Osisko Discovers Two New Gold-Copper Zones at Upper Beaver

Osisko Discovers Two New Gold-Copper Zones at Upper Beaver 
High-Grade Results Include 9.3 g/t Au with 1.7% Cu over 18.1 Metres 
MONTREAL, QUEBEC -- (Marketwire) -- 03/21/13 -- Osisko Mining
Corporation (TSX:OSK)(FRANKFURT:EWX) ("Osisko") is pleased to
announce that new drilling at the Upper Beaver gold project located
in Kirkland Lake, Ontario has led to the discovery of two new
gold-copper zones.  
The following intersections highlight high-grade results from the two
new discoveries: 

--  East Basalt Zone Discovery: 9.3 g/t Au with 1.7% Cu over 18.1 metres
    (hole UB13-284) and 2.2 g/t Au with 0.5% Cu over 17.8 metres (hole UB13-
--  North Q Zone Discovery: 11.0 g/t Au with 1.6% Cu over 2.0 metres (hole

Additional new results from infill drilling on previously known
mineralized zones include the following highlights: 3.2 g/t Au with
0.8% Cu over 30.0 metres (UB13-278), 16.1 g/t Au with 8.8% Cu over
3.0 metres and 11.4 g/t Au with 3.3% Cu over 3.0 metres (hole
UB13-280) from the North Basalt Zone and 5.4 g/t Au with 0.5% Cu over
59.0 metres (hole UB13-262W4) from the Porphyry West Zone. 
The table below outlines the results of 10 new holes completed in
2013 as part of the ongoing exploration and in-fill resource
definition drill program at Upper Beaver:  

Hole #          From (m)  To (m) Interval (m)  Cu (%) Au (g/t)          Zone
New zones                                                                   
UB13-279            92.0    93.0          1.0    0.22     0.81   East Basalt
UB13-281           120.0   123.0          3.0    0.18     3.16   East Basalt
UB13-284           147.0   165.1         18.1    1.70     9.30   East Basalt
including          154.0   165.1         11.1    2.75    13.05   East Basalt
UB13-287           170.0   187.8         17.8    0.50     2.20   East Basalt
UB13-282           174.0   177.0          3.0    0.89     2.34       North Q
and                185.0   192.0          7.0   trace     1.28       North Q
and                264.0   272.0          8.0    0.56     3.20       North Q
including          269.0   271.0          2.0    1.57    11.00       North Q
and                311.0   322.0         11.0    0.59     0.91       North Q
UB13-288           177.0   182.0          5.0    0.12     1.46       North Q
and                196.0   199.0          3.0    1.53     2.56       North Q
and                277.0   291.0         14.0    0.30     1.84       North Q
including          280.0   284.0          4.0    0.75     4.40       North Q
Infill holes                                                                
UB13-262W4                                                          Infill -
                   812.0   871.0         59.0    0.53     5.43 Porphyry West
including                                                           Infill -
                   829.0   844.0         15.0    1.03    14.60 Porphyry West
UB13-276           333.0   334.0          1.0    1.32     4.83  North Basalt
and                423.0   427.0          4.0   trace     1.48  North Basalt
UB13-278           360.0   390.0         30.0    0.80     3.20  North Basalt
including          364.0   368.0          4.0    1.70     9.70  North Basalt
and                370.0   380.0         10.0    0.90     2.80  North Basalt
and                385.0   390.0          5.0    1.00     3.80  North Basalt
UB13-280           447.0   450.0          3.0    8.81    16.10  North Basalt
and                479.0   482.0          3.0    3.23    11.40  North Basalt

New Discoveries: East Basalt Zone and the North Q Zone 
Step-out exploration drilling in the first quarter of 2013 has
intersected two new gold-copper discoveries: the East Basalt Zone and
the North Q Zone, both occurring in mafic volcanic rocks adjacent to
the Upper Beaver Igneous Complex.  
Four holes (UB13-279, -281, -284 and -287) drilled approximately 700
metres north-east of the Upper Beaver deposit have intersected new
copper-gold mineralization in the East Basalt Zone. All four holes
drilled on the same section intersected the mineralization starting
at 75 m below surface. The most significant result was intersected in
hole UB13-284 where a 18.1 metre thick continuous zone of gold and
copper mineralization assayed 9.3 g/t Au with 1.7% Cu, included is an
interval assaying 13.1 g/t Au with 2.8% Cu over 11.1 metres. Hole
UB13-287 drilled below UB13-284 intersected 2.2 g/t Au with 0.5% Cu
over 17.8 metres. The chalcopyrite-magnetite stringer mineralization
at the East Basalt Zone dips steeply to the north and resembles the
mineralization previously mined near the south-west margin of the
igneous complex.  
Two holes (UB13-282 and -288) drilled approximately 400 metres
north-west of the Upper Beaver deposit intersected the new North Q
Zone. The holes intersected multiple stringers of gold and copper
mineralization approximately 200 metres below surface with
significant intervals assaying 3.2 g/t Au with 0.6% Cu over 8.0
metres including 11.0 g/t Au with 1.6% Cu over 2.0 metres (hole
UB13-182) and 1.84 g/t Au with 0.3% Cu over 14.0 metres including 4.4
g/t Au with 0.75% Cu over 4.0 metres (UB13-288). 
North Basalt Zone 
The North Basalt Zone is located approximately 800 metres north of
the Upper Beaver deposit and was initially discovered by Queenston in
2005 in drill hole UB05-13 assaying 0.5 g/t Au over 8.0 metres. In
2006 drilling continued to target the zone including hole UB06-51
intersecting two intervals assaying 6.2 g/t Au with 1.3% Cu over 9.9
metres and 8.0 g/t Au with 1.0% Cu over 9.1 metres. Later in 2006
drilling at the North Basalt Zone was postponed as emphasis was
focussed to the south to extend the primary Upper Beaver deposit. 
Three new holes targeted the North Basalt Zone located west of the
north-south trending diabase dyke. Hole UB13-278 intersected a 30.0
metre wide zone of mineralization assaying 3.2 g/t Au with 0.8% Cu
including 9.7 g/t Au with 1.7% Cu over 4.0 metres at approximately
300 m below surface. Fifty metres below this interval hole UB13-280
intersected high grade mineralization assaying 16.1 g/t Au with 8.8%
Cu over 3.0 metres and 11.4 g/t Au with 3.3% Cu over 3.0 metres.  
In-fill Resource Definition 
Drilling continues to confirm the continuity of the mineralization in
the western portion of the main Upper Beaver deposit. At
approximately 700 metres below surface hole UB13-262W4 intersected a
thick zone of mineralization assaying 5.4 g/t Au with 0.5% Cu over
59.0 metres including 8.0 g/t Au with 0.7% Cu over 32.0 m. This
interval is approximately 30 m above previous hole UB12-262W3 that
cut a similar wide interval assaying 5.5 g/t Au with 0.6% Cu over
54.0 metres. (See News Release dated January 30, 2013). 
About Upper Beaver 
The Upper Beaver project is 100% owned by Osisko Mining Ltd., a
wholly-owned subsidiary of Osisko. The Upper Beaver mine produced
approximately 140,000 oz of gold and 12 million pounds of copper
intermittently from 1912 to 1971, from 526,678 tonnes averaging 8.31
g/t Au and 1.03% Cu. Queenston commenced exploration on the property
in 2005 and defined the first new mineral resource in 2009. Since
2005 three-hundred and eighty new diamond drill holes (including
wedges) have been completed on the property, representing 236,874
metres of drilling.  
A Preliminary Economic Assessment ("PEA") was completed on Upper
Beaver in early 2012 (Queenston press release, February 16, 2012).
The PEA studied the economics of building a 2,000 tonne per day
mine/mill complex at Upper Beaver that would produce on average
120,000 oz of gold and 5.3 million pounds of copper annually with
first production targeted in 2016. The permit to sink a new 1,300 m
deep shaft was received in September 2012 and detailed engineering,
procurement and shaft collar excavation have commenced. The PEA
incorporated the May 2011 mineral resource for Upper Beaver,
containing 3,074,000 t averaging 7.0 g/t Au (690,000 oz) with 0.5% Cu
(36.6 M lbs) (Indicated) and 3,093,000 t averaging 6.2 g/t Au
(616,000 oz) with 0.4% Cu (28.0 M lbs) (Inferred) (Queenston press
release, May 4, 2011).  
An updated mineral resource was announced on September 2012,
increasing the indicated resource by 112% to 6,870,000 t averaging
6.6 g/t Au (1,461,000 oz) and 0.37% Cu (56 M lbs), and increasing the
inferred resource by 16% to 4,570,000 t averaging 4.9 g/t Au (712,000
oz) and 0.32% Cu (32 M lbs) (Queenston press release, September 26,
The focus at Upper Beaver for 2013-2014 will be on the development of
the 1,300 metre exploration shaft, including engineering, design and
fabrication of the head frame and hoisting facilities budgeted at $70
million. The shaft collar has now been established to a depth of 26
metres and exploration on the deposit continues with six drills. In
addition to the development program at Upper Beaver the Company has
budgeted an additional $20 million for 2013 exploration in the
Kirkland Lake gold camp.  
Quality Control 
True widths of reported intervals are interpreted based on drill-hole
intercepts and interpreted orientations of intersected lithologies
and are estimated at 65-80% of the core length interval. Assays are
uncut. Intercepts occur within geological confines of major zones but
have not been correlated to individual vein domains at this time. All
NQ core assays reported were obtained by standard 30 g
fire-assaying-AA finish or gravimetric finish at Swastika
Laboratories of Swastika, Ontario. Drill program design, Quality
Assurance/Quality Control and interpretation of results is performed
by qualified persons employing a QA/QC program consistent with NI
43-101 and industry best practices. The Upper Beaver project is
supervised by Mark Masson, P.Geo. Standards and blanks are submitted
every 25 samples for QA/QC purposes by the Company as well as the
lab. Approximately 5% of sample rejects and/or pulps are sent to
secondary laboratories for check assaying.  
Mr. William McGuinty, P.Geo. is Project Manager for Osisko Mining
Ltd. and is the Qualified Person responsible for the technical
information reported herein, including verification of the data
About Osisko 
Osisko Mining Corporation operates the Canadian Malartic Gold Mine in
Malartic, Quebec and is carrying out aggressive exploration and
project development elsewhere in Canada and Latin America.  
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 that further work 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
continued development of the Upper Beaver project and more
specifically the development of the exploration shaft. Although
Osisko believes the expectations expressed in such forward-looking
statements are based on reasonable assumptions, including, without
limitation, that all technical, economical and financial conditions
will be met in order to achieve such events qualified by the
foregoing cautionary note regarding forward looking statements, 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, access to skilled consultants, mining development and
construction personnel, results of exploration and development
activities, Osisko's limited experience with production and mining
operations, uninsured risks, 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.
John Burzynski
Vice-President Corporate Development
(416) 363-8653 
Sylvie Prud'homme
Director of Investor Relations
(514) 735-7131
Toll Free: 1-888-674-7563
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