Eastmain Extends the Percival Discovery and Announces Winter 2019 Drill Program

TORONTO, Dec. 20, 2018 - Eastmain Resources Inc. (“Eastmain” or the “Company” - TSX:ER, OTCQX:EANRF) reports results for 5 holes (1,558 m) drilled in late 2018 at the Percival discovery (“Percival”) and presents its focused exploration program for 2019 on the 100%-owned Clearwater Property (the “Property”) in James Bay, Québec. The early 2019 exploration program will focus on testing the extent and continuity of the Percival discovery (see PR dated Nov. 13, 2018). Additionally, the program will evaluate the potential of the 14-km long Knight-Serendipity volcano-sedimentary Horizon (“KS Horizon”).

Percival is located 14 km ESE of the Company’s million-ounce Eau Claire gold deposit, within the 20-km long Cannard Deformation Zone (see FIGURE 1) and within the southern leg of the KS Horizon. Percival is a hydrothermal gold system hosted in a thick metasedimentary sequence with locally interbedded intermediate to felsic volcaniclastic rocks. Results from the new drilling provide a further understanding of the mineralization controls, namely by defining lithological and structural settings, within the host stratigraphy while identifying at least two gold mineralized zones within the metasedimentary package (see FIGURES 2-6).

Claude Lemasson, Eastmain President and CEO commented: “January will be a strong start to 2019 for Eastmain. With a new discovery at Clearwater and an improved geological and geophysical understanding in hand, our team is designing a focused exploration program that follows-up on our 2018 significant results. Percival represents a new style of gold mineralization on the property and we are excited to continue developing the discovery, as well as testing for new mineralization along the entire KS Horizon.”

Drilling Highlights include:

• ER18-828: 1.17 g/t Au over 18.3 m (vertical depth of 43 m), including 2.35 g/t Au over 8.0 m within the original targeted zone (silicified mudstone breccia)
• ER18-827: 0.71 g/t Au over 51.9 m (vertical depth of 177 m), including 2.69 g/t Au over 9.0 m in a new deeper zone (silicified greywacke with breccia interbeds and silicified mudstone breccia)

Project Highlights:

• Improved interpretation: Follow-up drilling focused on testing the Percival gold bearing zone, with holes drilled to the NE and SW of the discovery holes (ER18-822 and ER18-823). It extended the strike of the zone to a minimum length of 200 m and tested the 70^o SE dipping stratigraphy to approximately 250 m downdip.
• Geophysics Airborne Survey: Eastmain completed a Helicopter-borne VTEM™ and Horizontal Magnetic Gradiometer Geophysical Survey (VTEM Plus) along the KS Horizon (550 line-kms covering 12 kms of the KS Horizon) which includes the Percival discovery. Interpretation will be available in January and will help focus work at Percival and other prospective targets along the KS Horizon (see FIGURE 1).
• Improved infrastructure: A 14 km winter trail connecting the road-accessible Eau Claire Project and camp to the Percival discovery will be opened in January. The trail will provide improved access and cost efficiency for the winter campaign.
• 2019 Winter Drill Program: A three-month, 20-hole (5,500 m), focused drilling campaign is planned to begin in mid-January. The program is designed to expand on the discovery while further identifying gold mineralization controls and distribution within the argillite-mudstone sedimentary package at Percival. Building on a likely successful Winter Program, a second extensive campaign will be planned for the second half of 2019 and will include additional drilling of the discovery area and test additional targets delineated along the KS Horizon, using newly acquired geophysical and soil geochemistry information.

Drilling Results
Gold has been intersected in all holes testing for breccia units within the metasedimentary package which hosts the Percival gold mineralization. Discovery drill holes ER18-822 and ER18-823 traversed the most strongly mineralized portion drilled to date intersecting strongly silicified, sulfide rich, mineralized breccia zones where both matrix and clasts have been replaced by silica. The new holes confirm the lateral extent of potentially gold bearing breccias while intersecting less intense silicification and sulphide concentrations. Significant intercepts and hole location information are presented in Tables 1 and 2 below.

The type and intensity of alteration in the initial discovery holes suggests proximity to a syn-volcanic hydrothermal source. Preliminary interpretations strongly suggest that increases in breccia thickness, intensity of alteration (namely silicification) and to a lesser degree high sulphide content, are all controls that can be used to determine the extent, orientation, and occurrence of gold mineralization within the new zones to guide future drill testing. Oriented core measurements taken during the fall program will also assist with targeting gold bearing mineralization in the next phases of drilling.

Holes ER18-825 and ER18-828 highlight the absence of the mafic volcanic footwall seen in holes ER18-822 and others drilled further to the east. A NNW trending fault structure is magnetically inferred in this area and may represent a potential offset of stratigraphy and mineralization. One drill hole (assays pending) is testing this potential structure.

Table 1: Significant Intercepts

• Intervals are presented in core length; holes are generally planned to intersect mineralization as close to perpendicular to strike as possible; true widths are estimated to be 75% of downhole length when hole and dips of the mineralized horizons are considered.
• Assays presented are not capped. Intercepts occur within geological confines of major zones but have not been correlated to individual structures/horizons within these zones at this time.
• Vertical depth is measured from the surface to the mid-point of the reported interval.

Table 2: Drill Hole Information

Additional Drilling Completed and Planned

Three additional holes (887 m) were completed this week at Percival. All three holes were collared to the west of the discovery holes, aimed at testing interpreted lateral extension, structural interpretation and possible plunge of breccia units in the sedimentary host package. Results from these holes will be available in January 2019.

The Percival Discovery

Percival is located 14 km ESE of the Eau Claire deposit (see FIGURE 1) in the Knight sector of the KS Horizon, on the Clearwater Property. The KS Horizon is characterized by an extensive package of metasedimentary and metavolcanic rocks metamorphosed from upper greenschist to lower amphibolite facies. The horizon is also affected by deformation related to major crustal scale structures specifically the Cannard Deformation zone at the Percival discovery. The stratigraphy at the Percival comprises foliated, predominantly south facing metasedimentary rocks underlain by marine mafic metavolcanics.

The Knight sector is interpreted to be at the south-western end of the prospective volcano-sedimentary sequence. Holes ER18-822 and ER18-823 were drilled on a single section (see FIGURE 5) to undercut gold mineralization exposed in a sequence of silicified metavolcanics and metasediments during the Company’s summer surface exploration program. These two holes intersected a silicified, sulfide rich, and gold mineralized brecciated interval of approximately 50 m in true thickness which extends from surface to a minimum vertical depth of approximately 100 m.

Holes ER18-824 to ER18-828 were drilled to flank Percival discovery holes ER18-822 and ER18-823, testing for the extension of the brecciated units over a NE strike length of 200 m and across stratigraphy over 250 m.

For additional information on the Geology of the Percival Discovery and the KS Horizon, please visit: http://www.eastmain.com/projects/clearwaterexploration/.

To view Figures 1-6, please click on the following link: http://www.eastmain.com/_resources/news/Images/ER-181220-Percival.pdf.

This press release was compiled and reviewed by William McGuinty, P.Geo., Eastmain’s VP Exploration and Carl Corriveau, P.Geo., Eastmain’s Exploration Manager, both Qualified Persons under National Instrument 43-101.

Quality Assurance and Quality Control (QA/QC)
The design of the Eastmain Resources’ drilling programs, Quality Assurance/Quality Control and interpretation of results is under the control of Eastmain’s geological staff, including qualified persons employing a strict QA/QC program consistent with NI 43-101 and industry best practices. The Clearwater project is supervised by Eastmain’s Project Geologist, Michel Leblanc P. Geo.

Drill core is logged and split with half-core samples packaged and delivered to ALS Minerals laboratory. Samples are dried and subsequently crushed to 70% passing a 2 mm mesh screen. A 1,000 grams subsample is pulverized to a nominal 85% passing 75 micron mesh screen. The remaining crushed sample (reject) and pulverized sample (pulp) are retained for further analysis and quality control. All samples are analysed by Fire Assay with an Atomic Absorption (AA) finish using a 50 g aliquot of pulverized material. Assays exceeding 5 g/t Au are re‐assayed by Fire Assay with a Gravimetric Finish. Eastmain regularly inserts 3rd party reference control samples and blank samples in the sample stream to monitor assay performance and performs duplicate sampling at a second certified laboratory. Approximately 10% of samples submitted are part of the Company’s laboratory sample control protocols.

About Eastmain Resources Inc. (TSX:ER) www.eastmain.com
Eastmain is a Canadian exploration company advancing three high-grade gold assets in the emerging James Bay gold camp in Québec. The Company holds a 100% interest in the Eau Claire Project, for which it recently issued a Preliminary Economic Assessment (“PEA”), and the Eastmain Mine Project where the Company prepared a NI 43-101 Mineral Resource Estimate in 2018. Eastmain is also the manager of the Éléonore South Joint Venture, located immediately south of Goldcorp Inc.'s Éléonore Mine, which hosts a new high-grade gold discovery found in late 2017. In addition, the Company has a pipeline of exploration projects in this favourable mining jurisdiction with nearby infrastructure.

For more information:
Claude Lemasson, President and CEO
+1 647-347-3765
lemasson@eastmain.com

Alison Dwoskin, Manager, Investor Relations
+1 647-347-3735
dwoskin@eastmain.com

Forward-Looking Statements – Certain information set forth in this news release may contain forward-looking statements that involve substantial known and unknown risks and uncertainties. Forward-looking statements consist of statements that are not purely historical, including statements regarding beliefs, plans, expectations or timing of future plans, and include, but not limited to, statements with respect to the potential success of the Company’s future exploration and development strategies. These forward-looking statements are subject to numerous risks and uncertainties, certain of which are beyond the control of Eastmain, including, but not limited to the impact of general economic conditions, industry conditions, dependence upon regulatory approvals, the availability of financing, ‎timely completion of proposed studies and technical reports, and risks associated with the exploration, development and mining industry generally such as economic factors as they affect exploration, future commodity prices, changes in interest rates, safety and security, political, social or economic developments, environmental risks, insurance risks, capital expenditures, operating or technical difficulties in connection with development activities, personnel relations, the speculative nature of gold exploration and development, including the risks of diminishing quantities of grades of Mineral Resources, contests over property title, and changes in project parameters as plans continue to be refined. Readers are cautioned that the assumptions used in the preparation of such information, although considered reasonable at the time of preparation, may prove to be imprecise and, as such, undue reliance should not be placed on forward-looking statements. The Company assumes no obligation to update such information, except as may be required by law.