Sienna Resources Announces Cobalt, Nickel, and Copper Mineralization Intercepted by Reconnaissance Drilling at Slattberg Project in Sweden

Vancouver, May 17, 2018 - Sienna Resources (TSXV: SIE) ("Sienna") is pleased to announce encouraging drill results from the recently completed 7 hole, 942 meter drill program at its Slättberg nickel-copper cobalt project in Sweden (see Table 1, below). Drill results from this initial drill program at Slättberg show several significant intercepts of nickel and cobalt mineralization in areas that are along strike and down dip from historic mine workings in the area. These results include 2.8 meters averaging 1.05% nickel and 1125 ppm cobalt and 0.79% copper in drill hole SIE-18-3, and 13.0 meters averaging 0.32% nickel and 340 ppm cobalt 0.28% and copper and 0.32 ppm platinum + palladium, including 2.35 meters averaging 0.87% nickel and 594 ppm cobalt and 0.35% copper and 0.73 ppm platinum + palladium in drill hole SIE-18-5. This serves as clear evidence that additional bodies of nickel, cobalt and PGE-rich sulfide mineralization exist in the area, and remain open at depth and along strike.

Hole SIE-18-3 was drilled to the east of the historic Myrgruvans Mine, in an area that was previously untested by drilling. However, magnetic surveys in early 2018 showed a strong anomaly in the area, which was generated by the nickel bearing pyrrhotite-rich mineralization intercepted by hole SIE-18-3. The target remains open along strike and at depth.

Hole SIE-18-4 was drilled in the vicinity of another strong magnetic anomaly, further to the west along the mining trend. Mining maps from the area showed historic workings extending to a depth of 40 m in the area. However, hole SIE-18-4 entered mine workings at 76.8 meters depth, and was lost when drilling could not continue through a stope. Thus, mining in the area continued to significantly greater depths than had been indicated by the historic records.

Hole SIE-18-5 was drilled from the same drill pad as SIE-18-4, but was set back 7.5 meters and drilled a steeper angle. The hole intercepted pyrrhotite-rich mineralization 13.0 meters averaging 0.32% nickel and 0.28% copper and 0.034% cobalt and 0.32 ppm platinum + palladium (true widths interpreted to be 55-65% of the interval). This confirmed the presence of mineralization extending below the mine workings, and the likely source of the magnetic anomaly. Further, the thickness of massive and semi-massive sulfide in hole SIE-18-5, along with brecciated textures suggest that the mineralization may be broadening at depth. The target remains open at depth and along strike.

Hole SIE-18-6 was intended to test another strong magnetic anomaly that lies further to the west of the magnetic anomaly targeted by holes SIE-18-4 and SIE-18-5, and likely represents an extension of that body of mineralization. However, hole SIE-18-06 deviated substantially from its intended target, and failed to test the magnetic anomaly. Thus, this target remains untested.

Jason Gigliotti, President of Sienna states, "We are pleased with the initial drilling results. We plan to continue to establish the origin of the positive indicators and focus on expanding the scope of the project in the summer."

Table 1:

Drill Hole	From (m)	To (m)	Length (m)	Ni %	Co ppm	Cu %	Pd+Pt ppm	Comments
SIE-18-3	52.8	55.6	2.8	1.05	1125	0.79	0.45	TD 118.4 m, Az 154°, Incl -43°, true width estimated to be 60-70% of reported interval
SIE-18-4	77.3	Hole lost in unmapped mining stope
SIE-18-5	114.7	116.2	1.5	0.29	484	0.67	0.37	TD 147.6m, Az 349°, Incl -69°, True width estimated to be 55-65%.
SIE-18-5	118.0	131.0	13.0	0.32	338	0.28	0.37	TD 147.6m, Az 349°, Incl -69°, True width estimated to be 55-65%.
including	118.0	124.6	6.6	0.45	500	0.36	0.42	TD 147.6m, Az 349°, Incl -69°, True width estimated to be 55-65%.
including	118.0	120.4	2.4	0.87	594	0.35	0.73	TD 147.6m, Az 349°, Incl -69°, True width estimated to be 55-65%.
SIE-18-7	90	90.65	0.65	0.20	250	0.25	0.14	TD 119.4m, Az 342°, Incl -57°, True width estimated to be 60-70%.

Drilling Locations

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About Sienna Resources Inc.:

The Slättberg Cobalt-Nickel-Copper Project consists of three adjacent exploration permits comprising approximately 12,733 contiguous acres.

Slättberg is located 25 kilometers northwest of Falun, Sweden. Slättberg is a historic mining camp hosting cobalt-nickel-copper rich massive sulfide mineralization that occurs within a two kilometer belt of historic nickel-copper mines. The Project contains drill defined massive sulfide mineralization that extends to ~100 meters in depth, and remains open for expansion at depth and along strike. The Project is accessible year round, with nearby rail, power and 5 smelters in the Nordic region. At least 16 historic mines are located on the property, with historic operations dating back to the late 1800's.

Mineralization at Slättberg is hosted by 1.8-1.9 Ga (Svecofennian) supracrustal rocks (metavolcanics and metasediments) located along the southwestern flank of a large gabbroic intrusive complex. The historic mines are positioned along an east-west trend of massive sulfide occurrences developed in and around a similarly oriented body of "leptite". This is a local term used to describe rhyolitic/felsic tuffaceous rocks commonly associated with sulfide mineralization in Bergslagen. Mafic and ultramafic rocks also occur in and around the mine workings.

Sweden is at the forefront of an exploration and development boom in the mining industry. The country's favorable business environment includes a low corporate income tax rate, a proactive geological survey, and broad public support for export-led resource extraction. Sweden has a long history of mining, and is host to some of Europe's largest active mines.

The technical contents of this release were approved by Greg Thomson, PGeo, a qualified person as defined by National Instrument 43-101.

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Contact Information
Tel: 1.604.646.6900
Fax: 1.604.689.1733
www.siennaresources.com
info@siennaresources.com

"Jason Gigliotti"
President, Director
Sienna Resources Inc.

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