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samedi 9 avril 2011
Historical lode of Gold
Southeast Alaska
Porcupine district
Over 81,000 ounces of placer gold came from the Porcupine district near Haines. Porcupine Creek, about 20 miles (32 km ) north of Haines, is the site of a 1898 gold discovery; the creek has been intermittently placer mined ever since. Outside of the Porcupine basin only a few other creeks - Glacier, Nugget and Cottonwood - produced significant gold. The area around Reid Inlet, in modern Glacier Bay National Park and Preserve, hosted several hard rock gold prospects, including the LeRoy mine, which exploited quartz veins for about 10,000 ounces of gold production. The district, which includes Skagway and Haines, is bordered to the north and east by Canada . To the west is the Pacific Ocean and the Chichagof District lies to the south. The Discovery Channel series Gold Rush Alaska takes place in this region.
Main article: Juneau mining district

Over 7 million ounces of lode gold and 80,000 ounces of placer gold have been recovered from the Juneau district
Admiralty district
Most of the gold recovered from the Admiralty mining district (which consists of Admiralty Island ) is a by product of silver and base metal mining. The Alaska Empire underground lode mine recovered gold from quartz veins in metamorphic rocks. Discovered and staked in the 1920s, production of about 20,000 tonnes of 0.25 ounce-per-ton gold ore occurred in the mid-1930s. The Funter Bay underground lode mine produced about 500 thousand tonnes of copper-nickel-cobalt ore, without gold, from a Mesozoic gabbro-norite pipe. No significant placer mining was done on Admiralty. About 500,000 ounces of gold, almost all from the currently-operating Greens Creek lode silver mine, have been recovered from the Admiralty district.
Approximately 800,000 ounces of gold have come from the Chichagof district. Chichagof, Yakobi, Baranof and smaller islands comprise the district.Numerous lode and placer prospects and mines exist in the district. Major production came from underground lode mines exploiting gold-in-quartz veins.
Apex-El Nido mine
The Apex-El Nido produced perhaps 50,000 ounces of gold from a mile of underground workings exploiting polymetallic quartz veins
From 1922 to 1933 the Hirst-Chichagof produced 133,000 ounces of gold and 33,000 ounces of silver from polymetallic quartz veins assaying nearly 1 ounce of gold per ton. There are over a mile of underground workings, reaching 2,000 feet (610 m ) below the surface. Significant reserves remain, which have attracted exploration efforts in the 1980s and 1990s.
Chichagof mine
The Chichagof mine opened in 1905 and by 1942 had yielded 660,000 ounces of gold and 195,000 ounces of silver from quartz veins assaying over 1 oz gold per ton. There were several miles of workings on 5 levels. Six shafts reached a maximum of 2,750 feet (840 m ) below sea level. Between 1981 and 1988 several thousand feet of new workings were dug, and engineering and environmental studies were done, but the project was abandoned
Petersburg-Sumdum district
Ketchikan district
Approximately 58,000 ounces of lode gold and 4000 ounces of placer gold have come from the Ketchikan district, consisting of Dall, Prince of Wales, Revillagigedo, and smaller islands, as well some mainland, in the southernmost-part of Alaska.[13] Numerous historical lode mines and prospects for base metals, uranium, rare earth elements (REE's), iron, and platinum group elements (PGE's), as well as gold exist in the Ketchikan district. Major gold production came from underground lode mines exploiting: gold-bearing quartz veins in metamorphic rocks (such as the Gold Standard, Sea Level, Dawson , Golden Fleece, and Goldstream mines); skarns (at the Jumbo and Kassan Peninsula copper-gold mines); zoned mafic-ultramafic plutons, as at the Salt Chuck silver-gold-copper-PGE mine; and VMS deposits such as Niblack.
A high-yielding mine in Ketchikan District is the Golden Fleece Mine, located about 0.2 mile north of the north end of James Lake on Prince of Wales Island, latitude: 55.152179, longitude: -132.056635. The mine was most active from 1901 to 1905
Koyukuk-Nolan district
The district encompasses the upper Koyukuk River basin including the Alatna and Kanuti rivers and the village of Bettles . The district extends from the southern flank of the Brooks Range to the northern Ray Mountains, and is directly west of the Chandalar district. Much of the district is now in Gates of the Arctic National Park. Gold was discovered in placer deposits in the district in 1901. About 350,000 ounces of placer gold have been won from the area, perhaps 85% of it from nearWiseman. Mining continues today in the district. Much of the district is underlain by bedded Paleozoic rocks, a schist belt extends along the southern foothills of the Brooks Range . Cretaceous plutons intrude metamorphic rocks in the southern part of the district. Pleistocene ice sheets from the Brooks Range and cirque glaciers in the Ray Mountains covered much of the higher elevations. Glaciers are now restricted to the highest cirques of the Brooks Range .
Miners produced 135,000 ounces of gold from Nolan Creek between 1904 and 1999. Some of the placer gold is mined by underground methods in frozen gravels. A 42-troy ounce nugget, Alaska 's twentieth-largest, came from Marys Bench on Nolan Creek . Placer mining activity continues, with a reserve of 114,760 ounces of gold reported in 2000.
Mining occurred on the Hammond River , a tributary of the Koyukuk River , from about 1900 to at least 2000. Exact production is unknown, it is estimated at about 80,000 ounces .


In 1914,on No. 4 Above, Hammond River (Goldbottom Gulch), J. C. Kinney and partners picked up nuggets from bedrock valued at about $20,000; one nugget, the second largest ever found in Alaska , was worth $2600. The rest of the dump when sluiced yielded a little less than the value of the "pickings." (Engineering and Mining Journal, 1914, p. 1062 Vol. 98 No. 24. (Gold at $20.00 per ounce.)
Placers on Slisco bench, an ancient buried channel of Hammond River near Vermont Creek on the west side of the present Hammond River contain a measured resource of 31,099 oz gold with grades of up to 0.3 oz/cy. Inferred resources on the same bench range from 50,000 to 150,000 oz . (2002) . Other benches of Hammond River between Discovery Claim and Slisco Bench have similar potential but have not been systematically prospected with modern technology.
Maddren USGS Bulletin 532 1913
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