Denison Reports High-Grade Uranium Intercepts Northeast of the Gryphon Deposit
Denison Mines Corp.
1100 – 40 University Ave
Toronto, ON M5J 1T1
www.denisonmines.com
@DenisonMinesCo
PRESS RELEASE
DENISON REPORTS HIGH-GRADE URANIUM INTERCEPTS
NORTHEAST OF THE GRYPHON DEPOSIT
Toronto, ON – April 18, 2018 Denison Mines Corp. (“Denison” or the “Company”) (TSX: DML) (NYSE
MKT: DNN) (NYSE American: DNN) is pleased to report the discovery of high-grade uranium mineralization
600 metres and 1 kilometre to the northeast of the Gryphon uranium deposit, on the Company’s 63.3%
owned Wheeler River project, in northern Saskatchew an. The winter drilling program is now complete,
resulting in a total of 21,153 metres drilled in 29 diamond drill holes. The program was focused on s tep-
out drilling along strike of the Gryphon deposit an d reconnaissance level regional exploration along t he K-
North and K-West trend. The winter 2018 drilling results reported in this release are preliminary, equivalent
uranium (“eU 3O8”) results derived from a calibrated downhole probe. Drill core samples have been collected
and submitted for chemical assay, results of which will be reported when available.
Regional Exploration Highlights:
High-grade intercepts were obtained at the sub-Atha basca unconformity along the K-North trend , to the
northeast of Gryphon, from reconnaissance drill fences spaced 200 metres apart, including:
• 0.55% eU 3O8 over 5.6 metres, located 600 metres northeast of G ryphon, including 2.3% eU 3O8
over 1.0 metre in drill hole WR-704; and
• 0.94% eU 3O8 over 3.5 metres, located 1 kilometre northeast of Gryphon, including 2.7% eU 3O8
over 1.0 metre in drill hole WR-710D1.
The results indicate a continuation of the Gryphon mineralizing system to the northeast, and highlight the
potential for the discovery of an additional high-g rade uranium deposit within the basement or at the
unconformity along strike of Gryphon.
In addition, wide-spaced reconnaissance drilling al ong the K-West trend , approximately 500 metres west
and northwest of the Gryphon deposit, has identifie d the hallmarks of a significant fertile trend with the
potential to host high-grade uranium – including a large re-activated graphite-bearing fault zone,
hydrothermal alteration and elevated radioactivity.
Gryphon Exploration Highlights:
Multiple basement intercepts were obtained from ste p-out drilling on 50 to 100 metre centres immediate ly
along strike to the northeast of the Gryphon deposit. Highlights from the Gryphon step-out drilling include:
• Intercepts of upper basement mineralization extend ing the E series lenses to the northeast:
o 2.5% eU 3O8 over 1.3 metres in drill hole WR-696;
o 0.86% eU 3O8 over 1.9 metres in drill hole WR-709; and
o 0.38% eU 3O8 over 2.8 metres in drill hole WR-702.
• Intercept of mineralization, 100 metres along stri ke to the northeast of the previous down-plunge
extent of A series mineralization for the Gryphon deposit, including:
o 0.82% eU 3O8 over 3.9 metres, including 2.1% eU 3O8 over 1.0 metre in drill hole WR-698
Further details of the winter 2018 drilling program and the results are provided below, including
comprehensive drilling tables of preliminary eU 3O8 results.
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Dale Verran, Vice President Exploration of Denison commented, “The last time Denison undertook any
significant regional exploration on Wheeler was in 2014, which resulted in the discovery of Gryphon.
The initiation of regional exploration once again i n 2018 has been met with positive results
delivering high-grade intercepts along the K-North trend and identifying K-West as a significant
fertile trend. Furthermore, the initial step-outs f rom Gryphon confirm potential to continue to
expand the mineral resource. We look forward to the summer drilling program to continue to test
regional targets across the Wheeler River property and commence follow-up activities where
warranted.”
Details of Regional Exploration Results:
K North
A total of eight reconnaissance holes were complete d along the K-North trend to the northeast of the
Gryphon deposit. Drilling was completed along four drill fences located approximately 200 metres apart
with two drill holes per fence. On each fence, the drill holes were designed to test the G-Fault (prin ciple
mineralized structure at Gryphon); (1) at the sub-A thabasca unconformity, and (2) within the basement,
approximately 100 metres below the unconformity, re spectively. Preliminary eU 3O8 drilling results are
provided in Table 1 and drill hole locations are shown in Figure 2.
• Three of the four holes designed to test the uncon formity intersected mineralization, including drill
hole WR-704 (2.3% eU 3O8 over 1.0 metre, 600 metres northeast of Gryphon) and WR-710D1 (2.7%
eU 3O8 over 1.0 metre, 1 kilometre northeast of Gryphon).
• Drill hole WR-708, located between WR-704 and WR-7 10D1, did not intersect mineralization but
was interpreted to have overshot the optimal target , intersecting elevated radioactivity at the
unconformity and significant structure and alteration above the unconformity.
• The mineralization intersected in WR-704 and WR-71 0D1 was located at or immediately below the
unconformity and comprised of massive to semi-massi ve uraninite with associated hematite and
clay alteration – typical of unconformity-hosted deposits.
• The drill results indicate the unconformity-relate d mineralizing system extends over approximately
600 metres of strike length (from WR-697D1 to WR-71 0D1) and may have connectivity to the E
series lens mineralization at Gryphon.
• The four drill holes testing the basement confirme d Gryphon-type stratigraphy (graphitic pelitic
gneiss overlying quartz-pegmatite) and encountered Gryphon-like structural disruption along the
G-Fault with associated clay alteration. Basement mineralization was intersected in drill holes WR-
697D1 (0.23% eU 3O8 over 1.0 metre) and WR-700 (0.11% eU 3O8 over 1.0 metre).
K West
The K-West trend is parallel to, and located approximately 500 metres west of, the K-North trend and shares
many geological similarities. During summer 2016, w eak basement-hosted mineralization and extensive
clay alteration was intersected in drill hole WR-66 3 at K-West (see Denison’s press release dated August
4, 2016). Follow-up drilling commenced along strik e of WR-663 as part of the winter 2018 program, wit h
100 metre step-out holes in both directions, and tw o reconnaissance drill holes completed further alon g
strike to the northeast (located at 400 and 750 met res from WR-663, respectively). Preliminary eU 3O8
drilling results are provided in Table 1 and drill hole locations are shown in Figure 2.
• A significant basement fault zone with associated clay alteration was intersected in every hole, with
elevated radioactivity recorded in drill hole WR-71 5 (up to 700 counts per second over 6 metres
using a down-hole 2GHF-1000 triple gamma probe) and drill hole WR-714 (up to 550 counts per
second over 1 metre).
• Taken together, the results indicate K-West is a l arge fertile trend with the potential to host high-
grade uranium within the basement and at the unconformity.
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Table 1: Preliminary Regional Exploration winter 2018 drilling results.
Drill Hole From (m) To (m) Length (m) 5 eU 3O8 (%) 1,2,4 Zone & Location
WR-697D1 557.3 558.3 1.0 0.09
K-North - 400 m
NE of Gryphon and 664.8 665.8 1.0 0.23
WR-700 611.7 612.7 1.0 0.11
WR-701 No significant mineralization.
K-North - 600 m
NE of Gryphon WR-704 561.9 567.5 5.6 0.55
including 3 565.2 566.2 1.0 2.3
WR-705 No significant mineralization. K-North - 800 m
NE of Gryphon WR-708 Elevated radioactivity. Significant alterati on.
WR-710 No significant mineralization.
K-North - 1 km
NE of Gryphon WR-710D1 567.1 570.6 3.5 0.94
including 3 569.4 570.4 1.0 2.7
WR-714 No significant mineralization. Elevated radi oactivity.
K West - see
Figure 2
WR-716 No significant mineralization.
WR-715 No significant mineralization. Elevated radi oactivity.
WR-717 No significant mineralization.
Notes:
1. eU 3O8 is radiometric equivalent U 3O8 derived from a calibrated total gamma down-hole probe.
2. Composited above a cut-off grade of 0.05% eU 3O8 unless otherwise indicated.
3. Composited above a cut-off grade of 1.0% eU 3O8.
4. Composites compiled using 1.0 metre minimum mineralization thickness and 2.0 metres maximum waste.
5. As the drill holes are oriented steeply toward the northwest and the unconformity mineralization is interpreted to be flat-lying, the
true thickness of the mineralization is expected to be approximately 75% of the intersection lengths.
Details of Gryphon Exploration Results:
Gryphon Down-Plunge
The Gryphon deposit remains open in the down-plunge area to the northeast and five holes were completed
in this direction during the winter 2018 drill program. Preliminary eU 3O8 drilling results are provided in Table
2 and drill hole locations are shown in Figure 2.
• Drill hole WR-698, located approximately 100 metre s along strike and to the northeast of the
Gryphon deposit’s A series lenses, intersected 0.82% eU 3O8 over 3.9 metres, including 2.1% eU 3O8
over 1.0 metre.
• Additional weak mineralization was intersected in three follow-up holes drilled on an approximate
50 metre spacing (WR-698D1, WR-703 and WR-707), whi ch showed apparent continuity of the
mineralization and extensive Gryphon-style alteration.
E Series Lenses
A total of seven drill holes were completed to test for Gryphon E series lens mineralization along str ike to
the northeast of the Gryphon deposit. Drill holes w ere spaced approximately 50 metres apart on section s
up to 200 metres away from the Gryphon deposit. Pre liminary eU 3O8 drilling results are provided in Table
2 and drill hole locations are shown in Figure 2
• Six of the seven drill holes were mineralized, inc luding WR-696 (2.5% eU 3O8 over 1.3 metres), WR-
709 (0.86% eU 3O8 over 1.9 metres), and WR-702 (0.38% eU 3O8 over 2.8 metres).
• The winter 2018 drilling has extended the E series lens mineralization a further 200 metres to the
northeast. As a result, the E series lenses remain open to the northeast and southwest, and now
have a total strike length of over 500 metres.
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D Series Lenses
Four step-out drill holes were completed on a 50 metre spacing to test for D series lens mineralization along
strike to the southwest of the D series lenses incl uded in the current Gryphon mineral resource estima te.
Preliminary eU 3O8 drilling results are provided in Table 2 and drill hole locations are shown in Figure 2.
• Two of the drill holes were mineralized above the 0.05% eU 3O8 cut-off, with drill hole WR-711
returning a highlight intersection of 0.46% eU 3O8 over 1.1 metres.
Table 2: Preliminary Gryphon Exploration winter 2018 drilling results.
Section Drill Hole From (m) To (m) Length (m) 5 eU 3O8 (%) 1,2,4 Lens Target &
Designation
5350GP
WR-698 775.9 779.8 3.9 0.82
A/B/C Lens
including 3 776.7 777.7 1.0 2.1
and 780.5 781.5 1.0 0.05
WR-698D1 783.2 784.2 1.0 0.06
5400GP
WR-703 806.3 808.6 2.3 0.35
and 813.9 814.9 1.0 0.08
WR-703D1 No significant mineralization.
5450GP WR-707 802.6 803.6 1.0 0.15
5325GP
WR-696 580.8 582.0 1.2 0.28
E Lens
and 595.6 596.9 1.3 2.5
including 3 595.7 596.7 1.0 3.3
and 618.1 619.1 1.0 0.06
and 624.9 625.9 1.0 0.09
and 665.3 666.5 1.2 0.42
5350GP WR-699D1 604.7 605.7 1.0 0.06
and 620.1 621.1 1.0 0.07
5400GP
WR-702 542.6 545.4 2.8 0.38
and 703.7 704.7 1.0 0.09
and 713.6 714.6 1.0 0.44
WR-702D1 556.7 557.7 1.0 0.26
5450GP WR-706 No significant mineralization.
5500GP
WR-709 580.1 582.0 1.9 0.86
including 3 580.1 581.1 1.0 1.0
WR-709D1 Not probed due to drilling issues.
WR-712 580.7 581.7 1.0 0.09
5075GP
WR-711 631.9 632.9 1.0 0.06
D Lens
and 634.2 635.2 1.0 0.06
and 636.0 637.1 1.1 0.46
5000GP WR-713 668.7 670.7 2.0 0.16
5025GP WR-713D1 No significant mineralization.
4975GP WR-718 No significant mineralization.
Notes:
1. eU 3O8 is radiometric equivalent U 3O8 derived from a calibrated total gamma down-hole probe.
2. Composited above a cut-off grade of 0.05% eU 3O8 unless otherwise indicated.
3. Composited above a cut-off grade of 1.0% eU 3O8.
4. Composites compiled using 1.0 metre minimum mineralization thickness and 2.0 metres maximum waste.
5. As the drill holes are oriented steeply toward the northwest and the unconformity 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.
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Illustrative Figures and Further Details
A location map of Wheeler River and the Phoenix and Gryphon deposits is provided in Figure 1. The winter
2018 drill hole locations are provided in Figure 2. Drill traces, mineralized pierce points and Grypho n
mineralized wireframes are projected to the interpr eted basement geology at the sub-Athabasca
unconformity. The interpreted basement geology map has not yet been updated to include the geology
intersected in the winter 2018 program; however, th e revised G-Fault location is shown to illustrate t he
optimal ‘target horizon’ at the unconformity.
Further details regarding the Wheeler River project are provided in the NI 43-101 Technical Report for the
Wheeler River project titled “Technical Report with an Updated Resource Estimate for the Wheeler River
Property, Northern Saskatchewan, Canada" dated March 15, 2018 with an effective date of March 9, 2018.
A copy of this report is available on Denison’s website and under its profile on SEDAR at www.sedar.co m
and on EDGAR at www.sec.gov/edgar.shtml.
Qualified Persons and Data Quality
Dale Verran, MSc, P.Geo, Pr.Sci.Nat., Denison's Vice President, 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.
The Company currently reports preliminary radiometr ic equivalent grades ("eU 3O8"), derived from a
calibrated down-hole total gamma probe, during or u pon completion of its exploration programs and
subsequently reports definitive U 3O8 assay grades following sampling and chemical analys is of the
mineralized drill core. Radiometric equivalent prob e results are subject to data verification procedur es by
qualified persons employed by Denison prior to disc losure. For further details on the total gamma down -
hole probe methods employed by Denison, QAQC procedures and data verification procedures please see
Denison's Annual Information Form dated March 27, 2 018 available on the Company’s website and 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 – including combined Indicated Mineral
Resources of 132.1 million pounds U3O8 at an average grade of 3.3% U3O8, plus combined Inferred Mineral
Resources of 3.0 million pounds U 3O8 at an average grade of 1.7% U 3O8. The project is host to the high-
grade Gryphon and Phoenix uranium deposits (discove red by Denison in 2014 and 2008, respectively),
and is a joint venture between Denison (63.3% and operator), Cameco Corp. (“Cameco”) (26.7%), and JCU
(Canada) Exploration Company Limited (“JCU”) (10%).
A Pre-Feasibility Study (“PFS”) was initiated for the Wheeler River project in Q3’2016 and is expected to
be completed during 2018. Prior to initiation of th e PFS, a Preliminary Economic Assessment (“PEA”) was
completed in Q2’2016, which considered 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 then current long term contract price of
uranium (US$44.00 per pound U 3O8), and Denison's share of estimated initial capital expenditures
("CAPEX") of CAD$336M (CAD$560M on 100% basis).
The PEA is preliminary in nature and includes infer red mineral resources that are considered too
speculative geologically to have the economic considerations applied to them to be categorized as mineral
reserves, and there is no certainty that the prelim inary economic assessment will be realized. Mineral
resources are not mineral reserves and do not have demonstrated economic viability.
In January, 2017, Denison entered into an agreement with its Wheeler River Joint Venture partners,
Cameco and JCU, to fund 75% of Joint Venture expens es in 2017 and 2018 (ordinarily 60%) in exchange
for an increase in Denison's interest in the projec t to up to approximately 66%. Under the terms of th e
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. P ursuant to the agreement, as at December 31, 2017,
Denison had increased its interest in the Wheeler River project from 60% to 63.3%.
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About Denison
Denison is a uranium exploration and development company with interests focused in the Athabasca Basin
region of northern Saskatchewan, Canada. In additio n to its 63.3% owned Wheeler River project, which
ranks as the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of
the Athabasca Basin region, Denison's Athabasca Basin exploration portfolio consists of numerous projects
covering approximately 353,000 hectares. Denison's interests in Athabasca Basin also include a 22.5%
ownership interest in the McClean Lake joint ventur e (“MLJV”), which includes several uranium deposits
and the McClean Lake uranium mill, which is current ly processing ore from the Cigar Lake mine under a
toll milling agreement, plus a 25.17% interest in the Midwest and Midwest A deposits, and a 64.22% interest
in the J Zone deposit and Huskie discovery on the W aterbury Lake property. Each of Midwest, Midwest A,
J Zone and Huskie 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 c ontains forward-looking information
pertaining to the following: exploration (including drilling) and evaluation activities, plans and objectives; potential mineralization of drill
targets and identified trends; estimates of Denison's mineral resources and the results of its PEA; plans and objectives with respect to
updating its resource estimates and preparing a PFS to assess on a preliminary basis the potential for mine development an whether to
proceed with a detailed feasibility study; and Denison’s percentage interest in its properties and its plans and agreements with its joint
venture partners, as applicable. Statements relating to "mineral reserves" or "mineral resources" are deemed to be forward-looking
information, as they involve the implied assessment, based on certain estimates and assumptions that the mineral reserves and mineral
resources described can be profitably produced in the future.
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, uncertainties and other factors that may cause the actual results, level of activity, performance
or achievements of Denison to be materially different from those expressed or implied by forward-looking statements. Factors, such as
environmental impacts, stakeholder approvals, and capital needs can significant alter plans and achievements. Denison believes that the
expectations reflected in this forward-looking information are reasonable but no assurance can be given that these expectations will prove
to be accurate and may differ materially from those anticipated 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 factors discussed in Denison's Annual Information Form dated
March 27, 2018 under the heading "Risk Factors". These factors are not, and should not be construed as being exhaustive. Accordingly,
readers should not place undue reliance on forward-looking statements.
The forward-looking information contained in this press release is expressly qualified by this cautionary statement. Any forward-looking
information and the assumptions made with respect thereto speaks only as of the date of this press release. 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 Denison's 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.
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Figure 1: Location map of the Wheeler River property and the Phoenix and Gryphon deposits.
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Figure 2: Winter 2018 drill hole locations near Gryphon and along the K-North and K-West trends.