptional value. With life of mine average gold production of 597,000 ounces, cash costs of US$525 per ounce and location in one of the world's premier jurisdictions, it is abundantly clear that Canadian Malartic is a world class low-cost gold mine. This flagship asset will produce strong free cash flow for a long time for the benefit of our shareholders."

The key inputs and conclusions from the new mine plan are as follows:

		First 5 Years	Life of Mine
Economic Assumptions
Gold Price	US$/oz	1,350	1,350
Canadian Dollar Rate		1.10	1.10
Electricity	cents/kWh	0.044	0.044
Oil	US$/bbl	100	100
Fuel	C$/l	0.99	0.99
Income/Mining Tax Rates	%	26.9 / 17.2	26.9 / 17.7
Royalty Rate	%	1.13	0.81
Operational Parameters
Strip Ratio	W:O	2.10	2.09
Average Processed Gold Grade	g/t	1.09	1.03
Metallurgical Recovery	%	89.0	89.2
Average Annual Gold Production	000's oz	610	597
Mine Life	Years	na	14.2
Operating Costs
Cash Costs	C$/oz	$568	$577
Cash Costs	US$/oz	$516	$525
All-in Sustaining Costs	US$/oz	na	$691
All-in Costs	US$/oz	na	$717
LOM Capital Costs
Sustaining Capital	C$ M	$628
Development Capital	C$ M	$233
Capitalized Stripping	C$ M	$188

Canadian Malartic Proven & Probable Reserves

The open pit Proven & Probable gold reserves now stand at 9.37 million (M) ounces at a fully diluted average gold grade of 1.04 grams per tonne ("g/t Au"), following total 2013 production of 475,277 ounces of gold. Total precious metal production from the beginning of operations in April 2011 to December 31, 2013 was 1,044,388 ounces gold and 753,776 ounces silver. Global Measured and Indicated (M&I) resources stand at 11.10 M ounces gold, and global Inferred resources stand at 1.16M ounces gold. The global in situ 2014 resources include reserves but exclude 2014 production to date.

Reserve estimates using base case US$1,300 engineered pit design with lower cut-off grade of 0.33 g/t Au

Sector	Tonnes (M)	Grade (g/t)	Au (M oz)
Canadian Malartic
Proven Reserves	45.5	0.85	1.25
Probable Reserves	140.0	1.02	4.60
Proven & Probable Reserves	185.5	0.98	5.85
Barnat*
Proven Reserves	12.1	1.35	0.52
Probable Reserves	69.8	1.20	2.70
Proven & Probable Reserves	81.9	1.22	3.22
Gouldie + Jeffrey*
Proven Reserves	5.88	0.70	0.13
Probable Reserves	5.41	0.73	0.13
Proven & Probable Reserves	11.3	0.71	0.26
Stockpiles
Proven Reserves	2.47	0.52	0.04
Probable Reserves	0.00	0.00	0.00
Proven & Probable Reserves	2.47	0.52	0.04
TOTAL
Proven Reserves	65.9	0.92	1.94
Probable Reserves	215.3	1.07	7.43
Proven & Probable Reserves	281.2	1.04	9.37

*	Barnat and Jeffrey represent portions owned by Osisko and exclude Abitibi Royalties attributable ownership.

Mining & Production

The life of mine strip ratio is estimated at 2.09.

In terms of mine sequencing, the current life of mine plan contemplates mining of the Barnat zone in 2017, with pre-strip operations commencing mid-2015, with mining of the Gouldie zone commencing in 2014 and mining of the Jeffrey zone commencing in 2017.

Mining rates are expected to average 202,000 tpd in 2014, with a peak of 217,000 tpd in 2017.

The haul truck fleet is expected to grow by 3 trucks in 2016, to reach a peak of 28 during the mining of the Barnat zone. All the loading equipment required to mine the Barnat zone was added in 2012 and 2013, and therefore no further loading equipment is required.

Processing

Mine life is estimated at 14.2 years, based on a 55,000 tonnes per day (tpd) milling rate, assuming 92% availability. Average life of mine metallurgical recovery is estimated to be 89.2%.

A summary of the annual mine production plan is outlined in the following table:

Annual Mine Production Estimates¹

Period	Ore Mined	Waste Mined	Strip Ratio	Ore Milled	Grade	Attributable Processed Gold	Recovery		Attributable Recovered Gold
	(Kt)	(Kt)		(Kt)	(g/t)	(Koz)	(%)		(Koz)
2014	20,153	53,884	2.67	18,533	1.00	598	89.0	%	532
2015	24,495	54,003	2.20	20,075	1.04	669	88.5	%	592
2016	27,021	52,339	1.94	20,130	1.09	708	89.1	%	631
2017	26,475	48,982	1.85	20,075	1.05	664	88.6	%	588
2018	23,586	46,148	1.96	20,075	1.24	785	89.7	%	704
2019	25,450	36,430	1.43	20,075	1.06	687	89.5	%	615
2020	20,589	40,977	1.99	20,130	0.89	576	88.4	%	509
2021	17,195	42,279	2.46	20,075	1.01	650	88.9	%	578
2022	23,618	38,027	1.61	20,075	0.95	613	89.0	%	546
2023	20,990	38,966	1.86	20,075	1.34	857	88.9	%	762
2024	14,270	42,384	2.97	20,130	1.01	644	89.7	%	578
2025	14,676	40,966	2.79	20,075	1.04	670	89.8	%	602
2026	14,810	40,760	2.75	20,075	1.08	697	90.3	%	629
2027	7,469	11,606	1.55	20,075	0.78	504	88.6	%	447
2028	--	--	--	3,594	0.44	51	85.5	%	44
Total/avg	280,797	587,751	2.09	283,267	1.03	9,373	89.1	%	8,356

1	Mill feed in a given year may include stockpiled ore. Exclusive of Abitibi Royalties' attributable portions of Barnat and Jeffrey, representing 44koz of processed gold.

Operating Costs

Cash costs over the life of mine are estimated to average US$525 per ounce, or C$577 per ounce. All-in-sustaining costs for Canadian Malartic are expected to be US$691 per ounce or C$760 per ounce, with all-in costs at Canadian Malartic expected to be US$717 per ounce or C$788 per ounce, as defined by the World Gold Council.

Life of Mine Cash Costs
	C$ / tonne milled	C$ / tonne mined	C$ / ounce
Mining Costs	7.61	2.48	258
Processing Costs	8.05	--	273
General & Administration	2.17	--	73
Total before adjustments	17.83	2.48	604
Refining & Transport	--	--	3
By-product Credits	--	--	(19	)
Capitalized Stripping	--	--	(23	)
Royalties	--	--	12
Total	--	--	577

Capital Costs

Life of mine Sustaining capital is expected to total C$628 million, including mill and mine maintenance, mining equipment purchase, mining fleet major component replacement and tailings management.

Life of mine development capital is expected to total C$233 million, which includes:

• Expenditure of C$157 million for topographic drilling, overburden removal and pre-shear drilling of bench walls.
• Road deviation (Route 117): C$61 million.
• Mill capital projects: C$15 million.

Life of mine capitalized stripping activities costs are expected to be C$188 million.

Economic Analysis

The cash flow model for Canadian Malartic is based on a gold price of US$1,350 per ounce and a Canadian dollar exchange rate of 1.10. Based on these parameters, the Canadian Malartic mine is expected to produce pre-tax cash flow of C$6,516 million and after-tax cash flow of C$4,388 million, inclusive of income and mining taxes.

Using a discount rate of 5%, Canadian Malartic generates discounted pre-tax net cash flows of C$4,551 million and after-tax net cash flows of C$3,141 million. This figure excludes the potential for tax savings using existing tax pools at Osisko's other subsidiaries (other Canadian projects) as well as potential tax synergies from the future development of these projects.

5% NPV Sensitivity to Gold Price
Gold Price (US$/oz)	5% After-Tax NPV
$1,350	C$3,141
$1,500	C$3,702
$2,000	C$5,556

The following table summarizes the value of Canadian Malartic (excluding all of Osisko's other assets) based on consensus P/NAV multiples:

Company	P/NAV(1)	Implied Canadian Malartic Value Per Share
Agnico Eagle	1.7x	$12.16
Barrick	1.6x	$11.44
Goldcorp	1.5x	$10.73
Newmont	1.5x	$10.73
New Gold	1.3x	$9.30
Randgold	1.3x	$9.30
Yamana	1.2x	$8.58
Kinross	1.2x	$8.58
Average	1.4x	$10.10

(1)

P/NAV multiple represents current share price divided by broker consensus net asset value per share (NAVPS) for each company. NAVPS is calculated as the median NAVPS for all or most of all equity research analysts that provide coverage to the company. The NAVPS calculations underlying the above are drawn from the median analysts' report for each company. We note that the companies noted above may have different geographic and operational portfolios. We also note that each such report may include different assumptions for the balance sheet position of the company, discount rate and gold price underlying the NAVPS calculation. These calculations, and the inputs, may not be directly comparable to the basis for the calculation of NAVPS undertaken for Osisko.

2014 Outlook

Mill throughput is expected to stabilize at approximately 55,000 tonnes per day in 2014 with the completion of optimization programs currently in progress. Together with increased contribution from higher grade material in the now accessible northern pit wall, it is anticipated that gold production for the current year will increase to between 525,000 to 575,000 ounces (an increase of 11% to 21% over record 2013 production of 475,277 ounces gold).

Cash costs per ounce are estimated between C$580 and C$635, a 24% to 16% reduction in costs from 2013. Cash costs per ounce in US dollars are estimated at US$527 to US$577 using an exchange rate of 1.10.

Capital expenditures for 2014 are estimated at C$148.0 million:

(In millions Canadian of dollars)
Canadian Malartic(1)	125.8
Exploration and evaluation - capitalized	22.2
Capital Expenditures	148.0

(1)	Includes C$65.6 million related to stripping and pit preparation activities.

Conference Call Information

Osisko will host a conference call on Thursday, March 20, 2014 at 9:00 EDT, where senior management will discuss the updated mine plan and provide an update of the Company's activities. Those interested in participating in the conference call should dial in approximately five to ten minutes before the start of the conference to allow ample time to access at 1-416-981-9000 (Toronto local and international), or 1-800-893-0176 (North American toll free). An operator will direct participants to the call.

The conference call replay will be available from 11:00 EDT on March 20, 2014 until 23:59 EDT on April 3, 2014 with the following dial in number: 1 416 626 4100 or toll-free 800 558 5253, access code 21711924.

Reject the Inadequate Goldcorp Offer

As previously disclosed, the Osisko Board of Directors has unanimously recommended that Osisko shareholders reject the hostile take-over bid initiated by Goldcorp and not tender their Osisko shares to the Goldcorp offer. The Osisko Board determined that the Goldcorp offer fails to adequately compensate Osisko shareholders for, among others things, the strategic value of Osisko's world-class asset base, the significant upside potential of Osisko's Canadian Malartic Mine, or the increased risk inherent in Goldcorp common shares. The full basis for the Osisko Board's recommendation is available in a Directors' Circular, a copy of which is available online at www.osisko.com.

Shareholders who have questions or who may have already tendered their shares to the Goldcorp Offer and wish to withdraw them, may do so by contacting our Information Agent, Laurel Hill Advisory Group at:

North American Toll Free: 1-877-452-7184

Banks, Brokers or collect calls: 416-304-2011

Email: assistance@laurelhill.com

About Osisko Mining Corporation

Osisko Mining Corporation operates the Canadian Malartic Gold Mine in Malartic, Québec and is pursuing exploration on a number of properties in Ontario and Mexico.

Mr. Luc Lessard, Eng., Senior Vice-President and Chief Operating Officer of Osisko, is the Qualified Person who has reviewed this news release and is responsible for the technical information reported herein, including verification of the data disclosed.

For further information on Canadian Malartic, please see at www.osisko.com or at www.sedar.com "Updated resource and reserve estimates for the Canadian Malartic Project Malartic, Quebec", dated May 10, 2011 and prepared by Belzile Solutions Inc. and G Mining Services Inc., as updated by press releases dated February 19, 2013 and March 12, 2014.

Cautionary Notes Concerning Estimates of Mineral Resources

This news release uses the terms measured, indicated and inferred resources as a relative measure of the level of confidence in the resource estimate. Readers are cautioned that mineral resources are not economic mineral reserves and that the economic viability of resources that are not mineral reserves has not been demonstrated. In addition, inferred resources are considered too geologically speculative to have any economic considerations applied to them. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies or economic studies except for Preliminary Assessment as defined under NI 43-101. Readers are cautioned not to assume that further work on the stated resources will lead to mineral reserves that can be mined economically.

Forward-Looking Statements

Certain statements contained in this press release may be deemed "forward-looking statements". All statements in this release, other than statements of historical fact, that address events or developments that Osisko expects to occur, are forward looking statements. Forward looking statements are statements that are not historical facts and are generally, but not always, identified by the words "expects", "plans", "anticipates", "believes", "intends", "estimates", "projects", "potential", "scheduled" and similar expressions, or that events or conditions "will", "would", "may", "could" or "should" occur including, without limitation, the mining of the Barnat and Jeffrey zones commencing in 2017, the stabilization of mill throughput, the completion of optimization programs, the decrease of costs and increase of grade and gold production, the production of strong free cash flow for a long time, the Corporation's view on the quality and the potential of its Canadian Malartic asset and on Goldcorp common shares, and that mining of the deposits identified in this press release will be executed timely and fully, and will return values identified in the foregoing updated estimate. Although Osisko believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, including, without limitation, that all technical, political and financial conditions will be met in order to continue mining operations at Canadian Malartic to allow for the full extraction of the mining reserves, such statements are not guarantees of future performance and actual results may differ materially from those in forward looking statements.

Factors that could cause the actual results to differ materially from those in forward-looking statements include gold prices, Osisko's limited experience with production and mining operations, uninsured risks, validity of estimates, regulatory framework and changes, defects in title, availability of personnel, materials and equipment, timeliness of government approvals, actual performance of facilities, equipment and processes relative to specifications and expectations, unanticipated environmental impacts on operations market prices, continued availability of capital and financing and general economic, market or business conditions. These factors are discussed in greater detail in Osisko's most recent Annual Information Form and in the most recent Management Discussion and Analysis filed on SEDAR, which also provide additional general assumptions in connection with these statements. Osisko cautions that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on forward-looking statements should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. Osisko believes that the expectations reflected in those forward-looking statements are reasonable, but no assurance can be given that these expectations will prove to be correct and such forward-looking statements included in this press release should not be unduly relied upon. These statements speak only as of the date of this press release.