Sunshine Mine and mill, Evolution Mining District, Shoshone County, Idaho, USAi

Regional Level Types
Sunshine Mine and mill	Mine
Evolution Mining District	Mining District
Shoshone County	County
Idaho	State
USA	Country

Located in the Big Creek valley, a tributary of South Fork Coeur d'Alene River approximately 3 miles (4.8 kilometers) southeast of Kellogg, Idaho.

Commodities (Production): antimony, copper (50,000,001-75,000,000 lbs), gold (5,001-10,000 oz), lead (75,000,001-100,000,000 lbs), silver (200,000,001-250,000,000 oz), zinc (6,000,001-8,000,000 lbs).
Development Status: Past Producer
Host Rock Unit(s): Wallace Formation; Revett Formation, St. Regis Formation
Host Rock(s): Quartzite
Structure(s): Polaris Fault, Chester Fault, Silver Syndicate Fault, Big Creek Anticline, Chance Fault
Alteration(s): Oxidation, Sericitization, zeolite facies metamorphism
Deposit Type(s): Veins (pinch and swell and tabular)
Tectonic Structure: Belt Basin.

The US Geological Survey report (MRDS 10241626) contains the following comments about the deposit:
"Veins typically consists of a core of massive ore, bounded by selvages of quartz, then pyrite veinlets in siderite-ankerite, and then passing into altered (bleached with sporadic sericitization) wall rock. Contact with wall-rock is sharp, often marked by a thin seam of sericite gouge. Massive ore consists of siderite-quartz-ankerite (rarely -barite) gangue with disseminated sulfides of tetrahedrite, galena, chalcopyrite, arsenopyrite, sphalerite, pyrite, boulangerite, bournonite, and gersdorffite.

Upper part of the Sunshine vein was at least partly oxidized with some degree of sulfide enrichment. In the oxide zone, azurite, malachite, cerargyrite, native silver, anglesite, cerussite, and erythrite have been reported. Enriched sulfides include covellite, chalcocite, acanthite, and pyrargyrite (sometimes misidentified as proustite).

Envelopes of disseminated arsenopyrite occur around the veins, and are probably associated with more extensive halos of disseminated carbonates."

MRDS 10241626 also contains the following comments on the orebody:

"The Sunshine and Polaris veins are parallel veins, the Sunshine in the hanging wall and Polaris in the foot wall of a shear zone, which coverge at about the 1300 foot level (396 meters). At depth the vein system consists of several branching and parallel veins, including the 'B', 'D', and '06' veins. At the east end of the vein system, three main veins were mine known as the North, South, and Middle Polaris veins. Above the 1500 (457 meter) level, quartz is more abundant and some galena is present; below the 1500 level the vein is rich in tetrahedrite. The vein passes into Revett Formation quartzite at the 3700 (1128 meter) level. The vein terminates to the east at the Silver Syndicate Fault. The ore contains from 1700 to 2600 grams per ton silver per percent of copper.

The Chester Vein System branches off the Silver Syndicate Fault via the North Hook (Chester Hook) and then follows the Chester Fault for 2,377 meters. This is a replacement vein except for tension gash-filling in the North Hook area. Upper levels of the vein are mixed galena-tetrahedrite ores, but the proportion of tetrahedrite increases with depth until the 3700 level (1128 meters) is reached below which galena is absent. Highest grades are at the 5000 (1524 meters) level and below. The ore contains 2600 grams per ton silver per percent copper.

The Silver Syndicate replacement vein lies entirely in the Silver Syndicate Fault. Three major ore shoots were mined from the surface down to the 4000 (1219 meter) level. Little ore was found from the 3850 (1173 meter) to the 4000 level. The vein consisted of quartz, siderite, pyrite, and galena (which contains remnants of tetrahedrite).

The Yankee Girl vein is a hanging-wall split from the Sunshine-Polaris shear zone that occupies a shattered zone in the north limb of the Big Creek Anticline. Narrow, interlacing massive siderite-tetrahedrite veins and veinlets formed several ore zones 1 to 2 meters wide, none of which were mined below the 3700 (1128 meters) level. Veins contain siderite, ankerite, quartz, pyrite, tetrahedrite, chalcopyrite, magnetite, and hematite. Ore contains 1400 grams per ton silver per percent of copper.

Uraninite mineralization occurs in the footwall of the Sunshine-Polaris vein system from the 2900 (884 meters) to 3700 (1128 meters) levels in St. Regis Formation quartzite. Mineralization consists of quart-pyrite-uraninite veins and veinlets with selvages of dissemintad hematite."

MRDS 10241626 contains the following comments on the ore emplacement controls:

"Ore is hosted by E-W trending, steeply S dipping replacement veins within shear zones parallel to bedding on the north limb of the overturned Big Creek Anticline. Clean quartzite from the Revett Formation and the Revett-St. Regis Transition Zone are the best host rocks for ore. Less ore is found in sericitic quartzite in the Wallace and St. Regis Formations. Veins flatten out (refract) when they pass from argillite into quartzite.

Vein intersections plunge steeply southwest, near the dip line and parallel to synmineral mulltions, grooving, rodding, and slickensides. Veins were formed during inhomogenous ductile shear with slip in a field of uniaxial stress parallel to the line defined by fracture/vein intersections. Ore shoots are elongate in, and controlled by, this slip plane."

MRDS 10241626 contains the following comments on the geology:

"Isotopic studies (Eaton and others, 1995) indicate that contemporaneous deformation, metamorphism, and mineralization occurred during the Late Cretaceous to Early Tertiary, probably due to the emplacement of the Idaho Batholith south of the Coeur d'Alene Mining region.

Wallace Formation calcareous argilite and quartzite amd St. Regis Formation argilite and quartzite exposed at surface. Revett Formation quartzite exposed only on the 3100 level of the Sunshine mine an below.

At the Sunshine mine, the Wallace Formation is 1200 to 1500 meters thick, the St. Regis Formation 500 to 600 meters thick, and the Revett Formation 650 to 1050 meters thick."

MRDS 10241626 contains the following comments on the mine workings and development:

"More than 100 miles (161 kilometers) of underground workings when the mine closed in 2001.

The modern Sunshine mine is a consolidation of many properties, totaling 930 hectares, and including the Yankee Boy Group of 5 patented claims, the Yankee Girl Group of 11 patented claims, the Majestic Group of 2 unpatented claims, and many others.

Initial mining method in the 1920s was rill stoping, shortly replaced by square set with development rock fill. Horizontal cut and fill with occasional shrinkage stoping was adopted later, with tailings fill used from 1960.

In 1943, bonanza silver ore was discovered on a deep extension of the Chester Vein into the St. Regis Formation."

Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Sunshine_Mine
Wikidata ID:	Q7641530
Link to USGS MRDS:	10241626

Other Regions, Features and Areas containing this locality

References