The Sunshine Mine mineral deposits are narrow high- grade mesothermal stratbound vein deposits.

The main productive vein systems in the Sunshine Mine include the Sunshine, Chester, Polaris, Copper, Yankee Girl, and West Chance. Mineralized silver veins are present within a zone approximately 12,500 feet long by 5,000 feet wide and extending a vertical distance of 6,200 feet between 3,400 feet above sea level to 2,800 feet below sea level. The mineralization is open at depth below the 5600 Level.

Major veins strike east-west and typically dip 60° to 70° to the south. Vein strike lengths are up to 2,000-plus feet, with the down-dip length two to three times that of strike length and average between one to five feet thick. Mineralized material occurs principally as tetrahedrite and galena with siderite and quartz as the main gangue minerals.

Over 40 veins have been named and mined at the Sunshine Mine. The Sunshine and Chester Veins have each produced over 90 million ounces of silver. The majority of veins strike eastwest and dip about 65° to the south. Locally, dips range from 45° to 90°. Strike lengths locally exceed 2,000 feet and dip lengths are two to three times greater than the strike length. Major veins are located between the faults at an angle of 25° to the bounding faults. Veins vary in width from a few inches to over 30 feet, but are typically between one to five feet thick. Mineralized material includes tetrahedrite and galena with siderite and quartz as the principal gangue minerals. Accessory minerals include bournonite, pyrargyrite, and magnetite.

The silver content of the tetrahedrite varies and the silver-to-copper ratio in the mineralized material ranges from 40:1 (ounce per ton silver:percent copper) up to 100:1. Tetrahedrite occurs as blebs, fracture fillings, or in veinlets. Grades on the veins vary from low-grade material to well over 1,000 opt of silver before mining dilution. Samples of over 2,000 opt of silver have been collected in the mine.

Mineralogy is quite simple in the mineralized materials of the district and at the Sunshine Mine. Typically the Sunshine Mine mineralized material consists principally of tetrahedrite, the high silver-content copper antimony sulfide (3Cu2 S • Sb2 S3). The silver content of the tetrahedrite varies considerably, and the silver-to-copper ratio in the mineralized material ranges from 40:1 (ounce silver per ton: percent copper) to over 100:1. Tetrahedrite occurs as very fine grains in fracture fillings, veinlets, or discontinuous blebs in the vein-filled faults. This silver-bearing tetrahedrite is more properly called freibergite. Freibergite contains 3% to 30% silver substituting for the copper in the crystal structure. Gangue minerals are predominantly siderite (FeCO3) with lesser amounts of quartz (SiO2). Other sulfide minerals principally galena (PbS) and minor associated sphalerite (ZnS), are present in the mine and district veins. Four veins at the Sunshine Mine contain notable galena content including the West Chance, Silver Syndicate, Chester Hook, and the recently discovered 10 Vein. Other metallic minerals seen in the local vein assemblage gangue include pyrite (FeS2), arsenopyrite (FeAsS), boulangerite (5PbS • 2Sb2S3), bournonite (2PbS • Cu2S • Sb2S3), pyrargyrite (3Ag2S • Sb2S3), and magnetite (Fe3O4).

Production mining has been broken into three mining areas. The three mining areas are identified as the Upper Country (above 2300 Level), the Lower Country (below the 2300 Level and above the 4600 Level), and the Bottom Area (below the 4600 Level and above the 5800 Level). The Bottom Area includes 23 stopes on the 4600 Level that were initially omitted from the Lower Country area.

Most of the mineralized material is planned to be hauled to the Jewell Shaft ore loading pockets and hoisted to the surface up the Jewell Shaft. The exception will be material above the 2300 Level, most of which is planned to be hauled up the upper mine ramp system to the surface. Waste material will either be used as backfill or hauled to the Silver Summit Shaft. Some waste may also be hoisted by the Jewell Shaft.

The Jewell Shaft and hoist is planned to be rehabilitated and equipped with new lighter bottom dump skips, raising the hoisting capacity to 1,300 tpd. The mineralized material is planned to be unloaded into the concentrator’s coarse ore bin, while the first 500,000 tons of waste is planned to be placed in the existing WRSF and the remaining waste will be hauled to the ConSil WRSF or hoisted up the Silver Summit Shaft and hauled to the nearby ConSil WRSF. Some waste can be used as backfill in longhole and overhand stopes.

Potential mining methods include underhand and overhand cut and fill mining generally using paste backfill, longhole stoping, and breast-down of exposed mineralized material with minimal vertical extent.

The Sunshine Mine’s processing facility will receive ROM mineralized material, initially from the Upper Country portion of the deposit through the Sterling Tunnel. Later the Lower Country mineralized material will be delivered by an existing hoist in the Jewell Shaft on the Sunshine Mine site. ROM mineralized material will be delivered from the hoist to the ROM ore bin and then fed to the primary crushing circuit. Material from the Sterling Tunnel will be delivered to a truck dump area at an above ground stockpile that will also be fed to the primary crushing circuit.

The processing facility is expected to consist of a comminution circuit followed by a silver and copper flotation circuit and a subsequent lead flotation circuit to produce two concentrates. The two concentrates are planned to be thickened and filtered for load out to bulk containers. Bulk concentrate would be stored onsite for shipment to appropriate metal recovery facilities. The concentrate storage facili ........