DML.TO · 2017-04-20 12:00:00

Denison Announces 22.1 Metres of High-Grade Mineralization from Gryphon D Series as Winter Drilling Wraps up at Wheeler River

Drill Results

Denison Mines Corp.

1100 – 40 University Ave

Toronto, ON M5J 1T1

www.denisonmines.com

@DenisonMinesCo

PRESS RELEASE

DENISON ANNOUNCES 22.1 METRES OF HIGH-GRADE MINERALIZATION

FROM GRYPHON D SERIES AS WINTER DRILLING

WRAPS UP AT WHEELER RIVER

Toronto, ON – April 20, 2017 Denison Mines Corp. (“Denison” or the “Company”) (DML: TSX, DNN: NYSE

MKT) is pleased to report additional high-grade int ersections from the Gryphon D series lenses of

mineralization, which remain outside of the resourc es estimated for the Gryphon deposit in late 2015. The

Gryphon deposit accompanies the Phoenix deposit on the Company’s 60% owned Wheeler River project,

which is the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of the

Athabasca Basin. In addition, the Company is please d to report radiometric equivalent grade results

(“eU 3O8“) from the final drill holes completed during the winter 2017 drill program at Wheeler River.

Drill hole WR-633D3 intersected high-grade mineralization over a cumulative interval of 22.1 metres

within the position of the D series lenses. The result was highlighted by two mineralized intervals, as

follows:

• 18.7 metres at 1.9% eU 3O8 (including 13.2 metres at 2.5% eU 3O8), and

• 3.4 metres at 3.1% eU 3O8

The mineralized intervals occur approximately 26 metres down-dip of the 11.0 metre interval grading 5.3%

U3O8 previously reported in drill hole WR-641 (see Denis on’s Press Release dated May 26, 2016). The

mineralized intervals in WR-633D3 are also located approximately 43 metres down-dip of the 1.2 metre

interval grading 7.50% eU 3O8 and 1.7 metre interval grading 2.90% eU 3O8 in drill hole WR-689 (see

Denison’s Press Release dated March 29, 2017).

Infill drilling within the Gryphon deposit’s A, B and C series lenses has continued as part of the winter 2017

program, with a further 4 drill holes having been completed prior to the completion of winter drilling activities.

The radiometric equivalent grade results continue t o confirm continuity and high-grades of the Gryphon

deposit lenses. Highlight intersections for the further 4 infill holes completed include:

• 3.9% eU 3O8 over 7.1 metres (including 6.1% eU 3O8 over 4.4 metres), and

• 3.8% eU 3O8 over 4.0 metres (including 4.4% eU 3O8 over 3.4 metres) in drill hole WR-567D1

• 5.9% eU 3O8 over 6.2 metres (including 8.7% eU 3O8 over 4.1 metres), and

• 2.1% eU 3O8 over 3.6 metres (including 2.6% eU 3O8 over 2.8 metres) in drill hole WR-567D2

• 2.7% eU 3O8 over 5.3 metres (including 9.4% eU 3O8 over 1.3 metres) in drill hole WR-688D3

• 2.0% eU 3O8 over 4.6 metres (including 4.1% eU 3O8 over 1.9 metres) in drill hole WR-606D2

Denison's President & CEO, David Cates, commented “We are pleased to have completed another safe

and successful drill season at Wheeler River this w inter. Our Saskatoon based exploration team has

delivered another productive season of drilling, wi th results in the vicinity of the Gryphon deposit

demonstrating the potential for meaningful addition al resources – particularly with some notable

intersections in the D series lenses, which are sit uated outside of the existing resources estimated f or the

deposit. As we work towards increasing the confiden ce for the existing resources at the Gryphon deposi t,

from inferred to indicated, the infill drill program has produced a solid set of results confirming th icknesses

and high-grades. The team is eagerly awaiting chemi cal assay results over the coming weeks, and is

looking forward to commencing the summer drill program towards the end of May”.

Exploration Drilling Outside of the Gryphon Resource

A further two exploration drill holes, WR-633D3 and WR-690, were completed to test the continuity of t he

D series lenses between previous exploration holes completed on an approximate 50 x 50 metre spacing.

Drill hole WR-633D3 tested for D series mineralization approximately 26 metres down-dip to the southeast

of drill hole WR-641, and returned high-grade mineralization over a cumulative interval of 22.1 metres within

the position of the D series lenses.

Drill hole WR-690 tested for D series mineralization approximately 26 metres down plunge to the northeast

of drill hole WR-641. The drill hole intersected moderate mineralization in positions of the B, C and D series

lenses.

The D series lenses are not included in the current resource estimate for the Gryphon deposit and occu r

footwall, and within 200 metres to the north and no rthwest, of the A, B and C series lenses. Mineraliz ation

amongst the D series lenses remains open along stri ke to the northeast and southwest. Radiometric

equivalent grade results for drill holes WR-633D3 a nd WR-690 are provided in Table 1 and locations

illustrated in Figures 1 to 5.

Table 1: Mineralized intersections from drill holes WR-633D3 and WR-690 completed during winter 2017

Section Drill Hole From (m) To (m) Length (m) (5) eU3O8

(%) (1)(2)(4)

Lens

Designation

5200GP

WR-633D3 674.6 675.6 1.0 0.12 B Series

and 742.8 743.8 1.0 0.11 D Series

and (3) 753.2 771.9 18.7 1.9 D Series

including 753.3 756.4 3.1 0.75 D Series

including 758.6 771.8 13.2 2.5 D Series

and 774.3 777.7 3.4 3.1 D Series

5225GP

WR-690 585.9 587.0 1.1 0.18 B Series

and 593.0 594.0 1.0 0.74 B Series

and 654.5 655.5 1.0 0.70 C Series

and 722.3 723.3 1.0 0.23 D Series

and 726.1 727.1 1.0 0.18 D Series

Notes:

1. eU 3O8 is radiometric equivalent U 3O8 from a calibrated total gamma downhole probe. eU 3O8 results are preliminary in nature

and all mineralized intervals will be sampled and submitted for chemical U 3O8 assay.

2. Intersection interval is composited above a cut- off grade of 0.1% eU 3O8 unless otherwise indicated.

3. Intersection interval is composited above a cut- off grade of 0.05% eU 3O8.

4. Composites are compiled using 1.0 metre minimum ore thickness and 2.0 metres maximum waste.

5. As the drill holes are oriented steeply toward t he northwest and the basement mineralization is interpreted to dip moderately

to the southeast, the true thickness of the mineralization is expected to be approximately 75% of the intersection lengths.

Infill and Delineation Drilling of the Gryphon Resource

The infill and delineation drilling program is desi gned to upgrade the current inferred resources of t he

Gryphon deposit to an indicated level of confidence by increasing the previous 50 x 50 metre drill spa cing

to an approximate 25 x 25 metre spacing. The progr am commenced in 2016, with the completion of an

initial five drill holes. A further 17 drill holes, totaling approximately 8,402 metres, have been completed as

part of the winter 2017 program, with a further 18 drill holes planned to be completed during the summ er

2017 program.

Radiometric equivalent grade results for the latest four infill drill holes completed as part of the winter 2017

program are provided in Table 2, and locations show n in Figures 1 to 4. The results are largely consis tent

with the inferred grade model and confirm continuit y and high-grades of the Gryphon deposit A, B and C

mineralized lenses.

Table 2: Mineralized intersections from infill drill holes WR-567D1, WR-567D2, WR-688D3 and WR-606D2

completed during winter 2017

Section Drill Hole From (m) To (m) Length (m) (5) eU3O8

(%) (1)(2)(4)

Lens

Designation

4975GP

WR-567D1 674.3 675.9 1.6 0.33 A Series

and 689.8 690.8 1.0 0.66 A Series

and 694.9 696.9 2.0 1.3 A Series

including (3) 695.0 696.0 1.0 2.4 A Series

and 700.0 707.1 7.1 3.9 A Series

including (3) 701.1 705.5 4.4 6.1 A Series

and 723.1 727.1 4.0 3.8 B Series

including (3) 723.4 726.8 3.4 4.4 B Series

WR-567D2 664.5 665.6 1.1 0.42 A Series

and 670.1 671.1 1.0 0.89 A Series

and 691.2 692.2 1.0 1.2 A Series

and 694.3 695.7 1.4 0.71 A Series

and 698.4 704.6 6.2 5.9 A Series

including (3) 700.2 704.3 4.1 8.7 A Series

and 713.5 714.9 1.4 0.22 B Series

and 732.8 736.4 3.6 2.1 B Series

including (3) 733.0 735.8 2.8 2.6 B Series

and 739.0 740.0 1.0 0.40 B Series

and 744.75 747.35 2.6 0.28 B Series

5100GP

WR-688D3 758.1 759.1 1.0 0.24 A Series

and 762.4 767.7 5.3 2.7 A Series

including (3) 764.4 765.7 1.3 9.4 A Series

including (3) 766.5 767.5 1.0 1.3 A Series

and 775.2 776.2 1.0 0.12 B Series

and 779.1 780.1 1.0 0.11 B Series

and 780.4 781.4 1.0 0.10 B Series

and 782.2 785.1 2.9 0.71 B Series

including (3) 783.5 784.5 1.0 1.57 B Series

and 793.1 794.2 1.1 5.4 C Series

including (3) 793.2 794.2 1.0 5.9 C Series

WR-606D2 764.3 765.3 1.0 0.11 A Series

and 785.4 786.4 1.0 0.15 A Series

and 792.4 793.4 1.0 0.11 A Series

and 794.2 798.8 4.6 2.0 A Series

including (3) 795.9 797.8 1.9 4.1 A Series

and 803.5 808.1 4.6 0.5 B Series

including (3) 804.6 805.6 1.0 1.5 B Series

Notes:

1. eU 3O8 is radiometric equivalent U 3O8 from a calibrated total gamma downhole probe. eU 3O8 results are preliminary in nature

and all mineralized intervals will be sampled and submitted for chemical U 3O8 assay.

2. Intersection interval is composited above a cut- off grade of 0.1% eU 3O8 unless otherwise indicated.

3. Intersection interval is composited above a cut- off grade of 1% eU 3O8.

4. Composites are compiled using 1.0 metre minimum ore thickness and 2.0 metres maximum waste.

5. As the drill holes are oriented steeply toward t he northwest and the basement mineralization is interpreted to dip moderately

to the southeast, the true thickness of the mineralization is expected to be approximately 75% of the intersection lengths.

Illustrative Figures & Further Details

A plan map of the northeast plunging Gryphon mineralized lenses, projected up to the simplified basement

geology at the sub-Athabasca unconformity, is provi ded in Figure 1. The plan map shows the location of

the A, B, C and D series lenses interpreted to the end of 2016 with the winter 2017 mineralized pierce points

shown as orange or yellow stars. The inset on Figure 1 shows a schematic cross section of the A, B, C and

D series lenses and their respective inclined longitudinal section windows (as shaded rectangles). Fig ures

2 to 5 provide inclined longitudinal sections of the Gryphon A, B, C and D series lenses respectively. Shown

on the inclined longitudinal sections are the various mineralized lenses projected to their respective planes

and drill hole pierce points. Drill hole pierce po ints prior to the winter 2017 program are shown as black

circles whereas winter 2017 pierce points are shown as either orange stars (mineralized – previously

reported intersection), yellow stars (mineralized – new intersection) or grey circles (not significant ly

mineralized).

It should be noted for Figures 1 to 5 that mineralized lenses are designated either A, B, C or D series, and

coloured accordingly, based on the interpreted stra tigraphic planes in which they occur (i.e. their po sition

relative to the different geological units and faul t structures identified). In Press Releases from 20 16, all

new lenses defined outside of the Gryphon deposit’s A, B and C series lenses, which constitutes the current

inferred resource estimate, were designated D series lenses. Further geological data from 2017 drilling and

an improved geological model has allowed Denison to re-classify some of the previously modelled D series

mineralized lenses into new A, B or C series lenses based on their stratigraphic position ahead of fut ure

resource estimation. The modelled mineralized lense s shown in Figures 1 to 5 are defined using a 0.05%

U3O8 or eU 3O8 grade shell and minimum thickness of two metres. T here is no certainty that the modelled

mineralized lenses shown will constitute future mineral resources and they may be subject to modifications

as further drilling data becomes available.

Further details regarding the Gryphon deposit and t he current mineral resource estimates are provided in

the NI 43-101 Technical Report for the Wheeler Rive r project titled “Preliminary Economic Assessment for

the Wheeler River Uranium Project, Saskatchewan, Ca nada" dated April 8, 2016 with an effective date of

March 31, 2016. A copy of this report is availabl e on Denison’s website and under its profile on SEDAR

at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

Qualified Persons

Dale Verran, MSc, Pr.Sci.Nat., Denison's Vice Presi dent, Exploration, who is a Qualified Person in

accordance with the requirements of NI 43-101 has r eviewed and approved the technical information

contained in this release. For a description of the assay procedures and the quality assurance program and

quality control measures applied by Denison, please see Denison's Annual Information Form dated March

24, 2016 filed under the Company's profile on SEDAR (www.sedar.com).

About Wheeler River

Wheeler River is the largest undeveloped high-grade uranium project in the infrastructure rich eastern

portion of the Athabasca Basin region, in northern Saskatchewan. The project is a joint venture betwe en

Denison (60% and operator), Cameco Corp. (“Cameco”) (30%), and JCU (Canada) Exploration Company

Limited (“JCU”) (10%), and is host to the high-grade Gryphon and Phoenix uranium deposits discovered by

Denison in 2014 and 2008, respectively. The Gryphon deposit is hosted in basement rock and is currentl y

estimated to contain inferred resources of 43.0 mil lion pounds U 3O8 (above a cut-off grade of 0.2% U 3O8)

based on 834,000 tonnes of mineralization at an ave rage grade of 2.3% U 3O8. The Phoenix unconformity

deposit is located approximately 3 kilometres to th e southeast of Gryphon and is estimated to include

indicated resources of 70.2 million pounds U 3O8 (above a cut-off grade of 0.8% U 3O8) based on 166,000

tonnes of mineralization at an average grade of 19.1% U 3O8, and is the highest grade undeveloped known

uranium deposit in the world.

On April 4th, 2016, Denison announced the results of a Preliminary Economic Assessment (“PEA”) for the

Wheeler River Project, which considers the potentia l economic merit of co-developing the high-grade

Gryphon and Phoenix deposits as a single undergroun d mining operation. The PEA returned a base case

pre-tax Internal Rate of Return ("IRR") of 20.4% ba sed on the current long term contract price of uran ium

(US$44.00 per pound U 3O8), and Denison's share of estimated initial capital expenditures ("CAPEX") of

CAD$336M (CAD$560M on 100% ownership basis). Exploration results from the winter and summer 2016

drilling program have not been incorporated into the resource estimate or the PEA. The PEA is preliminary

in nature and includes inferred mineral resources t hat are considered too speculative geologically to have

the economic considerations applied to them to be c ategorized as mineral reserves, and there is no

certainty that the preliminary economic assessment will be realized. Mineral resources are not mineral

reserves and do not have demonstrated economic viab ility. On July 19th, 2016 Denison announced the

initiation of a Pre-Feasibility Study ("PFS") for t he Wheeler River property and the complimentary

commencement of an infill drilling program at the G ryphon deposit to bring the inferred resources to a n

indicated level of confidence.

As previously announced on January 10, 2017, Deniso n has entered into an agreement with its Wheeler

River Joint Venture partners, Cameco and JCU, to fu nd 75% of Joint Venture expenses in 2017 and 2018

(ordinarily 60%) in exchange for an increase in Denison's interest in the project to up to approximately 66%.

Under the terms of the agreement, Cameco will fund 50% of its ordinary 30% share in 2017 and 2018, and

JCU is expected to continue to fund its 10% interest in the project.

About Denison

Denison is a uranium exploration and development company with interests focused in the Athabasca Basin

region of northern Saskatchewan. Including its 60% owned Wheeler River project, which hosts the high-

grade Phoenix and Gryphon uranium deposits, Denison 's exploration portfolio consists of numerous

projects covering over 330,000 hectares in the infr astructure rich eastern Athabasca Basin. Denison's

interests in Saskatchewan also include a 22.5% ownership interest in the McClean Lake joint venture, which

includes several uranium deposits and the McClean L ake uranium mill, which is currently processing ore

from the Cigar Lake mine under a toll milling agreement, plus a 25.17% interest in the Midwest deposit and

a 63.01% interest in the J Zone deposit on the Wate rbury Lake property. Both the Midwest and J Zone

deposits are located within 20 kilometres of the McClean Lake mill.

Denison is also engaged in mine decommissioning and environmental services through its Denison

Environmental Services division and is the manager of Uranium Participation Corp., a publicly traded

company which invests in uranium oxide and uranium hexafluoride.

For more information, please contact

David Cates (416) 979-1991 ext. 362

President and Chief Executive Officer

Sophia Shane (604) 689-7842

Investor Relations

Follow Denison on Twitter @DenisonMinesCo

Cautionary Statement Regarding Forward-Looking Statements

Certain information contained in this press release constitutes “forward-looking information”, within the meaning of the United States

Private Securities Litigation Reform Act of 1995 an d similar Canadian legislation concerning the busin ess, operations and financial

performance and condition of Denison. Generally, th ese forward-looking statements can be identified by the use of forward-looking

terminology such as “plans”, “expects”, “budget”, “scheduled”, “estimates”, “forecasts”, “intends”, “anticipates” or “believes”, or the

negatives and/or variations of such words and phrases, or state that certain actions, events or results “may”, “could”, “would”, “might”

or “will be taken”, “occur”, “be achieved” or “has the potential to”. In particular, this press release contains forward-looking information

pertaining to the following: exploration (including drilling) and evaluation act ivities, plans and objectives; potential mineraliza tion of

drill targets; the estimates of Denison's mineral resources and the results of its PEA.

Forward looking statements are based on the opinions and estimates of management as of the date such statements are made, and

they are subject to known and unknown risks, uncert ainties and other factors that may cause the actual results, level of activity,

performance or achievements of Denison to be materi ally different from those expressed or implied by s uch forward-looking

statements. Denison believes that the expectations reflected in this forward-looking information are r easonable but there can be no

assurance that such statements will prove to be acc urate and may differ materially from those anticipa ted in this forward looking

information. For a discussion in respect of risks and other factors that could influence forward-looking events, please refer to the “Risk

Factors” in Denison’s Annual Information Form dated March 24, 2016 available under its profile at www.sedar.com and in its Form

40-F available at www.sec.gov/edgar.shtml . These factors are not, and should not be construed as being, exhaustive.

Accordingly, readers should not place undue relianc e on forward-looking statements. The forward-lookin g information contained in

this press release is expressly qualified by this cautionary statement. Denison does not undertake any obligation to publicly update or

revise any forward-looking information after the date of this press release to conform such information to actual results or to changes

in its expectations except as otherwise required by applicable legislation.

Cautionary Note to United States Investors Concerning Estimates of Measured, Indicated and Inferred Mineral Resources: This

press release may use the terms “measured”, “indicated” and “inferred” mineral resources. United States investors are advised that while

such terms are recognized and required by Canadian regulations, the United States Securities and Exchange Commission does not

recognize them. “Inferred mineral resources” have a great amount of uncertainty as to their existence, and as to their economic and legal

feasibility. 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 other economic studies. United States

investors are cautioned not to assume that all or any part of measured or indicated mineral resources will ever be converted into mineral

reserves. United States investors are also cautioned not to assume that all or any part of an inferred mineral resource exists, or is

economically or legally mineable.

Figure 1: Plan map of the northeast plunging Gryphon mineralized lenses projected up to the simplified basement geology at the

sub-Athabasca unconformity.

Figure 2: Inclined longitudinal section of the Gryphon A series lenses.

← Back to feed