Mabel

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Mo; Pb
Ore minerals arsenopyrite; chalcopyrite; galena; gold; molybdenite; pyrite; sphalerite; tellurides; tetrahedrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale AN
Quadrangle map, 1:63,360-scale D-6
Latitude 61.798
Longitude -149.215
Nearby scientific data Find additional scientific data near this location
Location and accuracy 1.3 miles northwest of confluence of Reed Creek and Little Susitna River. Marked with adit symbol and labeled 'Mabel Mine' on the Anchorage D-6 1:63,360-scale topographic map. Accurate within 400 ft. Locality 25 from Cobb (1972) and locality 18 of MacKevett and Holloway (1977).

Geologic setting

Geologic description

Quartz vein, up to 10 ft thick, cuts the Late Cretaceous Willow Creek Pluton. The vein pinches, swells, and breaks up into narrow stringers along strike (Ray, 1933). Minerals in the vein include free gold, arsenopyrite, chalcopyrite, galena, molybdenite, pyrite, sphalerite, unconfirmed tellurides and tetrahedrite. The strike of the vein is usually north and dip ranges from 23 to 66 W, with the most common dip between 35 and 45 W. Vein is offset by two parallel normal faults that strike N 55 W, and dip 74 NE (Ray, 1954). Some of the ore shoots are terminated by these faults. Rocks are reported to show right lateral displacement with net offsets of 100-150 ft. Movement in the fissure containing the vein was, based drag and offset of aplite dikes, reverse.
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. Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).
Geologic map unit (-149.217208894638, 61.7974707082105)
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; the quartz vein cuts the Late Cretaceous Willow Creek Pluton.
Alteration of deposit Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).

Production and reserves

Workings or exploration First staked in 1911. Development included open cuts and stripping which traced the vein for about 2,000 ft, plus at least 490 ft of underground workings most of which were below the main level. Site had mill, aerial tram, and a cyanide plant. Ore was taken to the mill by aerial tram, the tailings were saved for future treatment. Most of the mining was south of the Mabel fault, along a major transverse fault. Six tons of ore was shipped to Tacoma in 1912. Intermittent mining and development to 1917, mine produced continually from 1917-1930, and worked intermittently from 1931-1947. Ray (1933) indicated production probably worth more than $100,000 (about 4,840 fine oz of Au based on gold at $20.66/oz). Ray (1954) indicated that future development is likely to be expensive and difficult because of lack of data on faulting.
Indication of production Yes; small
Production notes Smith (1929) indicated that Mabel mine was one of the principal producing mines in the district. The production probably totaled 4,840 oz of Au by 1933 (Ray, 1933). Stoll (1997) estimated that the mine yielded around 16,000 oz of gold.

Additional comments

Further development would require finding the extensions of the main vein north of the Mabel fault. This would be difficult and expensive since the vein has probably been down-faulted significantly below the level of present workings (Ray, 1954).

References