Denison Reports Wheeler River Summer Assays Ahead of Resource Estimate

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TORONTO, ONTARIO–(Marketwired – Nov. 27, 2017) – Denison Mines Corp. (“Denison” or the “Company”) (TSX:DML) (NYSE MKT:DNN) (NYSE American:DNN) is pleased to report assay results from the 64 drill holes (totalling 29,823 metres) completed as part of the summer 2017 exploration program on the Company’s 60% owned Wheeler River project. The primary objectives of the summer exploration program were to increase the confidence of the Gryphon resource to an indicated level, and to expand the overall size of the estimated resources, ahead of an updated resource estimate scheduled for later in the year and the Pre-Feasibility Study (“PFS”) scheduled for 2018.

To view Figures 1 to 7, please visit the following link: http://media3.marketwire.com/docs/1105273figures.pdf

Highlight assay statistics from the summer 2017 drilling program include:

  • On average, assay grades (“U3O8“) were 39% higher than the previously reported preliminary radiometric probe grades (“eU3O8“) and grade x thickness (GT) values were 34% higher;
  • Of the 64 drill holes completed during the summer program, 58 of the drill holes (91%) intersected significant uranium mineralization (> 0.1% U3O8 over 1.0 metre);
  • Of the 44 drill holes targeting mineralization outside of the current resources estimated for the Gryphon deposit, 38 of these drill holes (86%) intersected significant uranium mineralization (> 0.1% U3O8 over 1.0 metre) with 28 drill holes (64%) intersecting high-grades (> 1.0% U3O8 over 1.0 metre).
  • The 20 drill holes, completed to increase the confidence of the current Gryphon resource to an indicated level, were all significantly mineralized (> 0.1% U3O8 over 1.0 metre), with 16 of these drill holes (80%) intersecting high-grades (> 1.0% U3O8 over 1.0 metre).

Dale Verran, Denison’s Vice President Exploration, commented, “The assay results confirm what has been a phenomenal season of drilling on the Wheeler River property. Results from the final round of definition drilling of the current inferred Gryphon resource did not disappoint and we have been very satisfied with the continuity and grade of the mineralization in comparison with the inferred block model. The summer program was highlighted by the expansion of high-grade within the D series lenses and the discovery and expansion of the E series lenses, both of which are located outside of the current resources estimated for Gryphon. We are looking forward to the independent resource estimate in accordance with NI43-101 in the coming weeks, which will include the results from an additional 141 drill holes completed at Gryphon since the maiden resource estimate in late 2015.”

Highlight results confirmed by assays from the summer drill program include:

  • Continued expansion of high-grade within the D series lenses: During the summer program, a significant lens of high-grade mineralization has been expanded and delineated in all directions amongst the D series lenses by infill and step-out drilling on an approximate 25 x 25 metres spacing. The high-grade lens is interpreted from 29 drill holes (12 drill holes from previous drill programs) and is estimated to measure up to 150 metres along strike, approximately 240 metres along dip, with interpreted true thicknesses between approximately 2 and 20 metres. All D series lens mineralization occurs outside of the current resources estimated for the Gryphon deposit. Highlight summer 2017 assay intersections include:
    • 3.5% U3O8 over 8.0 metres (WR-694)
    • 6.3% U3O8 over 3.0 metres (WR-621D2)
    • 4.7% U3O8 over 3.5 metres (WR-690D2)
    • 1.8% U3O8 over 5.5 meters (WR-657D1)
    • 6.4% U3O8 over 1.5 metres (WR-621D1)
    • 4.3% U3O8 over 2.0 metres (WR-657D3)
    • 8.5% U3O8 over 1.0 metres (WR-690D1)
    • 5.5% U3O8 over 1.5 metres (WR-638D4)
    • 2.8% U3O8 over 2.5 meters (WR-691)
  • Extension of the E series lenses: Mineralization was extended within the E series lenses both at the unconformity and in the underlying upper basement during the summer drill program. The high-grade unconformity and basement lenses are interpreted from 19 drill holes and are estimated to measure up to 80 metres and 350 metres along strike, respectively. The E series lenses also occur outside of the current resources estimated for the Gryphon deposit. Highlight summer 2017 assay intersections include:
    • 12.9% U3O8 over 3.0 metres (WR-689D3) (Unconformity)
    • 2.8% U3O8 over 7.0 metres (WR-670D2) (Unconformity)
    • 8.8% U3O8 over 1.5 metres (WR-646D2) (Upper basement)
    • 3.2% U3O8 over 3.0 metres (WR-636D3) (Upper basement)
    • 1.4% U3O8 over 7.5 metres (WR-646D4) (Upper basement)
  • Continued expansion of the A and B series lenses: Drill holes located approximately 25 metres down-dip and up-dip of the boundaries of the A and B series lenses, as defined by the current resources estimated for the Gryphon deposit, returned significant results with the potential to add additional indicated resources to the Gryphon deposit. Highlight summer 2017 assay intersections include:
    • 4.1% U3O8 over 6.5 metres (WR-582D3) (Gryphon Down Plunge, Up-Dip Area)
    • 3.5% U3O8 over 4.5 metres (WR-638D4) (Gryphon Down Plunge, Up-Dip Area)
    • 6.6% U3O8 over 3.0 metres (WR-681D3) (Gryphon Up Plunge, Down-Dip Area)
    • 1.7% U3O8 over 1.5 metres (WR-681AD2) (Gryphon Up Plunge, Down-Dip Area)
    • 1.6% U3O8 over 3.5 metres (WR-682D1) (Gryphon Up Plunge, Down-Dip Area)
    • 5.0% U3O8 over 5.5 metres (WR-624D3) (Gryphon Up Plunge, Up-Dip Area)
    • 2.3% U3O8 over 2.0 metres (WR-673D1) (Gryphon Up Plunge, Up-Dip Area)
  • Completion of the definition drilling program: Definition drilling designed to upgrade the current inferred resources estimated for the Gryphon deposit (A, B and C series lenses), to an indicated level of confidence, has been completed. A total program of 42 drill holes successfully reached their respective targets as part of definition drilling activities carried out through 2016 and 2017. The assay results show good consistency with the inferred grade model. Highlight summer 2017 assay intersections include:
    • 2.3 % U3O8 over 18.5 metres (WR-604D1)
    • 4.0% U3O8 over 6.0 metres and 5.8% U3O8 over 6.0 metres (WR-692)
    • 4.8% U3O8 over 6.0 meters (WR-564D1)
    • 1.8% U3O8 over 21.5 metres (WR-572D1)
    • 10.8% U3O8 over 4.0 meters (WR-564D3)
    • 4.1% U3O8 over 6.5 metres (WR-610D1)

Illustrative Figures and Further Details

A plan map of the Gryphon A, B, C, D and E series lenses is provided in Figure 1. The inset on Figure 1 shows a schematic cross section of the A, B, C, D and E series lenses and their respective inclined longitudinal section windows (as shaded rectangles). Figures 2 to 6 provide inclined longitudinal sections of the Gryphon A, B, C, D and E series lenses respectively. Figure 7 provides a plan map of the mineralization located at, or immediately above, the sub-Athabasca unconformity which forms part of the E series lenses.

The modelled mineralized lenses shown in Figures 1 to 6 are defined using a 0.05% U3O8 grade shell and minimum thickness of two metres, and have been updated only to the extent of the winter 2017 assay results. There is no certainty that the modelled mineralized lenses shown will constitute future mineral resources and they may be subject to modifications based on future interpretations or as further drilling data becomes available.

Further details regarding the Gryphon deposit and the current mineral resource estimates are provided in the NI 43-101 Technical Report for the Wheeler River project titled “Preliminary Economic Assessment for the Wheeler River Uranium Project, Saskatchewan, Canada” dated April 8, 2016 with an effective date of March 31, 2016. A copy of this report is available on Denison’s website and under its profile on SEDAR at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

Sampling and Assay Procedures

The Company currently reports preliminary radiometric equivalent grades (“eU3O8“), derived from a calibrated downhole total gamma probe, during its exploration programs and subsequently reports definitive assay grades following sampling and chemical analysis of the mineralized drill core.

Drill core with anomalous total gamma radioactivity (>300 counts per second) was sampled over 0.5 metre intervals. Sampling is undertaken on site by splitting the core in half, with one half submitted for analysis and the other half retained in the core box for future reference. Uranium assays are performed by the Saskatchewan Research Council (“SRC”) Geoanalytical Laboratories using an ISO/IEC 17025:2005 accredited method for the determination of U3O8 weight %. Sample preparation involves crushing and pulverizing core samples to 90% passing -106 microns. The resultant pulp is digested using aqua-regia and the solution analyzed for U3O8 weight % using ICP-OES. Core recovery at Gryphon is typically 100% and therefore radiometric equivalent U3O8 grades (“eU3O8“) are not required as a substitute for chemical U3O8 assays. In addition to internal checks by SRC Geoanalytical Laboratories, the Company has rigorous quality assurance and quality control (“QAQC”) procedures including the insertion of standard reference materials, blanks and field duplicates. The assay data is subject to verification procedures by qualified persons employed by Denison prior to disclosure. For further details on the assay, QAQC and data verification procedures please see Denison’s Annual Information Form dated March 23, 2017 filed under the Company’s profile on SEDAR (www.sedar.com).

Assay Results Tables

The following tables provide assay results assay results from the 64 drill holes completed as part of the summer 2017 exploration program on the Wheeler River project. Table 1 provides assay results for drill holes targeting the Gryphon D and E series lenses, Table 2 provides assay results for Gryphon deposit A and B expansion drill holes, and Table 3 provides assay results for Gryphon deposit A, B, C definition drill holes. The corresponding previously announced preliminary radiometric equivalent grades (“eU3O8“), derived from a calibrated downhole total gamma probe, are provided for comparison.

Table 1: Assay results for drill holes targeting the Gryphon D and E series lenses
Section Drill Hole From (m) To (m) Length (m)5 U3O8(%)
1,2,4		 Lens Designation Previously announced
eU3O8 result
5125GP WR-646D1 558.2 559.2 1.0 0.22 E Series 0.33% / 1 m
and 587.3 588.8 1.5 1.1 E Series 1% / 1.8 m
including3 587.3 588.3 1.0 1.4 E Series 1.4% / 1 m
and 687.1 688.1 1.0 0.34 D Series 0.36% / 1 m
5150GP WR-621D4 No significant mineralization
WR-621D5 751.4 752.4 1.0 0.11 D Series 0.11% / 1 m
WR-646D2 584.5 586.0 1.5 8.8 ESeries 4.6% / 1.5 m
WR-646D3 579.0 580.0 1.0 2.65 E Series Not probed
WR-646D3 584.5 587.5 3.0 3.16 E Series Not probed
including3 584.5 586.5 2.0 4.48 E Series Not probed
WR-646D4 558.0 559.0 1.0 0.19 E Series 0.15% / 1 m
and 578.5 581.0 2.5 0.22 E Series 0.27% / 1 m
and 585.5 593.0 7.5 1.4 E Series 1.1% / 7.6 m
including3 585.5 586.5 1.0 4.5 E Series 3.4% / 1 m
including3 590.0 591.5 1.5 3.2 E Series 2.1% / 1.5 m
and 663.2 664.2 1.0 0.20 E Series Below cut-off
and 666.8 667.8 1.0 0.13 E Series 0.15% / 1 m
and 700.2 701.2 1.0 4.9 D Series 4.4% / 1.1 m
WR-646D5 578.5 579.5 1.0 1.5 E Series 0.97% / 1.2 m
including3 578.5 579.5 1.0 1.5 E Series 1.1% / 1 m
and 585.5 586.5 1.0 0.32 E Series 0.14% / 1 m
5175GP WR-691 602.7 603.7 1.0 0.19 E Series Below cut-off
and 639.2 640.7 1.5 0.47 E Series 0.59% / 1 m
and 713.2 714.2 1.0 0.12 D Series 0.14% / 1 m
and 786.5 787.5 1.0 0.27 D Series 0.47% / 1 m
and 789.0 790.5 1.5 0.14 D Series 0.16% / 1.2 m
and 791.8 794.3 2.5 1.1 D Series 1% / 2.4 m
including3 793.3 794.3 1.0 2.6 D Series 2.1% / 1 m
and 796.8 797.8 1.0 0.16 D Series Below cut-off
and 802.1 803.1 1.0 0.21 D Series Below cut-off
and 805.5 806.5 1.0 0.59 D Series 0.43% / 1 m
and 811.3 813.8 2.5 2.8 D Series 2.8% / 2.3 m
including3 811.3 813.3 2.0 3.4 D Series 4.5% / 1.3 m
and 817.4 818.4 1.0 0.17 D Series 0.12% / 1 m
WR-694 565.5 566.5 1.0 0.10 E Series Below cut-off
and 567.0 568.5 1.5 0.22 E Series 0.11% / 1 m
and 708.5 709.5 1.0 0.23 D Series 0.27% / 1 m
and 718.0 726.0 8.0 3.5 D Series 0.62% / 2.7 m
5200GP WR-621D1 704.0 705.0 1.0 0.10 D Series Below cut-off
and 753.9 755.4 1.5 6.4 D Series 3.2% / 2 m
including3 753.9 754.9 1.0 9.5 D Series 6.1% / 1 m
and 763.0 764.5 1.5 1.4 D Series 0.62% / 2.5m
including3 763.5 764.5 1.0 1.7 D Series 1.2% / 1 m
WR-621D2 754.0 757.0 3.0 6.3 D Series 3.5% / 3.2 m
including3 755.0 757.0 2.0 9.1 D Series 4.1% / 2.7 m
and 764.0 766.5 2.5 0.56 D Series 0.34% / 2.7 m
WR-621D3 736.5 737.5 1.0 0.18 D Series 0.26% / 1 m
and 762.2 763.2 1.0 0.31 D Series 0.24% / 1 m
and 766.0 767.0 1.0 0.22 D Series 0.27% / 1 m
WR-689D2 545.5 547.5 2.0 0.52 E Series6 0.32% / 1.4 m
and 564.8 565.8 1.0 0.35 E Series 0.46% / 1 m
and 675.5 676.5 1.0 0.17 D Series 0.23% / 1m
and 680.3 681.3 1.0 1.8 D Series 1% / 1.1 m
and 687.3 689.3 2.0 1.2 D Series 0.55% / 2.5 m
Including3 688.3 689.3 1.0 2.1 D Series 1.1% / 1 m
and 694.1 695.1 1.0 1.3 D Series 1.2% / 1 m
and 697.7 698.7 1.0 2.3 D Series 2.3% / 1 m
WR-689D3 549.0 552.0 3.0 12.9 E Series6 5% / 4.7 m
including3 549.0 551.5 2.5 15.4 E Series6 8.5% / 2.7 m
and 565.2 566.2 1.0 0.42 D Series 0.2% / 1 m
5225GP WR-650D1 671.6 672.6 1.0 0.25 A Series 0.3% / 1.1 m
WR-654D1 722.2 723.2 1.0 0.96 D Series 0.7% / 1.9 m
and 736.5 737.5 1.0 0.14 D Series 0.12% / 1 m
and 742.7 744.2 1.5 4.0 D Series 4.3% / 1.2 m
including3 742.7 743.7 1.0 5.9 D Series 5.1% / 1 m
and 758.1 759.1 1.0 0.19 D Series 0.18% / 1 m
WR-690D1 618.5 620.0 1.5 0.25 E Series 0.17% / 1.4 m
and 695.9 697.9 2.0 0.62 D Series 0.48% / 2 m
and 718.4 719.4 1.0 4.5 D Series 1.5% / 2 m
and 724.9 725.9 1.0 8.5 D Series 6.4% / 1 m
WR-690D2 566.0 567.0 1.0 0.67 E Series 0.9% / 1.5 m
and 686.8 687.8 1.0 0.85 D Series 0.5% / 1 m
and 694.5 695.5 1.0 0.16 D Series 0.1% / 1 m
and 701.0 702.0 1.0 1.1 D Series 0.6% / 1 m
and 711.5 715.0 3.5 4.7 D Series 3.8% / 3.7 m
and 718.0 719.0 1.0 1.1 D Series 0.4% / 3.5 m
and 721.0 722.0 1.0 0.18 D Series Below cut-off
WR-690D3 558.7 560.2 1.5 0.95 E Series6 1.2% / 1.4 m
including3 559.2 560.2 1.0 1.3 E Series 1.6% / 1 m
and 573.3 574.3 1.0 0.34 E Series 0.75% / 1 m
and 657.5 658.5 1.0 0.19 D Series 0.12% / 1 m
5250GP WR-657D1 567.5 568.5 1.0 0.38 E Series 0.22% / 1.5 m
and 708.8 714.3 5.5 1.8 D Series 2% / 5.2 m
including3 709.3 712.3 3.0 3.1 D Series 3.1% / 3.1 m
WR-657D3 561.7 566.2 4.5 0.68 E Series6 0.86% / 2.2 m
including3 564.7 565.7 1.0 2.6 E Series 1.7% / 1 m
and 693.7 694.7 1.0 0.55 D Series 0.92% / 1 m
and 701.6 702.6 1.0 2.7 D Series 2% / 1.3 m
5275GP WR-657D2 586.5 587.5 1.0 0.29 E Series 0.2% / 1 m
and 680.8 682.8 2.0 4.3 D Series 1.6% / 2.5 m
WR-670D2 543.0 550.0 7.0 2.8 E Series6 2.8% / 7 m
including3 543.5 549.0 5.5 3.4 E Series6 4.3% / 4.3 m
WR-670D2 569.2 570.2 1.0 1.1 E Series 0.39% / 1 m
and 618.2 619.2 1.0 0.12 E Series Below cut-off
and 681.1 682.1 1.0 0.19 D Series 0.18% / 1 m

Notes:

  1. U3O8 is the chemical assay of mineralized split core samples.
  2. Intersection interval is composited above a cut-off grade of 0.05% U3O8 unless otherwise indicated.
  3. Intersection interval is composited above a cut-off grade of 1.0% U3O8.
  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 the northwest the true thickness of both the basement and unconformity mineralization is expected to be approximately 75% of the intersection lengths (the basement mineralization is interpreted to dip moderately to the southeast and the unconformity mineralization is interpreted to be flat-lying).
  6. Unconformity intersection.
Table 2: Assay results for Gryphon deposit A and B expansion drill holes
Section Drill Hole From (m) To (m) Length (m)5 U3O8(%)
1,2,4		 Lens Designation Previously announced eU3O8 result
4775GP WR-679D1 No significant mineralization Below cut-off
4800GP WR-584BD2 632.8 633.8 1.0 0.22 B Series 0.11% / 1 m
4875GP WR-580D2 No significant mineralization Below cut-off
WR-642D1 No significant mineralization Below cut-off
4900GP WR-580D1 613.5 615.0 1.5 0.14 A Series 0.16% / 1.4 m
WR-681AD1 No significant mineralization Below cut-off
4925GP WR-673D1 613.7 615.7 2.0 2.3 A Series 1.1% / 2.9 m
including3 614.7 615.7 1.0 3.9 A Series 2.8% / 1 m
and 697.7 698.7 1.0 0.26 C Series 0.28% / 1 m
WR-681AD2 699.3 700.3 1.0 0.36 A Series 0.26% / 1 m
and 718.5 720.5 2.0 1.0 A Series 1.3% / 1.6 m
including3 719.5 720.5 1.0 1.8 A Series 1.9% / 1 m
and 723.1 724.1 1.0 0.14 A Series Below cut-off
and 726.4 727.9 1.5 1.7 A Series 1.7% / 1.6 m
including3 726.9 727.9 1.0 2.2 A Series 2.2% / 1.1 m
and 786.1 787.1 1.0 0.44 C Series 0.54% / 1 m
WR-681D3 702.3 703.3 1.0 0.13 A Series Below cut-off
and 705.8 708.8 3.0 0.98 A Series 0.41% / 3.4 m
including3 705.8 706.8 1.0 1.4 A Series Merged with interval above
including3 707.8 708.8 1.0 1.3 A Series Merged with interval above
and 713.8 716.8 3.0 6.6 A Series 4% / 3.1 m
including3 714.8 716.8 2.0 9.6 A Series 6.9% / 1.7 m
and 724.3 725.3 1.0 0.42 B Series 0.29% / 1 m
and 781.9 782.9 1.0 0.39 C Series 0.29% / 1 m
4950GP WR-682D1 759.3 760.3 1.0 0.12 A Series 0.12% / 1 m
and 762.3 765.8 3.5 1.6 A Series 1.3% / 3.6 m
including3 763.8 765.3 1.5 3.5 A Series 2.8% / 1.4 m
4975GP WR-693 No significant mineralization
5000GP WR-624D3 631.0 632.0 1.0 0.47 A Series 0.2% / 1 m
and 636.0 640.0 4.0 0.61 A Series 0.54% / 3.8 m
including3 637.0 638.0 1.0 1.4 A Series 1.3% / 1 m
and 660.5 666.0 5.5 5.0 B Series 4% / 5.2 m
including3 663.5 665.5 2.0 12.9 B Series 9.3% / 2.1 m
and 669.0 670.0 1.0 0.33 B Series 0.28% / 1.1 m
and 721.0 722.0 1.0 0.52 C Series 0.4% / 1 m
and 738.5 741.5 3.0 0.95 C Series 0.69% / 2.6 m
5025GP WR-560D2 675.0 676.0 1.0 0.57 B Series 0.38% / 1 m
and 728.0 731.0 3.0 0.21 C Series 0.13% / 1.3 m
and 745.0 746.0 1.0 0.12 C Series 0.16% / 1 m
WR-560D2 748.0 755.0 7.0 0.75 C Series 0.76% / 6.9 m
including3 748.0 749.0 1.0 1.4 C Series 1% / 1 m
including3 750.5 751.5 1.0 2.0 C Series 2% / 1 m
5075GP WR-568D3 718.0 719.5 1.5 0.14 A Series Below cut-off
and 726.0 728.5 2.5 0.14 A Series 0.14% / 1 m
and 753.0 754.5 1.5 0.76 C Series 0.54% / 1.3 m
5125GP WR-600D2 724.2 725.7 1.5 0.34 A Series 0.35% / 1.9 m
and 728.7 729.7 1.0 0.25 B Series 0.2% / 1 m
and 731.9 733.4 1.5 0.17 B Series 0.12% / 1.2 m
and 741.0 743.0 2.0 0.21 B Series 0.11% / 2.1 m
5150GP WR-600D3 710.5 711.5 1.0 0.12 A Series 0.21% / 4.1 m
and 712.0 715.0 3.0 0.25 A Series Merged with interval above
and 719.0 720.0 1.0 0.11 A Series Below cut-off
and 721.0 722.0 1.0 0.25 A Series 0.21% / 1 m
and 729.5 730.5 1.0 0.21 B Series Below cut-off
and 732.5 737.0 4.5 0.15 B Series 0.18% / 1.1 m
and 738.5 739.5 1.0 0.14 B Series 0.16% / 1 m
5175GP WR-638D1 716.5 717.5 1.0 0.10 A Series Below cut-off
and 725.1 726.5 1.4 0.42 A Series 0.22% / 1.8 m
and 729.0 730.0 1.0 0.32 A Series 0.21% / 1 m
and 731.4 732.4 1.0 0.11 A Series Below cut-off
and 787.5 788.5 1.0 0.410 D Series 0.85% / 1.1 m
5200GP WR-582D3 742.0 748.5 6.5 4.1 A Series 1.7% / 8.6 m
and 757.5 758.5 1.0 0.15 A Series 0.16% / 1 m
and 806.4 807.4 1.0 3.9 D Series 2.3% / 1 m
WR-638D3 710.5 711.5 1.0 0.25 A Series 0.37% / 1.4 m
and 716.5 717.5 1.0 0.33 A Series 0.24% / 1 m
and 766.1 767.1 1.0 0.13 D Series Below cut-off
and 771.8 772.8 1.0 0.19 D Series 0.11% / 1 m
and 776.4 777.4 1.0 0.12 D Series Below cut-off
and 778.4 779.4 1.0 0.79 D Series 0.44% / 4.1 m
and 779.9 780.9 1.0 0.12 D Series Below cut-off
5225GP WR-582D4 745.7 749.2 3.5 0.28 A Series 0.24% / 2.3 m
and 763.6 764.6 1.0 0.11 A Series 0.1% / 1 m
and 798.7 799.7 1.0 0.47 D Series 0.28% / 1 m
and 815.0 817.0 2.0 0.68 D Series 0.81% / 1.8 m
including3 815.5 816.5 1.0 1.1 D Series 1.2% / 1 m
WR-638D4 710.7 715.2 4.5 3.5 A Series 1.5% / 4.6 m
including3 712.7 715.2 2.5 5.9 A Series 2.5% / 2.6 m
including3 772.7 773.7 1.0 1.7 D Series 1.3% / 1 m
and 773.2 774.7 1.5 1.6 D Series 0.69% / 2.8 m
and 776.9 777.9 1.0 0.65 D Series 0.46% / 1 m
and 787.2 788.7 1.5 5.5 D Series 3.3% / 1.8 m
including3 787.2 788.2 1.0 8.1 D Series 5.1% / 1.1 m

Notes:

  1. U3O8 is the chemical assay of mineralized split core samples.
  2. Intersection interval is composited above a cut-off grade of 0.05% U3O8unless otherwise indicated.
  3. Intersection interval is composited above a cut-off grade of 1.0% U3O8.
  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 the 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.
Table 3: Assay results for Gryphon deposit A, B, C definition drill holes
Section Drill Hole From (m) To (m) Length (m)5 U3O8(%)
1,2,4		 Lens Designation Previously announced eU3O8 result
4925GP WR-567D3 665.1 666.1 1.0 0.15 A Series Below cut-off
and 681.1 682.1 1.0 0.14 A Series 0.1% / 1 m
and 690.5 698.5 8.0 1.8 A Series 1.7% / 8 m
including3 691.0 692.0 1.0 6.1 A Series 7% / 1 m
including3 695.0 696.0 1.0 6.3 A Series 4.1% / 1 m
including3 697.5 698.5 1.0 1.4 A Series 1.6% / 1 m
and 705.7 706.7 1.0 0.25 B Series 0.14% / 2.2 m
WR-572D2 659.4 660.4 1.0 0.15 A Series 0.41% / 6.2 m
and 662.9 665.4 2.5 0.44 A Series Merged with interval above
and 700.3 701.3 1.0 0.19 B Series 0.55% / 1 m
and 713.5 714.5 1.0 0.43 C Series 0.25% / 2.6 m
WR-692 708.5 714.5 6.0 4.0 A Series 2.3% / 6.5 m
including3 712.0 713.0 1.0 21.3 A Series 11.3% / 1.1 m
and 738.3 739.3 1.0 1.1 B Series 0.37% / 1 m
and 741.9 742.9 1.0 0.33 B Series 0.57% / 2.6 m
and 747.4 753.4 6.0 5.8 B Series 4.1% / 5.9 m
4950GP WR-572D4 642.3 643.3 1.0 0.97 A Series 0.78% / 1 m
and 644.8 645.8 1.0 0.10 A Series 0.11% / 1 m
and 657.5 658.5 1.0 0.28 B Series 0.38% /1 m
and 665.9 667.9 2.0 0.44 B Series 0.21% / 1.9 m
and 707.1 708.1 1.0 0.31 C Series 0.19% / 1 m
4975GP WR-564D1 694.8 695.8 1.0 0.24 A Series 0.11% / 1 m
and 702.8 703.8 1.0 0.54 A Series 0.49% / 1 m
and 711.0 712.0 1.0 1.2 A Series 1.6% / 1.1 m
and 719.4 726.4 7.0 1.1 A Series 0.92% / 7.6 m
including3 719.4 720.4 1.0 2.4 A Series 2.7% / 1 m
including3 723.4 724.4 1.0 4.1 A Series 2.3% / 1 m
and 731.3 732.8 1.5 0.36 A Series 0.21% / 1.5 m
and 743.3 749.3 6.0 4.8 B Series 2.3% / 9.3 m
including3 743.8 744.8 1.0 1.0 B Series Below cut-off
including3 746.8 749.3 2.5 10.5 B Series 7.9% / 2.2 m
and 751.4 752.4 1.0 2.1 B Series Below cut-off
and 755.4 756.4 1.0 0.59 B Series 0.3% / 1 m
WR-572D1 641.5 663.0 21.5 1.8 A Series 1.3% / 21.8 m
including3 653.0 654.0 1.0 3.7 A Series 2.5% / 1.2 m
including3 657.5 662.5 5.0 5.9 A Series 3.9% / 5.3 m
and 686.4 693.9 7.5 0.46 B Series 0.48% / 8.6 m
including3 690.4 691.4 1.0 1.2 B Series 1.7% / 1 m
including3 692.9 693.9 1.0 1.1 B Series 1.2% / 1 m
WR-572D3 644.2 645.2 1.0 0.24 A Series 0.23% / 1.1 m
and 670.0 671.0 1.0 0.11 B Series 0.17% / 1 m
WR-624D2 632.8 633.8 1.0 0.26 A Series 0.32% / 1 m
and 647.8 651.3 3.5 1.1 A Series 1.1% / 3.4 m
including3 649.8 651.3 1.5 1.9 A Series 2.7% / 1 m
and 670.0 671.0 1.0 0.39 B Series 0.33% / 1.1 m
and 677.8 678.8 1.0 0.33 B Series 0.46% / 1.2 m
and 731.8 733.8 2.0 1.5 C Series 1% / 1.6 m
including3 732.8 733.8 1.0 2.8 C Series 1.6% / 1 m
5000GP WR-578D1 707.5 708.5 1.0 0.63 A Series 0.59% / 1 m
and 722.0 723.0 1.0 0.19 A Series Below cut-off
and 758.5 760.0 1.5 3.4 A Series 2.5% / 1.7 m
including3 759.0 760.0 1.0 4.9 A Series 3.9% / 1 m
including3 767.5 768.5 1.0 1.1 B Series Below cut-off
and 768.0 771.0 3.0 0.43 B Series 0.42% / 1.2 m
WR-624D1 632.4 633.4 1.0 1.1 A Series 0.79% / 1 m
and 641.6 642.6 1.0 0.75 A Series 0.31% / 1 m
and 656.8 657.8 1.0 0.76 A Series 0.83% / 1 m
and 660.3 661.8 1.5 0.93 A Series 1% / 1.7 m
including3 660.3 661.3 1.0 1.3 A Series 1.6% / 1 m
and 666.3 670.3 4.0 0.90 A Series 0.57% / 4.1 m
including3 667.3 668.3 1.0 2.7 A Series 1.3% / 1 m
and 694.6 696.6 2.0 0.13 B Series 0.31% / 3.7 m
and 698.1 700.1 2.0 0.24 B Series Below cut-off
and 741.9 745.9 4.0 0.52 C Series 0.56%/ 4.5 m
and 750.1 752.6 2.5 0.28 C Series 0.69% / 2.3 m
and 801.5 803.5 2.0 0.45 D Series 0.23% / 2.1 m
5025GP WR-560D1 669.5 672.0 2.5 0.46 A Series 0.39% / 2.8 m
and 675.0 676.0 1.0 0.18 A Series 0.24% / 1 m
and 720.6 721.6 1.0 0.62 B Series 0.24% / 1 m
and 755.5 756.5 1.0 0.11 C Series Below cut-off
and 759.5 760.5 1.0 6.8 C Series 3.8% / 1.2 m
WR-564D2 721.4 722.4 1.0 0.85 A Series 0.37% / 1 m
and 731.1 732.6 1.5 0.81 A Series 0.38% / 1.7 m
and 737.3 741.8 4.5 2.3 A Series 1.8% / 3.9m
including3 737.3 738.8 1.5 6.4 A Series 3.2% / 2 m
WR-564D3 708.0 709.0 1.0 0.40 A Series 0.18% / 1 m
and 718.0 722.0 4.0 10.8 A Series 5.8% / 5.4 m
including3 719.0 721.5 2.5 17.0 A Series 11% / 2.8 m
and 742.5 743.5 1.0 0.21 B Series 0.61% /5.4 m
and 746.5 747.5 1.0 0.33 B Series Below cut-off
and 751.0 752.0 1.0 0.21 B Series 0.16% / 1 m
and 759.0 764.0 5.0 0.26 C Series 0.3% / 5.2 m
and 768.5 772.5 4.0 0.61 C Series 0.36% / 1 m
including3 771.5 772.5 1.0 1.9 C Series Below cut-off
WR-568D2 757.0 758.5 1.5 0.18 C Series 0.19% / 2 m
and 761.5 762.5 1.0 0.11 C Series Below cut-off
5050GP WR-571D3 732.4 739.9 7.5 2.6 A Series 2.3% / 6.5 m
including3 733.9 737.9 4.0 4.8 A Series 3.3% / 4.4 m
and 741.9 743.4 1.5 0.13 A Series Below cut-off
and 744.9 745.9 1.0 0.12 A Series Below cut-off
and 761.0 762.0 1.0 7.6 B Series 3.4% / 1.6 m
and 763.9 764.9 1.0 0.18 B Series 0.12% / 1 m
and 769.9 770.9 1.0 0.12 C Series Below cut-off
and 776.9 777.9 1.0 0.24 C Series 0.25% / 1 m
5075GP WR-568D1 717.8 718.8 1.0 0.23 A Series Below cut-off
and 728.8 734.8 6.0 0.29 A Series 0.17% / 6.1 m
and 740.8 743.3 2.5 0.46 B Series 0.16% / 4 m
WR-570D1 747.0 751.5 4.5 1.7 A Series 0.92% / 7.7 m
including3 748.5 751.5 3.0 2.3 A Series 1.5% / 2.8 m
and 754.5 755.5 1.0 0.24 A Series 0.13% / 1 m
and 757.0 758.0 1.0 0.15 B Series 0.1% / 1 m
and 763.5 764.5 1.0 0.17 B Series Below cut-off
and 769.0 775.0 6.0 2.9 B Series 1.9% / 8.4 m
and 786.5 787.5 1.0 0.22 C Series 0.18% / 1.1 m
WR-604D1 765.5 767.0 1.5 3.4 A Series 1.2% / 1.5 m
including3 765.5 766.5 1.0 4.9 A Series 1.7% / 1 m
and 769.5 770.5 1.0 0.11 A Series Below cut-off
including3 771.0 772.0 1.0 3.1 A Series 1.3% / 1.2 m
and 771.0 789.5 18.5 2.3 A Series 1.2% / 1.5 m
including3 775.5 776.5 1.0 2.5 A Series 1% / 1 m
including3 780.0 788.5 8.5 3.8 A Series 3.3% / 7.8 m
and 792.0 795.5 3.5 0.41 A Series Merged with interval above
and 799.0 803.5 4.5 0.49 B Series 1.3% / 2.5 m
including3 800.0 801.0 1.0 1.2 B Series 1.9% / 1.5 m
WR-610D1 513.5 515.0 1.5 0.22 A Series 0.24% / 1.2 m
and 752.1 753.1 1.0 0.11 A Series 0.11% / 1 m
and 800.9 807.4 6.5 4.1 B Series 3% / 7 m
including3 801.4 807.4 6.0 4.4 B Series 3.6% / 5.7 m
5100GP WR-606D3 784.5 788.0 3.5 0.71 A Series 0.32% / 4.3 m
including3 786.5 787.5 1.0 1.8 A Series Below cut-off
and 792.5 806.5 14.0 0.90 B Series 0.63% / 15.2 m
including3 792.5 797.0 4.5 1.7 B Series 4.3% / 1 m
including3 799.5 800.5 1.0 3.1 B Series 1.6% / 1 m

Notes:

  1. U3O8 is the chemical assay of mineralized split core samples.
  2. Intersection interval is composited above a cut-off grade of 0.05% U3O8 unless otherwise indicated.
  3. Intersection interval is composited above a cut-off grade of 1.0% U3O8.
  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 the 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.

Qualified Persons

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 reviewed and approved the technical information contained in this release.

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 between 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 currently estimated to contain inferred resources of 43.0 million pounds U3O8 (above a cut-off grade of 0.2% U3O8) based on 834,000 tonnes of mineralization at an average grade of 2.3% U3O8. The Phoenix unconformity deposit is located approximately 3 kilometres to the southeast of Gryphon and is estimated to include indicated resources of 70.2 million pounds U3O8 (above a cut-off grade of 0.8% U3O8) based on 166,000 tonnes of mineralization at an average grade of 19.1% U3O8, 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 potential economic merit of co-developing the high-grade Gryphon and Phoenix deposits as a single underground mining operation. The PEA returned a base case pre-tax Internal Rate of Return (“IRR”) of 20.4% based on the current long term contract price of uranium (US.00 per pound U3O8), and Denison’s share of estimated initial capital expenditures (“CAPEX”) of CAD6M (CAD0M on 100% ownership basis). Exploration results from the subsequent drilling programs have not been incorporated into the resource estimate or the PEA. The PEA is preliminary in nature and includes inferred 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 preliminary economic assessment will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability. On July 19th, 2016 Denison announced the initiation of a Pre-Feasibility Study (“PFS”) for the Wheeler River property and the complimentary commencement of an infill drilling program at the Gryphon deposit to bring the inferred resources to an indicated level of confidence.

As previously announced on January 10, 2017, Denison has entered into an agreement with its Wheeler River Joint Venture partners, Cameco and JCU, to fund 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, Canada. In addition to 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 approximately 347,000 hectares in the Athabasca Basin region, including 327,000 hectares in the infrastructure rich eastern portion of the Athabasca Basin. Denison’s interests in Saskatchewan also include a 22.5% ownership interest in the McClean Lake joint venture (“MLJV”), which includes several uranium deposits and the McClean Lake 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 and Midwest A deposits, and a 64.22% interest in the J Zone deposit and Huskie discovery on the Waterbury 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.

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 and similar Canadian legislation concerning the business, operations and financial performance and condition of Denison.

Generally, these 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 activities, plans and objectives; potential mineralization of drill targets; the 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; and Denison’s percentage 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. 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 23, 2017 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.

David Cates
President and Chief Executive Officer
(416) 979-1991 ext. 362

Sophia Shane
Investor Relations
(604) 689-7842

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