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The Sunshine Mine is located between the cities of Kellogg and Wallace in northern Idaho. It has been one of the world's largest silver mines, having produced over 360 million ounces of silver since 2001.
A 2007 Canadian report by Behre Dolbear & Company estimated measured and indicated resources of 31.51 million ounces of silver in 1.43 million tons at 21.8 ounces of silver per ton and inferred resources of 231.5 million ounces of silver in 2.28 million tons at 101.6 ounces of silver per ton. The Behre Dolbear report is considered historic in nature and illustrates the resource potential of the Sunshine Mine.
The Sunshine Mine property had its beginning in 1884 when the Blake brothers staked the Yankee Lode mining claim. Various contiguous holdings were consolidated to become the Sunshine Mining Company in 1920. The mine was then an economically marginal property consisting of 15 patented claims and one unpatented claim, shipping hand-sorted ore with a silver price of a dollar per ounce. In 1921 a 25-ton per day mill was constructed. The mill was later expanded piecemeal and eventually reached a daily capacity of 500 tons. Soon after the concentrator was commissioned, the Sunshine tunnel was driven from the surface in an exploration effort which discovered higher quality ore historically identified as "Chinatown"
In 1926, encouraged by the production success in the Chinatown area, upper Sunshine vein, the Incline shaft was sunk from the Sunshine tunnel to well below the bottom of the Chinatown working areas, eventually reaching the 1900 level in 1934. Soon after, drift crews discovered a bonanza vein of the first order. The No. 3 shaft was then started, eventually reaching the 3100 level in 1938.
In 1935 the concentrator was upgraded with new ball mill grinding units and flotation cells increasing the capacity to 1,000 tons per day while attaining a recovery of 98%. The sinking of the new four-compartment vertical Jewell shaft was started, reaching the 2300 level in 1936.
In 1943 a crew drifting east on the 2700 level following the Silver Syndicate fault discovered the famous Chester vein.
It was primarily the exploitation of the Sunshine vein followed by the Chester vein that determined the present configuration of the underground workings. With the discovery of the Chester vein on the 2700 level and the ore body's distance from the Jewell shaft of approximately 4000 feet east - southeast, other internal shafts (the No. 4, No. 5 and No. 10 shafts, more properly defined as winzes) were sunk or raised to more efficiently service the operations. The other principal internal shaft is the No. 12 shaft, servicing the Copper vein and the West Syndicate vein in the western end of the mine.
In 1960, sand-filling operations were introduced underground. The mill tailings were classified so that the coarser material, approximately 45% of the total mill feed, was used for stope backfill.
In the morning of May 2, 1972, a fire broke out in the Sunshine Mine. According to the US Mine Rescue Association, 91 workers died from smoke inhalation or carbon monoxide poisoning; 83 men were rescued, 81 on May 2 and two on May 9. The mine was closed for seven months after the fire, which was one of the worst mining disasters in American history and is the worst disaster in Idaho's history. Today, a monument to the lost miners stands beside Interstate 90 near the mine.
By the end of 1988, the mine was at full production. Ore production was primarily from mining the Chester vein systems serviced by the No. 10 shaft and the remnants of the Sunshine and Rambo vein stopes referred to as the Footwall area on the 3700 and 3400 levels. The 4000 and 4200 level Copper vein was under development from the No. 12 shaft.
In 1989, the mine produced 4.8 million ounces of silver. Production from the high grade Copper vein stopes began to impact the silver production volumes. During 1990, the mine produced 5.4 million ounces of silver, the most since 1971. By now the high-grade Copper vein stopes on 4200 level were becoming substantial producers, while production from the 10 shaft stopes was dropping off.
In 1991 the silver price fell to $3.90 per ounce and the operation was losing money. A mining plan was put together to reduce losses substantially while waiting for prices to improve. This was referred to as the "small mine plan" and was implemented in June 1991. The operation headings underground were centralized by shutting down the outlying, more costly production and development headings, and limiting operation to day shift only. The mining operations were consolidated in the Copper vein area and the most productive headings in the "Footwall Area". The mine below the 5000 level was salvaged and allowed to fill with water. Production was cut in half, while the work force was reduced by 65%.
The West Chance vein was discovered in 1992. By late 1996 it was clear the ore body was of sufficient size and value to support the mine's return to full production. The reserves were then developed by trackless ramp and lateral development methods using LHD (Load-Haul-Dump) equipment. The working areas outside the West Chance were shut down and salvaged in an orderly fashion and all resources were directed toward the West Chance. By July 1997, the mine workings below the 4000 level were salvaged of all usable equipment and materials and allowed to begin filling with water. In 1995, Sunshine acquired the neighboring Consolidated Silver (ConSil) property consisting of the surface facilities and underground workings of the Silver Summit Mine. This mine has served as the Sunshine Mine's second access for years. The ConSil underground mine workings are primarily accessed by an adit to an internal 5600 feet shaft. The surface opening of this adit is located about two miles east of the Jewell shaft.
The mine ceased production in the first quarter of 2001 because of several factors. These included low silver prices and the lack of regular and consistent exploration and development due to prior management shifting cash flow from the mine to corporate expenses, debt and other projects.
At closure the mine reserves were 1.13 million tons containing 26.75 million ounces of silver at 23.6 ounces Ag/ton. Upon closing of the mine these 'Historic' or 'Legacy reserves' were reclassified to 'mineralized material' as required by United States Securities and Exchange Commission regulations. These "Legacy Resources" are now classified as Mineral Resources under the CIM Definition Standards.
From historical records beginning in 1904 the Sunshine Mine has produced 364,893,421 ounces of silver from 12,953,045 tons of ore through 2001 when the mine was closed. From January 1, 1998 to January 1, 2004 the average reserves carried by the mine were 1.38 million tons containing 32.20 million ounces of silver at 23.3 oz Ag/ton.
On November 2, 2009, Alberta Star Development Corp. announced that it has entered into a binding term sheet with Sterling Mining Company to acquire a controlling interest in Sterling and its assets and provide for financing of Sterling's ongoing operations. Alberta Star later gave up their pursuit of the mine in the face of competing interest.
On April 22, 2010, Sterling Mining Company announced that Court papers will be filed shortly seeking to approve a successful $24.0 million bid for the assets and stock of Sterling Mining Company, the operator of the historic Sunshine Mine. The successful bidder—with a cash price of $24.0 million—was Silver Opportunity Partners LLC (SOP). SOP is a privately held company owned by Thomas Kaplan. It is based in New York as part of the Electrum Group of Companies, an international investor in precious metal mines.
On February 14, 2012, the mine was evacuated after a sensor in a vent shaft detected elevated levels of carbon monoxide inside. Twelve people were underground at the time, during the evening. All were workers for an underground mining services contractor called The Redpath Group, with headquarters in North Bay, Ontario, Canada. The mine was evacuated and sealed. All intakes feeding oxygen into the mine had to be sealed off, and nitrogen was injected to further reduce oxygen levels and extinguish the fire. On June 12, 2012, working under the guidance of the federal Mine Safety and Health Administration (MSHA) the seal was broken on the shaft and crews reached the mine's 3,100-foot level where the fire started. Gas readings at the 3,100 level showed no carbon monoxide and appropriate levels of oxygen, indicating the fire was out.
The district is hosted by rocks of the Pre-Cambrian Belt super group, which is divided into the Prichard group, Ravalli group, Middle Carbonate group, and Missoula group. The Ravalli group contains the Revette and St. Regis formations that are the preferred host rocks for silver mineralization in the district. Ore deposits are localized within the 600 ft. thick St. Regis formation and the underlying upper members of the 3,000 ft thick Revette formation. The contact between the formations is indistinct and is locally picked as being the bottom of the lower-most distinct purple-colored interval in the St. Regis. Rock types include argillite, siltite, sericitic quartzite, and vitreous quartzite.
The Sunshine Mine infrastructure is antiquated and will require repairs and renovations. Water and electric supplies are sufficient for near-term future use. Property access is by a 2 mile paved county road paralleling Big Creek that intersects US Interstate 90. Communications, including telephone are installed and operable.
Over 30 veins have been named and mined at the Sunshine Mine. While the initial work suggested distinct veins, some of these veins are actually offsets across post-ore structures and others represent parallel footwall or hanging wall veins. Principle vein systems in the mine include the Sunshine, Chester, Copper, Yankee girl and West Chance. The Sunshine and Chester veins have each produced over 100 million ounces of silver. Major veins strike east-west and dip about 65° to the south. Locally, dips range from 45° to 90°. Strike lengths exceed 2000 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 about 25° to the bounding faults. Veins vary in width from a few inches to over 30 feet, but are generally 1 to 5 feet thick. Ore minerals include tetrahedrite and galena with siderite and quartz as the principal gangue minerals. The silver content of the tetrahedrite varies and the silver to copper ratio in the ore ranges from 40:1 (opt Ag:%Cu) to over 100:1. Tetrahedrite occurs as blebs, fracture fillings, or in veinlets. Samples exceeding 200 oz/ton silver have been collected in the mine. Other minerals include pyrite and arsenopyrite with minor to trace amounts of chalcopyrite, sphalerite, boulangerite, bourmonite, pyrargyrite, and magnetite.
Notes and References
- Brock, James (1995). The Sunshine Mine Disaster. University of Idaho Press. ISBN 0-89301-181-9.
- Olsen, Gregg (2005). The Deep Dark: Disaster and Redemption in America's Richest Silver Mine. New York: Crown Publishers. ISBN 0-609-61016-3.
- Behre Dolbear, NI43-101 report, New York, [vague]
- "Idaho's Silver Valley Poised for Expansion". Mining (January 2011): 8.
||This section's use of external links may not follow Wikipedia's policies or guidelines. (March 2012)|
- Boise State University, Albertsons Library
- Comprehensive list of resources including books, government documents, websites and search tips
- Mining Disaster: An Exhibition. 1972 Sunshine Mining Company Mining Disaster Kellogg, Idaho
- Published by U.S. Department of Labor, Mine Safety and Health Administration. Includes photographs of the Sunshine Mine site as the events of that day are retold.
- Outdoor Idaho's Silver Valley Rising Idaho Public Television, includes interviews and text
- Sunshine Mine Fire: A view from the inside. United States Mine Rescue Association
- Sunshine Mine Memorial (photos & information):
- The Sunshine Mine accident and its aftermath, from the United States Mine Rescue Association (USMRA) website
- The Sunshine Mine Fire Disaster: A View From The Inside, another description, also from the USMRA website
- The Sunshine Mine Disaster, a home page by the author of the 1995 book, via a Florida Gulf Coast University website
- Survivors discuss Sunshine Mine fire, a March 2005 interview of the author of the 2005 book, from the Bellingham Herald website
- Underground In The Sunshine, a reprint on an ad-supported personal website of a short story about working in the Sunshine Mine in 1946, first published in the International California Mining Journal in October 1998
- Sterling Mining Company official website[dead link]
- Frank Starr's 45 rpm recording of Tragedy At The Sunshine Mine
- Sterling Mining Company Announces Successful Auction of Stock and Assets
- Mine owner has big plans
- About Kellogg, ID
- Kellogg Redefined: A Mining Town Reinvents Itself by Prof. Harley Johansen, University of Idaho Spring 2006
- Western Mining History.com Kellogg, Idaho
- Coeur d'Alene Mining District[dead link], about Kellogg and the Silver Valley, from the Idaho Public Television website
- Kellogg's history and a list of events there, from a personal website
- Tarnished Luster, a reprint on the author's website of an article on Kellogg and the Silver Valley published in the Smithsonian in October 2001