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Hirst-Chichagof Mine, Chichagof Mining District (Chicagof Mining District), Sitka, Alaska, USAi
Regional Level Types
Hirst-Chichagof MineMine
Chichagof Mining District (Chicagof Mining District)Mining District
SitkaCity Borough
AlaskaState
USACountry

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Key
Latitude & Longitude (WGS84):
57° 41' 5'' North , 136° 6' 14'' West
Latitude & Longitude (decimal):
Locality type:
Köppen climate type:


A former Ag-Au-Cu-Pb-Zn occurrence/mine.

The entire Chichagof Mining District is in West Chichagof-Yakobi Wilderness although there are patented claim blocks within the wilderness such as those that cover this mine.

Location: The well-known Hirst-Chichagof Mine is at the head of Kimshan Cove. Its patented and unpatented claims stretch southeast from near sea level for about a mile along the northeast flank of Doolth Mountain. For this record, the site is plotted at an elevation of 100 feet, 0.4 mile north of the center of sec. 25, T48S, R57E. It is location P-60 of Bittenbender and others (1999), location 27 of Cobb (1972, 1978), and MAS no. 0021140003 (U.S. Bureau of Land Management, 2002). The location is accurate.

Geology: Deposit Model: The deposit is polymetallic veins (Cox and Singer, 1986; model 22c).

The most productive mines and most of the significant prospects on western Chichagof Island are centered on Doolth Mountain in an approximately 4-square-mile area between the head of Klag Bay and south of Kimshan Cove (Reed and Coats, 1941; Bittenbender and others, 1999). The area is underlain by the Cretaceous Sitka Graywacke which consists of massive, thick-bedded, and slaty graywacke, locally interbedded with lenticular layers of recrystallized basalt ('greenstone') (Johnson and Karl, 1985).

The strata generally strike northwest and dip steeply southwest. They are intruded by felsic and mafic dikes, but no granitic plutons are exposed in the area. All of the rocks are regionally metamorphosed to prehnite-pumpellyite grade, and some of the dikes are silicified near the orebodies (Reed and Coats, 1941). The principal structures in the area are numerous northwest-striking, steeply-dipping faults. Two of them--the Hirst and Chichagof faults--and splays ('splits') from them, localized the principal ore bodies, particularly where variations in the intersections of faults and bedding created potential openings that allowed increased fluid migration and mineralization (Bittenbender and others, 1999).

The deposits are auriferous quartz veins containing pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and native gold, most of which is free-milling. The quartz is accompanied by a little calcite, and a little gold occurs in the wallrocks of the veins. The productive veins commonly have a ribbon structure, characterized by graphitic partings, and commonly are accompanied by graphitic gouge. Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).

The first claim on what was to become the Hirst-Chichagof Mine was located in 1905, and from 1922 to 1933, the mine produced 131,000 ounces of gold and 33,000 ounces of silver from more than 140,000 tons of ore (Reed and Coats, 1941; Bittenbender and others, 1999). The mine closed in 1943. From 1950 to 1954, 124 ounces of gold were recovered from a mill cleanup and from mine tailings (Still and Weir, 1981).

Still and Weir report that the mine explored the Hirst Fault for about a mile along strike, and up to 2,000 feet vertically. Mining reached a depth of 1,800 feet below sea level. The workings, almost all of which are inaccessible, included an adit with four levels totaling 6,950 feet, and two shafts. The U.S. Bureau of Mines (Still and Weir, 1981) estimated the remaining resources on the basis of examinations in 1978 and 1979 of surface and accessible underground workings. Their estimates include 30,000 tons of material with an average grade of 1.0 ounce of gold per ton; 70,000 tons with an average grade of 0.25 ounce of gold per ton; and 70,000 tons of tailings with an average grade of 0.14 ounce of gold per ton. From 1981 to 1983, private interests explored the workings and evaluated the tailings. In 1986, other interests drove a 160-foot crosscut and established a drill station. By 1988, they had rehabilitated some underground workings and completed about 3,215 feet of core drilling to test the possible extension of the Kay oreshoot below previously developed mine levels. The work did not intersect ore. Nevertheless, they estimated the resources remaining in the ore shoot as 30,380 tons of probable, possible, and inferred ore with an average grade of 1.0 ounce per ton.

Workings: Still and Weir (1981) report that the Hirst-Chichagof Mine explored the Hirst Fault for about a mile along strike, and up to 2,000 feet vertically. Mining reached a depth of 1,800 feet below sea level. The workings, almost all of which are inaccessible, included an adit with four levels totaling 6,950 feet, and two shafts. From 1981 to 1983, private interests explored the workings and evaluated the tailings. In 1986, other interests drove a 160-foot crosscut and established a drill station. By 1988, they had rehabilitated some underground workings and completed about 3,215 feet of core drilling to test the possible extension of the Kay oreshoot below previously developed mine levels. The work did not intersect ore.

Age: Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Alteration: Dikes are silicified near orebodies.
Production: From 1922 to 1933 the Hirst-Chichagof Mine produced 131,000 ounces of gold and 33,000 ounces of silver from more than 140,000 tons of ore (Reed and Coats, 1941; Bittenbender and others, 1999). From 1950 to 1954, 124 ounces of gold were recovered from a mill cleanup and from mine tailings (Still and Weir, 1981).

Reserves: The U.S. Bureau of Mines (Still and Weir, 1981) estimated the remaining resources on the basis of examinations in 1978 and 1979 of surface and accessible underground workings. Their resource estimates include 30,000 tons of material with an average grade of 1.0 ounce of gold per ton; 70,000 tons with an average from of 0.25 ounce of gold per ton; and 70,000 tons of tailings with an average grade of 0.14 ounce of gold per ton. From 1981 to 1983, private interests explored the workings and evaluated the tailings. In 1986, other interests drove a 160-foot crosscut and established a drill station. By 1988, they had rehabilitated some underground workings and completed about 3,215 feet of core drilling to test the possible extension of the Kay oreshoot below previously developed mine levels. The work did not intersect ore. Nevertheless, they estimated the resources remaining in the Kay ore shoot as 30,380 tons of probable, possible, and inferred ore with an average grade of 1.0 ounce per ton.


Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


8 valid minerals.

Detailed Mineral List:

Arsenopyrite
Formula: FeAsS
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Calcite
Formula: CaCO3
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Chalcopyrite
Formula: CuFeS2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Galena
Formula: PbS
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Gold
Formula: Au
Reference: Rocks & Min.: 20:372.; Rocks & Min.: 20:372.; U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Pyrite
Formula: FeS2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Quartz
Formula: SiO2
Reference: Rocks & Min.: 20:372.; U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
Sphalerite
Formula: ZnS
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Arsenopyrite2.EB.20FeAsS
Chalcopyrite2.CB.10aCuFeS2
Galena2.CD.10PbS
Pyrite2.EB.05aFeS2
Sphalerite2.CB.05aZnS
Group 4 - Oxides and Hydroxides
Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Gold1.1.1.1Au
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Pyrite2.12.1.1FeS2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2

List of minerals for each chemical element

CCarbon
C CalciteCaCO3
OOxygen
O QuartzSiO2
O CalciteCaCO3
SiSilicon
Si QuartzSiO2
SSulfur
S ArsenopyriteFeAsS
S ChalcopyriteCuFeS2
S GalenaPbS
S PyriteFeS2
S SphaleriteZnS
CaCalcium
Ca CalciteCaCO3
FeIron
Fe ArsenopyriteFeAsS
Fe ChalcopyriteCuFeS2
Fe PyriteFeS2
CuCopper
Cu ChalcopyriteCuFeS2
ZnZinc
Zn SphaleriteZnS
AsArsenic
As ArsenopyriteFeAsS
AuGold
Au GoldAu
PbLead
Pb GalenaPbS

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Wright, C.W. (1907) Lode mining in southeastern Alaska: USGS Bulletin 314: 47-72.
Knopf, A. (1912) The Sitka mining district, Alaska: USGS Bulletin 504, 32 p.
Overbeck, R.M. (1919) Geology and mineral resources of the west coast of Chichagof Island: USGS Bulletin 692-B: 91-136.
Buddington, A.F. (1925) Mineral investigations in southeastern Alaska: U.S. Geological Survey Bulletin 773-B, p. 71-139.
Humphrey, H.B. (1936) Hirst-Chichagof Mine: Unpublished U. S. Bureau of Mines report, 7 p. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska).
Humphrey, H.B. (1938) Improvements at Hirst-Chichagof Mine, Kimshan Cove, Alaska: Unpublished U. S. Bureau of Mines report, 3 p., available from the Mineral Information Center, Bureau of Land Management.
Reed, J.C. (1939) Preliminary report on the ore deposits of the Chichagof Mining District, Alaska: American Institute of Mining & Metallurgy, Engineering Technical Publication 1051, 20 p.
Fiedler, H.L. (1941) Report to the Commissioner of Mines on the inspection of the Hirst-Chichagof Mining Company, Kimshan Cove, Alaska: Unpublished report, 16 pages. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska).
Kazee, H M. (1941) Hirst-Chichagof Mining Company: Unpublished report, 10 p. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska).
Reed, J.C., Coats, R.R. (1941) Geology and ore deposits of the Chichagof mining district, Alaska: USGS Bulletin 929, 148 p.
Thorne, R.L. (1967) Chichagof Mining District, Sitka quadrangle, southeastern Alaska: Unpublished U. S. Bureau of Mines Situation report, 5 p.
Cobb, E.H. (1972), Metallic mineral resources map of the Sitka quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-467, scale 1:250,000.
Cobb, E.H. (1978) Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Sitka quadrangle: USGS Open-File Report 78-450, 124 pages.
Metz, P.A. (1978) Chichagof and Hirst-Chichagof Mines, Chichagof Mining District, Alaska: U.S. Bureau of Mines Summary Report, 19 p.
Still, J.C., Weir, K.R. (1981) Mineral land assessment of the west portion of western Chichagof Island, Alaska: U. S. Bureau of Mines Open-File Report 89-81, 168 p.
Juneau, A.K.. Johnson, B.R, Karl, S.M. (1985) Geologic map of western Chichagof and Yakobi Islands, southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map 1-1506, 1 sheet, scale 1:125,000.
Dadoly, J.P. (1987) Gold mineralization in a regional metamorphic terrane: A wall-rock alteration study of the Chichagof and Hirst-Chichagof gold mines, southeast Alaska: Unpublished M. S. thesis, South Dakota School of Mines, Rapid City, South Dakota, 125 pages.
Golden Sitka Resources Incorporated (1987), Prospectus, 36 pages. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska).
Northern Miner (1988) Golden Sitka busy at Chichagof: Northern Miner: 74(24): 6.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., Taylor, C. (1995) Link between ridge subduction and gold mineralization in southern Alaska: Geology: 23(11): 995-998.
Goldfarb, R J. (1997) Metallogenic evolution of Alaska, in Goldfarb, R.J., Miller, L.D., editors, Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Goldfarb, R.J., Miller, L.D., Leach, D.L., Snee, L.W. (1997) Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., Miller, L.D., editors, Mineral Deposits of Alaska: Economic Geology Monograph 9: 151-190.
Bittenbender, P., Still, J.C., Maas, K., McDonald, M., Jr. (1999) Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
Rocks & Minerals (1`945): 20: 372.
U.S. Bureau of Land Management (2002) Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html] .

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