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.

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Commodity List

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Mineral List

8 valid minerals.