Gold Cord

Mine, Active

Alternative names

Gold Cord Mining, Milling, and Power Co.
Golden Bear Mining Co.

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Pb; W; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; pyrite; scheelite; sphalerite; tetrahedrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale AN
Quadrangle map, 1:63,360-scale D-7
Latitude 61.797
Longitude -149.286
Nearby scientific data Find additional scientific data near this location
Location and accuracy At headwaters of East Fork Fishhook Creek, marked with an adit symbol and labeled 'Gold Cord Mine' on the Anchorage D-7 1:63,360-scale topographic map. Accurate within 400 ft. Locality 14 of Cobb (1972) and locality 11 of MacKevett and Holloway (1977).

Geologic setting

Geologic description

The principal vein mined is in a shear zone as much as 25 ft wide in Late Cretaceous quartz diorite of the Willow Creek Pluton. The Willow Creek Pluton is a zoned pluton: the outer part consists of hornblende quartz diorite and lesser hornblende tonalite; the core consists of hornblende-biotite granodiorite, and lesser hornblende-biotite quartz monzodiorite and biotite quartz monzonite. Quartz is present along the foot wall and hanging wall which are separated by sheared quartz diorite, some of which is essentially unaltered. The vein strikes about N 10 W, and dips 30 to 42 W (Ray, 1933). Numerous other shear zones are present and are generally about 3 to 4 ft wide. These contain reticulating quartz veins and mineralized, altered quartz diorite (Chapin, 1920). Wall-rock alteration is intense and consists of replacement by the usual hydrothermal minerals in the district - chlorite, pyrite, sericite, ankerite, and a little calcite (Ray, 1933). Workings in the Gold Cord mine are probably the most difficult in the mining district. Due to the relatively greater number and arrangement of post-mineralization faults. The most important of the faults is the Gold Cord Fault, a major transverse fault striking N 65 W, and dipping 80 to 85 SW. This fault system is about 40 feet wide on the 100 and 400 levels but is 120 feet wide on the 200 level of the mine. The fault material is mostly comminuted, strongly altered quartz diorite. A number of minor transverse faults also cut the vein. These normal faults trend northwesterly and dip steeply to the northeast; displacements are generally less than 15 feet. The geology is further complicated by several normal and reverse faults (Ray, 1954). The property north of the Gold Cord Fault may prove favorable due to the absence of any major faults.
Ore grade ranged from about 0.1 to 9 oz/ton Au. Most assay values were between 0.75 and 4 oz/ton Au (converted from dollar values given in Ray (1933)). During a 1984 U.S. Bureau of Mines investigation (Kurtak, 1986), a 1.8-ft-wide sample across a quartz vein in the 4,900 ft adit (late 1940s workings) contained 13 ppm gold (0.38 oz/ton).
Geologic map unit (-149.288212183027, 61.7964714805292)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Late Cretaceous or younger; veins cut the Late Cretaceous Willow Creek Pluton.
Alteration of deposit Wall-rock alteration is intense and consists of replacement by the usual hydrothermal minerals in the district: chlorite, pyrite, sericite, ankerite, and a little calcite (Ray, 1933).

Production and reserves

Workings or exploration
First staked in 1915 by Byron and Charles Bartholf. Development work appears to have been sporadic for many years, records indicate 'real' activity began around 1931 (Ray, 1954). By 1933 the camp consisted of a mill (crusher, 10-ton Denver mill, amalgamating plates, and a small concentration table), shops, and living quarters (Ray, 1933). The bulk of the gold produced from the mine was during the six year period from the winter of 1931 through 1937 (Stoll, 1997). Ray (1954) reports that the mine was developed by at least 2,500 ft of workings on several levels over a vertical distance of 200 ft. In 1947 and 1948 two veins near the top of the mountain above the Gold Cord mine were explored by drifting, but no significant amount of gold was found.
The property has been drilled in attempts to locate faulted-out sections of vein and prospect adits driven on other veins have not been particularly successful. The property north of Gold Cord Fault may prove favorable due to the absence of any major faults.
Ore grade ranged from about 0.1 to 9 oz/ton Au. Most assay values between 0.75 and 4 oz/ton Au (assay converted from dollar values reported by Ray, 1933). One batch of 11 tons of ore contained 10.9 oz (1 oz/ton) of gold (Brooks, 1925). During a 1984 U.S. Bureau of Mines investigation (Kurtak, 1986), a 1.8-ft-wide sample across a quartz vein in the 4,900 ft adit (late 1940s workings) contained 13 ppm gold (0.38 oz/ton).
In 1998, Dan Renshaw continued driving a new adit in search of favorable ore at the Gold Cord mine.
Indication of production Yes; small
Production notes From discovery through 1949, mainly between 1931 and 1938, the Gold Cord lode produced around 16,000 ounces of gold (Stoll, 1997).

Additional comments

The site has also been referenced in the literature as Golden Bear Mining Co. and (Gold Cord) Mining, Milling, and Power Co.

References