| Main commodities | Au |
|---|---|
| Ore minerals | arsenopyrite; gold; pyrite |
| Gangue minerals | quartz |
| Quadrangle map, 1:250,000-scale | AN |
|---|---|
| Quadrangle map, 1:63,360-scale | D-6 |
| Latitude | 61.791 |
| Longitude | -149.243 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | 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). |
Geologic descriptionAt 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). | |
| Geologic map unit | (-149.245210572635, 61.7904704274275) |
|---|---|
| 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 | 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). |
| Workings or exploration | 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. |
|---|---|
| Indication of production | Yes; small |
| Production notes | Amount of production unknown, but probably small. |
| MRDS Number | A011624 |
|---|---|
| Reporters | D.P. Bickerstaff (USGS contractor); S.W. Huss (USGS) |
| Last report date | 7/30/1998 |