VANCOUVER, BRITISH COLUMBIA--(Marketwired - May 20, 2015) - Trevali Mining Corporation ("Trevali" or the "Company") (TSX:TV)(LMA:TV)(OTCQX:TREVF)(FRANKFURT:4TI) announces results of an independent mineral resource estimate update for its polymetallic Stratmat Deposit in the Bathurst Mining Camp of New Brunswick, Canada. Using a 5% ZnEq* cutoff, the resource estimate prepared by SRK Consulting (Canada) Inc., returned 4.70 million tonnes grading 5.31% zinc, 2.07% lead, 0.41% copper, 48.52 g/t silver and 0.59 g/t gold in the Indicated category and 2.40 million tonnes grading 4.76% zinc, 2.07% lead, 0.70% copper, 38.82 g/t silver and 0.42 g/t gold in the Inferred category (Table 1 & Figure 1).

The large Volcanogenic Massive Sulphide deposit consists of at least five discrete mineralized zones that span a distance of over 2 kilometres. The multi-lens, multi-zone deposit remains open for expansion at depth and the Company considers the exploration potential good-to-excellent (Figure 1).

"The resource estimate has successfully increased the Companies confidence in the Stratmat deposit and added significant new tonnage, all very important for the next phase as Trevali advances its growth plans for the Bathurst Mining Camp," stated Dr. Mark Cruise, Trevali's President and CEO.

The results from this SRK study will be incorporated into a planned Preliminary Economic Assessment update scheduled for later this year (Figure 2).

Table 1: 2015 Capped Indicated and Inferred Mineral Resources at the Stratmat Project at various Zn-equivalent cut-off grades, after SRK Consulting (Canada) Inc.

Cutoff		Tonnage	Grade						Contained Metal (M oz Au- Ag - M lbs Pb-Zn-Cu)
ZnEq %	Class	Million Tonnes	Au g/t	Ag g/t	Pb %	Zn %	Cu %	ZnEq %	Au	Ag	Pb	Zn	Cu
7	Indicated	2.15	0.70	60.70	2.71	6.75	0.41	9.34	0.05	4.19	128.18	319.28	19.39
	Inferred	0.88	0.50	50.90	3.05	6.91	0.57	9.84	0.01	1.45	59.46	134.71	11.11
5	Indicated	4.70	0.59	48.52	2.07	5.31	0.41	7.46	0.09	7.33	213.86	550.18	42.88
	Inferred	2.40	0.42	38.82	2.07	4.76	0.70	7.28	0.03	3.00	109.85	252.24	37.32
3	Indicated	9.16	0.49	37.09	1.50	3.99	0.42	5.74	0.14	10.9	302.76	806.06	84.84
	Inferred	5.70	0.36	27.32	1.33	3.22	0.77	5.33	0.07	5.01	167.69	404.47	97.27

*ZnEq= ((Cu Grade*Cu Price*Cu Recovery)+(Pb Grade*Pb Price*Pb Recovery)+(Zn Grade*Zn Price*Zn Recover+(Ag Grade*Ag Price*Ag Recovery))/Zn Price. In calculating ZnEq, SRK utilized the three year rolling average commodity prices. Price for Au is $1300 per ounce, Ag is $21.15 per ounce, Cu is $3.00 per pound, Pb is $1.00 per pound, and Zn is $1.00 per pound. A recovery of 88% was applied to Zn, 72% was applied to Pb, 50% was applied to Cu, 45% was applied to Ag, and 0% was applied to Au. The pounds of metal are in-situ and have not had any mining factors applied to them.

To view Figures 1 and 2, please visit the following link: http://media3.marketwire.com/docs/1008106_F1-2.pdf

DETAILS

Mineral resources were estimated by Dr. Gilles Arseneau, P. Geo. of SRK Consulting (Canada), Inc. an appropriate "independent qualified persons" as this term is defined in National Instrument 43-101. Dassault Systemes Geovia Gems® version 6.6 (Gems) software was used to review and modify the geological solids provided by Trevali, prepare assay data for geostatistical analysis, construct the block model, estimate metal grades and tabulate mineral resources. The Geostatistical Software SAGE2001was used for geostatistical analysis and variography.

The mineral resource incorporates the results of 339 core boreholes both historical and those drilled by Trevali. The original assay data was composited to 1.5-metre lengths, and then outliers were appropriately capped. Robust variography of the composited and capped data was possible for the Main and S1 Zones, where Ordinary Kriging was used to estimate resources. In the cases of the New, S0, and S5 Zones, variography was inconclusive; and Inverse Distance Squared was used to estimate mineral resources.

A density weighting factor was applied to the S0 and S1 Zones where sufficient data exists to support such weighting. The Main, New, and S5 Zones are not density weighted due to insufficient data.

Mineral resources were estimated into 5-by-5-by-5-metre blocks in multiple passes with successive passes only interpolating a block if it had not been estimated by a previous pass. Blocks were only estimated if at least two drill holes and 3 composites were found during passes one and two. A maximum of 12 composites were used to estimate a block grade. Pass one used a narrow search ellipse based on variography, and pass two used a wider search. During pass three, blocks that had at least two composites within the search ellipse were interpolated. Blocks interpolated during the first pass are categorized as indicated, and blocks interpolated during subsequent passes are categorized as inferred.

A detailed NI 43-101 report will be lodged on SEDAR and the Company's website within 45-days.

Qualified Person and Quality Control/Quality Assurance

EurGeol Dr. Mark D. Cruise, Trevali's President and CEO and Daniel Marinov, P.Geo, Trevali's Vice-President of Exploration, are qualified persons as defined by NI 43-101, have supervised the preparation of the scientific and technical information that forms the basis for this news release. Dr. Cruise is not independent of the Company, as he is an officer, director and shareholder. Mr. Marinov is not independent of the Company as he is an officer and shareholder. On-site personnel at the project rigorously collect and track samples which are then security sealed and shipped to Bureau Veritas Minerals Laboratories (BVML) preparation facility in Val D'Or, Quebec for crushing and splitting and coarse rejects were assayed at BVML in Vancouver, BC. BVML quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025: 1999. Analytical accuracy and precision are monitored by the analysis of reagent blanks, reference material and replicate samples. Quality control is further assured by the use of international and in-house standards. Blind certified reference material is inserted at regular intervals into the sample sequence by Trevali personnel in order to independently assess analytical accuracy. Finally, representative blind duplicate samples are routinely forwarded to an ISO compliant third party laboratory for additional quality control.

ABOUT TREVALI MINING CORPORATION

Trevali is a zinc-focused, base metals mining company with one producing operation in Peru and another currently undergoing commissioning in Canada.

In Peru, the Company is actively producing zinc and lead-silver concentrates from its 2,000-tonne-per-day Santander mine.

In Canada, Trevali owns the Caribou mine and mill, Halfmile mine and Stratmat deposit all located in the Bathurst Mining Camp of northern New Brunswick. The Company is currently commissioning its 3,000-tonne-per-day Caribou mine.

All of the Company's deposits remain open for expansion.

The common shares of Trevali are listed on the TSX (symbol TV), the OTCQX (symbol TREVF) and on the Lima Stock Exchange (symbol TV). For further details on Trevali, readers are referred to the Company's website (www.trevali.com) and to Canadian regulatory filings on SEDAR at www.sedar.com.

On Behalf of the Board of Directors of

TREVALI MINING CORPORATION

Mark D. Cruise, President

This news release contains "forward-looking statements" within the meaning of the United States private securities litigation reform act of 1995 and "forward-looking information" within the meaning of applicable Canadian securities legislation. Statements containing forward-looking information express, as at the date of this news release, the Company's plans, estimates, forecasts, projections, expectations, or beliefs as to future events or results and the company does not intend, and does not assume any obligation to, update such statements containing the forward-looking information. Such forward-looking statements and information include, but are not limited to statements as to: the accuracy of estimated mineral resources, anticipated results of future exploration, and forecast future metal prices, anticipated results of future electrical sales and expectations that environmental, permitting, legal, title, taxation, socio-economic, political, marketing or other issues will not materially affect estimates of mineral resources. These statements reflect the Company's current views with respect to future events and are necessarily based upon a number of assumptions and estimates that, while considered reasonable by the Company, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies.

These statements reflect the Company's current views with respect to future events and are necessarily based upon a number of assumptions and estimates that, while considered reasonable by the company, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be materially different from the results, performance or achievements that are or may be expressed or implied by such forward-looking statements contained in this news release and the company has made assumptions and estimates based on or related to many of these factors.

Such factors include, without limitation: fluctuations in spot and forward markets for silver, zinc, base metals and certain other commodities (such as natural gas, fuel oil and electricity); fluctuations in currency markets (such as the Peruvian sol versus the U.S. dollar); risks related to the technological and operational nature of the Company's business; changes in national and local government, legislation, taxation, controls or regulations and political or economic developments in Canada, the United States, Peru or other countries where the Company may carry on business in the future; risks and hazards associated with the business of mineral exploration, development and mining (including environmental hazards, industrial accidents, unusual or unexpected geological or structural formations, pressures, cave-ins and flooding); risks relating to the credit worthiness or financial condition of suppliers, refiners and other parties with whom the Company does business; inadequate insurance, or inability to obtain insurance, to cover these risks and hazards; employee relations; relationships with and claims by local communities and indigenous populations; availability and increasing costs associated with mining inputs and labour; the speculative nature of mineral exploration and development, including the risks of obtaining necessary licenses and permits and the presence of laws and regulations that may impose restrictions on mining,; diminishing quantities or grades of mineral resources as properties are mined; global financial conditions; business opportunities that may be presented to, or pursued by, the Company; the Company's ability to complete and successfully integrate acquisitions and to mitigate other business combination risks; challenges to, or difficulty in maintaining, the Company's title to properties and continued ownership thereof; the actual results of current exploration activities, conclusions of economic evaluations, and changes in project parameters to deal with unanticipated economic or other factors; increased competition in the mining industry for properties, equipment, qualified personnel, and their costs. Investors are cautioned against attributing undue certainty or reliance on forward-looking statements. Although the Company has attempted to identify important factors that could cause actual results to differ materially, there may be other factors that cause results not to be as anticipated, estimated, described or intended. The Company does not intend, and does not assume any obligation, to update these forward-looking statements or information to reflect changes in assumptions or changes in circumstances or any other events affecting such statements or information, other than as required by applicable law.

Trevali's production plans at the Caribou Mine, Halfmile and Stratmat projects, and Santander Mine are based only on Indicated and Inferred Mineral Resources and not Mineral Reserves and do not have demonstrated economic viability. Inferred Mineral Resources are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as Mineral Reserves, and there is therefore no certainty that the conclusions of the production plans and Preliminary Economic Assessment (PEA) will be realized. Additionally where Trevali discusses exploration/expansion potential, any potential quantity and grade is conceptual in nature and there has been insufficient exploration to define a mineral resource and it is uncertain if further exploration will result in the target being delineated as a mineral resource.

We advise US investors that while the terms "measured resources", "indicated resources" and "inferred resources" are recognized and required by Canadian regulations, the US Securities and Exchange Commission does not recognize these terms. US investors are cautioned not to assume that any part or all of the material in these categories will ever be converted into reserves.

This news release does not constitute an offer to sell or a solicitation of an offer to buy any of the securities in the United States. The securities described herein have not been and will not be registered under the United States Securities Act of 1933, as amended, or the securities laws of any state and may not be offered or sold within the United States, absent such registration or an applicable exemption from such registration requirements.

The TSX has not approved or disapproved of the contents of this news release.