Rae-Wallace; Alaska Free Gold Mining Co.; Rosenthal Mine, Willow Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Rae-Wallace; Alaska Free Gold Mining Co.; Rosenthal Mine	Mine
Willow Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: Near head of Sydney Creek, marked with quarry symbol and labeled 'Rae-Wallace Mine' on the Anchorage D-6 1:63,360-scale topographic map. Accurate within 400 ft. Locality 11 of Capps (1915), locality 22 from Cobb (1972), and locality 18 of MacKevett and Holloway (1977).
Geology: At least two quartz veins cut the Late Cretaceous Willow Creek Pluton. The first vein is 1 to 3 ft thick and strikes N 40 W, and dips 10 SW, and contains finely disseminated pyrite and irregularly distributed free gold. The other vein is 6 to 12 inches thick, strikes east, and dips 55 S; it contains pyrite, arsenopyrite, and presumably gold (Capps, 1919). The veins are so close to the mountain top that the amount of mineralized material is small. 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).
Workings: Explored by several hundred feet of underground workings in at least two tunnels and some open cuts. Development work began in 1914. Two tunnels with aggregate length of 125 ft were dug by 1915. By 1917, one tunnel was extended to a length of 330 ft (Capps, 1914; 1915; 1916; 1919). No activity reported since 1929, when mine activity was intermittent and a little ore was mined.
Age: Late Cretaceous or younger; veins cut the Late Cretaceous Willow Creek Pluton.
Alteration: Some vein material shows oxidation (Capps, 1919). 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: Amount of production unknown, but probably small.

Commodities (Major) - Au
Development Status: Yes; small
Deposit Model: Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

Other Databases

Link to USGS - Alaska:	AN042

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References