Greens Creek Mine, Hawk Inlet

Greens Creek Mine, Hawk Inlet

by | Aug 19, 2021

Greens Creek Mine is the 5th largest silver producer in the world, located on the eastern shore of Hawk Inlet on Admiralty Island, about 77 miles (124 km) north-northeast of Sitka and 18 miles (29 km) southwest of Juneau, Alaska. Admiralty Island is 96 miles (155 km) long and lies between Stephens Passage to the east and Chatham Strait to the west. The Tlingit people call the island Xootsnoowú, which is commonly interpreted as Fortress of the Bears. The island was named in 1794 by Captain George Vancouver for the British Admiralty. The Captain Mikhail Tebenkov of the Imperial Russian Navy published the name Ostrov Kutsnoi, reputedly meaning “fear island”. Most of Admiralty Island is within the Admiralty Island National Monument, a federally protected wilderness area administered by the Tongass National Forest. The Kootznoowoo Wilderness encompasses most of the island except for the Mansfield Peninsula and is known for vast stands of old-growth temperate rainforest, and home for the highest density of brown bears in North America. Hawk Inlet is located on the northern end of Admiralty Island and is about 7 miles (11 km) long and nearly bisects the island from the Mansfield Peninsula. The inlet was used by the Tlingit for thousands of years as a shortcut between Chatham Strait and Stephens Passage. Post-glacial rebound of the land has now closed the waterway with a tidal mudflat and marsh about 0.9 miles (1.5 km) wide that was historically used as a canoe drag or portage. The Tlingit name for the inlet is Weinedel meaning Eelgrass Where Herring Spawn. In 1910, a salmon cannery was built on Hawk Inlet by Hawk Inlet Fish Company. This was sold to P.E. Harris Company in 1914, which changed its name to Peter Pan Seafoods in 1962, and the cannery operated until it burned in 1976.

A belt of metamorphic rock containing large well-defined quartz fissure veins extends from Funter Bay to Hawk Inlet. This was extensively prospected before 1900 by Admiralty Alaska and Alaska Dano companies from Funter Bay and by Charles Williams and others from Hawk Inlet. The Alaska Empire Mine on the west shore of Hawk Inlet operated between 1911 and 1946. The mine workings included a glory hole that from 1931 to 1937, produced 17,767 tons of gold-bearing ore. The deposits on the east shore of Hawk Inlet at Greens Creek were discovered in 1975 about 9 miles (15 km) south of Hawk Inlet. Mining began in 1989 targeting zinc, lead, silver, and gold. Mining was suspended in April 1993 due to low metal prices and resumed in 1996 at full capacity. The mine is primarily an underground operation. Filter pressed mine tailings from the milling process are backfilled in the mine and also deposited at surface tailings piles. The mill produces semi-pure Doré bars of silver, gold, zinc, and lead on-site. These are trucked from the mill complex to a port site on Hawk Inlet for export to smelting and refining facilities. The port includes support facilities for the mining and milling operation including concentrate storage, vessel docking, shift housing, and a domestic wastewater treatment plant.

Greens Creek Mine uses a floatation process to concentrate the ore which involves the addition of compounds such as copper sulfate, diesel fuel, and sodium cyanide to the ore before separation of the valuable components. The residue or mine tailings are then thickened with concrete and disposed of, either as backfill in the mine or at dry tailings disposal sites. These disposal sites originally covered 29 acres (12 ha), but in 2004 the mine received approval from the U.S. Forest Service to expand this to 85 acres (34 ha). As a result, concerns about toxic waste entering Hawk Inlet initiated a monitoring program to document the water quality, sediment chemistry, and biological accumulation in receiving waters that may be impacted by the mine’s operations. In 1995, the Greens Creek Mining Company entered a 99-year land lease with the U.S. Forest Service to conduct additional mineral exploration, development, and production, with an option of continuing to expand the mine until the year 2094. Historically, the mine used diesel generators to supply power, but now a submarine cable transmits 95 percent of the power directly from the Juneau electricity grid. The mine is the largest private employer in the Juneau area with 280 workers. Most mine workers commute from Juneau on a high-speed ferry that operates from a dock on Youngs Bay in Stephens Passage that is connected to the port facility by 4 miles (6 km) of road. Read more here and here. Explore more of the Greens Creek Mine and Hawk Inlet here:

About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2022 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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