The Juneau gold belt is located in the

southeastern The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each se ...

portion of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

. This belt is approximately in length, north/northwest-trending, and extends from

Berners Bay Berners Bay (Lingít: ''Dax̱anáak'' or ''Wóoshde X̱’al.át Yé'') is a waterway in the U.S. state of Alaska, approximately north of Juneau. It is a large and deep indentation, about wide at the entrance, which is formed by Point Bridget and ...

southeastward to

Windham Bay Windham Bay is located southeast of Juneau, in the U.S. state of Alaska. Windham Bay is listed as site 6 within Southeast Alaska's Zone 3 of the Alaska Dept. of Environmental Conservation's Geographic Response Strategy oil spill response pla Part ...

, southeast of

Juneau The City and Borough of Juneau, more commonly known simply as Juneau ( ; tli, Dzánti K'ihéeni ), is the capital city of the state of Alaska. Located in the Gastineau Channel and the Alaskan panhandle, it is a unified municipality and the se ...

, and includes

Douglas Island Douglas Island is a tidal island in the U.S. state of Alaska. It is part of the city and borough of Juneau, just west of downtown Juneau and east of Admiralty Island. It is separated from mainland Juneau by the Gastineau Channel, and contains t ...

. The belt contains over 200 gold-quartz-vein deposits with production nearing of gold. More than three-quarters of Alaska's lode gold was mined from the Juneau gold belt.

History

Gold mining in the belt became active after an 1869 study of the

Juneau mining district The Juneau mining district is a gold mining area in the U.S. state of Alaska. In 1880 a local inhabitant, Chief Kowee, revealed to prospectors Joe Juneau and Richard Harris the presence of gold in what is now named Gold Creek in Silver Bow Basi ...

, of which the Juneau gold belt is but one part. Chief Kowee was one of the earliest gold prospectors in the belt area. In 1880, he revealed to prospectors

Joe Juneau Joe or JOE may refer to: Arts Film and television * ''Joe'' (1970 film), starring Peter Boyle * ''Joe'' (2013 film), starring Nicolas Cage * ''Joe'' (TV series), a British TV series airing from 1966 to 1971 * ''Joe'', a 2002 Canadian animated ...

and

Richard Harris Richard St John Francis Harris (1 October 1930 – 25 October 2002) was an Irish actor and singer. He appeared on stage and in many films, notably as Corrado Zeller in Michelangelo Antonioni's '' Red Desert'', Frank Machin in ''This Sporting ...

the presence of

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

Silver Bow Basin The Silver Bow Basin, often written as Silverbow Basin, is a valley located northeast of Juneau, Alaska, USA. It is situated on Gold Creek in an area north of Icy Gulch, and approximately north of Gastineau Peak. A trail from Juneau leads dire ...

's Gold Creek, after which Juneau was founded in the same year. The Juneau

gold rush A gold rush or gold fever is a discovery of gold—sometimes accompanied by other precious metals and rare-earth minerals—that brings an onrush of miners seeking their fortune. Major gold rushes took place in the 19th century in Australia, New Z ...

of 1880 resulted in some of the largest gold mines in the world, including the Treadwell complex of lode mines on

and the Alaska-Juneau lode mine, in Juneau itself. The steep, wet, timber-covered, seaside mountain setting provided water power, transportation, and lumber such that, "extraordinarily low costs of operation make available low grade ore that under conditions only slightly different would be valueless."Eakin, H.M., p96., Mineral Resources of Alaska, 1914, USGS Bulletin 622 In 1895, southeastern Alaska was the first part of the

Territory of Alaska The Territory of Alaska or Alaska Territory was an organized incorporated territory of the United States from August 24, 1912, until Alaska was granted statehood on January 3, 1959. The territory was previously Russian America, 1784–1867; the ...

to have its mineral resources researched by the

U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...

. It surveyed the gold deposit areas of Juneau and

Sitka russian: Ситка , native_name_lang = tli , settlement_type = Consolidated city-borough , image_skyline = File:Sitka 84 Elev 135.jpg , image_caption = Downtown Sitka in 1984 , image_size ...

. Systematic surveying began in 1902 which included a topographic map of the gold-bearing area adjacent to Juneau. In the following year, a detailed map of the Juneau region's geology was mapped in detail. A reconnaissance of almost the entire Juneau gold belt was carried out from Port Houghton to the boundary with

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

; in 1904, another reconnaissance, this time of nearby

Admiralty Island Admiralty Island is an island in the Alexander Archipelago in Southeast Alaska, at . It is long and wide with an area of , making it the seventh-largest island in the United States and the 132nd largest island in the world. It is one of the ...

, was conducted, concentrating on ore deposits and

economic geology Economic geology is concerned with earth materials that can be used for economic and/or industrial purposes. These materials include precious and base metals, nonmetallic minerals and construction-grade stone. Economic geology is a subdisciplin ...

. The 1986 study by the Bureau of Mines concentrated on the mineral resources of the northern region of southeast Alaska, specifically covering the Juneau gold belt. Aside from information on geological formations of the area, data related to mining was also examined.

Geography

The Juneau gold belt comprises a section of the Juneau Mining District, the other sections being Glacier Bay/Mt. Fairweather, the volcanic area of West Lynn Canal/Haines/Porcupine, and the Molybdenite area. The northern part of the belt, the Eagle River region, extends northwestward from Salmon Creek to

. It is in length. Throughout the inland portion of the belt, outcrops below the timber line are buried under glacial drift, moss, and vegetation. The belt is characterized as a narrow strip of land lying between salt water and the Coast Range's high diorite peaks. It trends northwest and southeast, following the coast.

Gastineau Channel Gastineau Channel (Lingít: ''Séet Ká'') is a channel between the mainland of the U.S. state of Alaska and Douglas Island in the Alexander Archipelago of southeastern Alaska. It separates Juneau on the mainland side from Douglas (now part of J ...

and

Lynn Canal Lynn Canal is an inlet (not an artificial canal) into the mainland of southeast Alaska. Lynn Canal runs about from the inlets of the Chilkat River south to Chatham Strait and Stephens Passage. At over in depth, Lynn Canal is the deepest fjord ...

form the southwest border while Berners Bay forms a northwest one. Between Lynn Canal and the mountains, whose altitude ranges between , there are parallel ridges. The region contains numerous glaciers and several waterways, such as the Montana and Windfall creeks, Windfall Lake at McGinnis Creek, Lemon Creek, Montana Basin, and Auke Lake. The Montana, Windfall, and Cowee creek valleys create a single system along the belt. Larger rivers, like the Eagle, Herbert, and Mendenhall, form gravel valleys following the belt's path.

Geology

The gold belt stretches over a length of trending north-northwest of the Cretaceous Terrance complex. The complex is hosted in an accretionary

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

and

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...

s which have undergone

greenschist Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically and 2–10 kilobars (). Greenschists commonly have an abundance of green minerals such as chlorite ...

grade

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

. Resulting lithologies include:

phyllite Phyllite ( ) is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation.Stephen Marshak ''Essentials of Geology'', 3rd ed. It is primarily compo ...

(some are

graphitic Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

and

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...

(greenstones), along with minor

marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or Dolomite (mineral), dolomite. Marble is typically not Foliation (geology), foliated (layered), although there are exceptions. In geology, the ...

and

quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...

. Gold bearing

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

and

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

fillings of the area are comparable with the California " mother lode" deposits. Most of the gold mines in the Juneau belt occur in the band of black

slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. ...

which lies between the

schists Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...

to the northeast and the greenstones to the southwest. "The complex of veins which follow this black slate is described as the main lode system of the Juneau belt." "Parallelism of vein systems and ore deposits with the outcrops of bed-rock formations...is one of the noteworthy characteristics of the district." This results in a "linear distribution of the mines." Most of the gold deposits are found distributed within associated

sulfide minerals The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ...

and is extracted via free milling.

Pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...

is the most common sulfide found in these deposits followed by

pyrrhotite Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is ...

File:Juneau geologic map.PNG,

Geologic map A geologic map or geological map is a special-purpose map made to show various geological features. Rock units or geologic strata are shown by color or symbols. Bedding planes and structural features such as faults, folds, are shown with st ...

of the Juneau area File:Juneau Gold Belt.PNG, Map of principal mines, marked by an "x", in the Juneau Gold Belt

Flora

Flora includes spruce, hemlock, pine, grassy parks, cedar, blueberry brush, devil's club, alder, and hemlock.

References

{{Reflist Juneau, Alaska Gold mining in Alaska Geology of Alaska Belt regions of the United States

History

Geography

Geology

Flora

See also

References