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It Mine (Reed Mine), Kasaan Peninsula, Prince of Wales Island, Ketchikan District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA

Latitude: 55°34'40"N
Longitude: 132°27'54"W
The patented claims of the It Mine were purchased by the Sealaska Corporation in 1998.
Location: The It Mine is located by name on the USGS 1:63,360-scale topographic map; it is about 0.3 mile south of the center of section 36, T. 72 S., R. 84 E. The geology and workings of the It Mine are shown on Plates 23 and 24 of Warner and others (1961).
Geology: The metamorphic rocks at the It Mine consist of thick, northwest-trending, bands and lenses of garnet-epidote-quartz-calcite-pyroxene skarn, marble, and greenstone (Warner and others, 1961; Myers, 1985). They have been intruded by a northwest-trending, irregular band of diorite up to about 700 feet wide, and by several basalt, andesite, diabase, and gabbro dikes. The best ore in the main workings--most of which is mined out--was localized along the contact of skarn and lenses of marble; individual ore shoots have been mined to a depth of about 350 feet. Similar but less extensive ore occurs at the north workings. The ore minerals are mainly pyrite and chalcopyrite. Magnetite is sparse in the mine workings although several small magnetite bodies were found nearby. In his detailed study of the mine, Myers (1985) noted that the skarns are dominated by the association garnet-epidote-quartz-calcite with minor magnetite after platy hematite. The ore has relatively high silver values--greater than 200 parts per million (ppm)--and gold values of less than 10 ppm. The mine has two groups of workings. The main workings consist of two glory holes, 3 adits, several open cuts, and a few trenches. The north workings, about a quarter of a mile northwest of the main workings, consist of a glory hole, two adits, and numerous pits and trenches. The detailed geology of the mine and locations of the numerous workings are shown on plate 23 of Warner and others (1961) and in Myers (1985). Development began in 1907 and the first shipment of copper ore was in 1908. Except for two years, the mine produced steadily until 1918, principally by Granby Consolidated Mining, Smelting, and Power Company. About $1,000,000 in copper was produced. Maas and others (1995) give the total production as 2,030 tons of copper, 28,970 ounces of silver, and 4,372 ounces of gold. The average grade of the ore was 3.99 percent copper, 0.0685 ounce of gold per ton, and 0.478 ounce of silver per ton. Granby reportedly mined out the deposit and was unsuccessful in finding any additional ore bodies in spite of extensive diamond drilling. The Reed prospect nearby is similar (Wright, 1909) and may be part of this mine or the nearby Alarm (CR055) Mine. The It Mine is one of many copper-iron deposits on the Kasaan Peninsula having similar geology and origin (Warner and others, 1961; Eberlein and others, 1983; Brew, 1996). The rocks on the peninsula consist mainly of andesite ('greenstone' in much of the older literature) interbedded with about 25 percent sedimentary rocks comprising approximately equal amounts of limestone or marble, calcareous mudstone and sandstone, and graywacke and conglomerate. These units are part of the Luck Creek Breccia of Silurian and Devonian age, but many of the sedimentary units are similar to and probably grade into rocks of the Silurian and Ordovician, Descon Formation. The bedded rocks are intruded by a profusion of Silurian or Ordovician dikes, sills, and irregular masses of porphyritic gabbro, basalt, andesite, diorite, dacite, and granodiorite. Near some of the deposits, these intrusions may make up 20 percent or more of the outcrop and usually are associated with the development of tactite and alteration of the greenstone. The area subsequently was intruded by several large Silurian or Ordovician plutons; they are mainly granodiorite but locally are diorite and gabbro. The ore deposits are typically small and of irregular shape; often the ore bodies form lenses or mantos. Some of the deposits conform to the layering in the greenstone and sedimentary rocks. The principal ore minerals are chalcopyrite, pyrite, and magnetite; hematite is often present and a little molybdenite occurs in some deposits. Most of the deposits are associated with tactite or skarn with varying amounts of actinolite, calcite, chlorite, garnet, diopside, epidote, and hornblende. There was significant by-product silver and gold in the ore that was mined in the past, and the gold values in some deposits are high enough to have encouraged exploration in recent years. Marble is more common in the deposits in the western part of the peninsula, where the gold values are generally higher as well (Wright and Wright, 1908; Wright, 1915; Warner and others, 1961; Myers, 1985; Bond, 1993; Maas and others, 1995). Early interpretations of the ore deposits on the Kasaan Peninsula emphasize their contact metamorphic origin and their probable Mesozoic age (for example, Warner and others, 1961). However, recent radiometric dating and mapping indicate that the deposits formed in a Silurian or Ordovician, arc-related environment characterized by deposition of andesite and submarine sedimentary rocks that were intruded by swarms of dikes of varying composition, mineralized, and then intruded by large granodiorite plutons (Hedderly-Smith, 1999 [Inventory]). The copper deposits of the Kasaan Peninsula were known to the Russians and the first claim was staked in 1867. Most of the production and development occurred from about 1900 to 1918, especially from 1905 to 1907, when copper prices soared and a smelter was built at Hadley on the north side of the Kasaan Peninsula. After World War I, copper supply exceeded demand, prices fell, and there has been no further copper production since 1918 (Wright, 1915; Warner and others, 1961; Roppel, 1991; Maas and others, 1995). However, because of the intense and widespread mineralization on the peninsula, the area has repeatedly been re-examined for copper, iron, and gold, notably during WW II (Warner and others, 1961) and in the last several decades.
Workings: The mine has two groups of workings. The main workings consist of two glory holes, 3 adits, several open cuts, and a few trenches. The north workings, about a quarter of a mile northwest of the main workings, consist of a glory hole, two adits, and numerous pits and trenches. The detailed geology of the mine and locations of the numerous workings are shown on plate 23 of Warner and others (1961) and in Myers (1985). Development began in 1907 and the first shipment of copper ore was in 1908. Except for two years, the mine produced steadily until 1918, principally by Granby Consolidated Mining, Smelting, and Power Company.
Age: The deposit formed in a Silurian or Ordovician, submarine arc-related environment characterized by the deposition of volcanic and sedimentary rocks, the intrusion of swarms of dikes of diverse composition, and the emplacement of several large plutons.
Alteration: Development of calc-silicate skarn.
Production: About $1,000,000 in copper was produced. Maas and others (1995) give the total production as 2,030 tons of copper, 28,970 ounces of silver, and 4,372 ounces of gold.
Reserves: Probably none left. Granby Mining, Smelting, and Power Company reportedly mined out the deposit by 1919 and was unsuccessful in finding any additional ore bodies despite extensive diamond drilling.

Commodities (Major) - Ag, Au, Cu
Development Status: Yes; medium
Deposit Model: Cu-Fe skarn (Cox and Singer, 1986; model 18d).

Mineral List

Calcite
Chalcopyrite
Epidote
'Garnet'
Magnetite
'Pyroxene Group'
Quartz


7 entries listed. 5 valid minerals.

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References

Bond, R.W., 1993; The mineralogy and geochemistry of the Kasaan Peninsula, iron-copper-silver-gold skarns, Prince of Wales Island, southeastern Alaska: Salt Lake City, University of Utah, M.Sc. thesis, 130 p. Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000. Brooks, A.H., 1910, Mineral resources of Alaska, report on progress of investigations in 1909: U.S. Geological Survey Bulletin 442, 426 p. Brooks, A.H., 1912, The mining industry in 1911, in Brooks, A.H., and others, Mineral resources of Alaska, report on progress of investigations in 1911: U.S. Geological Survey Bulletin 520-A, p. 17-44. Brooks, A.H., 1913, The mining industry in 1912: U.S. Geological Survey Bulletin 542-A, p. 18-51. Brooks, A.H., 1915, Mineral resources of Alaska; report on progress of investigations in 1914: U.S. Geological Survey Bulletin 622, 380 p. Brooks, A.H., 1921, The future of Alaska mining, in Martin, G.C., and others, Mineral resources of Alaska, 1917: U.S. Geological Survey Bulletin 714-A, p. 5-57. Buddington, A.F., and Chapin, Theodore, 1929, Geology and mineral deposits of southeastern Alaska: U.S. Geological Survey Bulletin 800, 398 p. Bufvers, John, 1967, History of mines and prospects, Ketchikan district, prior to 1952: Alaska Division of Mines and Minerals Special Report 1, 32 p. Chapin, Theodore, 1916, Mining developments in southeastern Alaska: U.S. Geological Survey Bulletin 642-B, p. 73-104. Chapin, Theodore, 1918, Mining developments in the Ketchikan and Wrangell mining districts: U.S. Geological Survey Bulletin 662-B, p. 63-75. Chapin, Theodore, 1919, A molybdenite lode on Healy River: U.S. Geological Survey Bulletin 692, p. 329. Cobb, E. H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-869, 262 p. Eberlein, G.D., Churkin, Michael, Jr., Carter, Claire, Berg, H.C., and Ovenshine, A. T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-91, 52 p. Hedderly-Smith, D.A., 1999, Inventory of metallic mineral prospects, showings and anomalies on Sealaska lands, 1988 through 1998: Sealaska Corporation, Juneau, Alaska, 217 p. (internal report held by Sealaska Corporation, Juneau, Alaska). Knopf, Adolph, 1910, Mining in southeastern Alaska: U.S. Geological Survey Bulletin 442-C, p. 133-143. Knopf, Adolph, 1911, Mining in southeastern Alaska: U.S. Geological Survey Bulletin 480-D, p. 94-102. Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p. Maas, K.M., Still, J. C., and Bittenbender, P. E., 1992, Mineral investigations in the Ketchikan mining district, Alaska, 1991 - Prince of Wales Island and vicinity: U.S. Bureau of Mines Open-File Report 81-92, 69 p. Martin, G.C., 1919, Alaska Mining Industry in 1917: U.S. Geological Survey Bulletin 692-A, p. 11-42. Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712-A, p. 1-52. Myers, G.L., 1985, Geology and geochemistry of the iron-copper-gold skarns of Kasaan Peninsula, Alaska: Fairbanks, University of Alaska, M.Sc. thesis, 165 p. Roppel, Patricia, 1991, Fortunes from the earth: Manhattan, Kansas, Sunflower University Press, 139 p. Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 65 p. Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1916: U.S. Bureau of Mines Bulletin 153, 89 p. Warner, L.A., Goddard, E.N., and others, 1961, Iron and copper deposits of Kasaan Peninsula, Prince of Wales Island, southeastern Alaska: U.S. Geological Survey Bulletin 1090, 136 p. Wright, C.W., 1909, Mining in southeastern Alaska: U.S. Geological Survey Bulletin 379-B, p. 67-86. Wright, C.W., 1915, Geology and ore deposits of Copper Mountain and Kasaan Peninsula, Alaska: U.S. Geological Survey Professional Paper 87, 110 p. Wright, C.W., and Paige, Sidney, 1908, Copper deposits on Kasaan Peninsula, Prince of Wales Island: U.S. Geological Survey Bulletin 345, p. 98-115. Wright, F.E., and Wright, C.W., 1908, The Ketchikan and Wrangell mining districts, Alaska: U.S. Geological Survey Bulletin 347, 210 p.

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