Name of the Mine
Sunshine mine.

Location
Shoshone County, northern Idaho, US, in the Coeur d’Alene mining district, also known as the Silver Valley.

Mine Owner/s
Silver Opportunity Partners, a private, wholly owned subsidiary of Sunshine Silver Mining & Refining Corporation (SSMRC).

Brief Description
Sunshine is a brownfield, high-grade, primary silver mine and processing complex that is currently on care and maintenance. The is considered one of the world’s highest-grade primary silver projects. The asset includes the previously producing underground mine, processing plant and surface facilities.

The mine forms part of the broader Sunshine Complex, which also includes the Sunshine silver/copper refinery and historical antimony refinery grounds. The Jewell shaft is currently the only access into and out of the underground mine, and the mine is flooded to about the 3400 Level.

It has also digitised more than a century of geological records into the first three-dimensional model in the mine’s history and expanded the land package nearly fourfold.

Brief History
The Sunshine property was staked in 1884 and operated for more than 100 years under various owners.

Mine operations ceased in 2001, resumed briefly in 2008 and since then has been maintained on care and maintenance.

Primary Metals/Minerals
Silver

Secondary Metals/Minerals
Copper, lead, zinc and antimony have been produced historically. Other reported minerals include silver-bearing galena, pyrite, stibnite and arsenopyrite.

Geology/Mineralisation
Sunshine is a clastic metasediment-hosted, lead/silver/zinc mesothermal vein deposit within the Coeur d’Alene mining district. The district is hosted in Precambrian metasedimentary rocks of the Belt Supergroup. At Sunshine, mineralisation is mainly hosted in the St Regis Formation and the upper part of the underlying Revett Formation. These units comprise mainly argillite, siltite and quartzite, and have been folded, faulted and metamorphosed to greenschist facies.

The dominant veins generally strike east to west and dip steeply to the south, commonly at more than 60°. Mineralised veins generally range from 0.3 m to 1.5 m thick, with pinching and swelling along strike. Individual veins have been tested over strike lengths of up to 4 km, and veins can extend from surface to more than 1.6 km. More than 36 veins have been named and mined at Sunshine. The main mineralisation comprises tetrahedrite, freibergite, galena and sphalerite, with gangue minerals including siderite, quartz, pyrite and magnetite.

Reserves
None stated.

Resources
The Sunshine mine underground mineral resource estimate as at February 24, 2026, comprises no measured resources; indicated resources of 3.485-million tons grading 29.8 oz/t silver and inferred resources of 7.061-million tons grading 22.6 oz/t silver.

Type of Mine
Sunshine is an underground, narrow-vein, brownfield silver mine.

Mining Method
The ‘S-K 1300 Technical Report Summary on the Initial Assessment’ considers a combination of conventional cut-and-fill stoping and longhole stoping, selected for the narrow vein widths and steep dips of about 60° to 70°.

Major Infrastructure/Equipment
Sunshine has extensive historical underground workings, including shafts, winzes, adits, drifts, raises and ramps.

Major infrastructure includes shafts, hoists, compressors, dewatering systems, electrical distribution infrastructure, underground rail, compressed-air and water systems, communications, a tailings storage facility and surface facilities.

The construction  of new concentrator on the site of the existing concentrator building is envisaged. The proposed processing facility would produce silver/copper and lead/silver concentrates, with tailings used for paste backfill where possible and excess tailings filtered for dry-stack storage.

Prospects
SSMRC is advancing Sunshine as a restart and resource-growth opportunity, with the company stating that existing permits and infrastructure could support a potential return to production in 2028.

The company has stated that it aims to deliver a feasibility study for a silver/antimony mining and refining operation at the Sunshine mine in 2027, which will possibly also include the ability to produce gallium and germanium.

Contact Details
Sunshine Silver Mine Office
Tel +1 208 783 1700
Email info@silveropp.com
Website: https://sunshinesilvermining.com/