Hoffman Prospect, Alexander Prospect, and Melville Prospect, Smugglers Creek, Cleveland Peninsula, Ketchikan Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi
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Latitude & Longitude (WGS84):
55° 37' 45'' North , 132° 1' 30'' West
Latitude & Longitude (decimal):
Type:
Group of Prospects
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Thorne Bay | 483 (2017) | 31.8km |
| Ketchikan | 8,197 (2017) | 39.8km |
| Saxman | 417 (2017) | 43.9km |
Location: This site is about at the center of three old prospects with similar geology--the Alexander, Hoffman, and Melville--in an area of about one-quarter square mile. The site is about 2.2 miles north-northwest of the mouth of Smugglers Creek, near the center of the NE1/4 section 14, T. 72 S., R. 87 E.
Geology: This site consist of a group of three neighboring prospects--Alexander, Hoffman, and Melville--that date from before WWI and have similar geology (Wright and Wright, 1908). At the Alexander prospect, a 45-foot tunnel exposes a quartz vein 6 inches to 3 feet wide that strikes north and dips 45W; it intersects the schistosity of folded greenstone and slate. At the Hoffman prospect, an irregular quartz vein about 5 feet thick strikes N5W and dips steeply west. It is exposed in a 21-foot tunnel in faulted greenstone and schist. Minor pyrite occurs in the quartz vein and in the wallrock. At the Melville prospect, a quartz vein cuts folded and faulted slate and greenstone. A little ore was mined from a short tunnel and treated in an arrastre. The deposit at the Melville prospect is unusual in the Helm Bay district because it contains arsenopyrite rather than pyrite in the quartz vein and wallrock. There is no indication of any exploration on any of these prospects since before WWI. The best of several recent samples of these prospects contained 2,642 parts per billion gold across 5 inches of mineralization (Bittenbender and others, 1993; Maas and others, 1995). The rocks in the area consist of metamorphosed andesite, basalt, agglomerate, and tuff, and minor flysch, shale, and phyllite. Eberlein and others (1983) and Brew (1996) consider them to be Paleozoic or Mesozoic in age; Gehrels and Berg (1992) tentatively mapped them as Jurassic or Cretaceous.
Workings: Each of these three prospects was explored by short adits, the longest 45 feet long, that were driven prior to 1908.
Age: The quartz veins cut country rocks that may be as young as Cretaceous or as old as Paleozoic.
Production: No production from the Alexander and Hofman prospects; the Melville produced a small amount of ore prior to 1908 that was treated in a local arrastre.
Reserves: None.
Commodities (Major) - Au
Development Status: Yes; small
Deposit Model: Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
3 valid minerals.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Quartz | SiO2 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| S | Sulfur | |
| S | ⓘ Arsenopyrite | FeAsS |
| S | ⓘ Pyrite | FeS2 |
| Fe | Iron | |
| Fe | ⓘ Arsenopyrite | FeAsS |
| Fe | ⓘ Pyrite | FeS2 |
| As | Arsenic | |
| As | ⓘ Arsenopyrite | FeAsS |
Other Databases
| Link to USGS - Alaska: | CR077 |
|---|
Other Regions, Features and Areas containing this locality
North America
- Coast MountainsMountain Range
North America PlateTectonic Plate
- Alexander TerraneVolcanic Arc
- Taku DomainDomain
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References
Wright, F.E.; Wright, C.W. (1906) Report on Progress of Investigations of Mineral Resources of Alaska in 1905. Bulletin 284. US Geological Survey p.30-54. doi:10.3133/b284
Wright, Fred Eugene; Wright, Charles Will (1908) The Ketchikan and Wrangell mining districts, Alaska. U.S. Geological Survey Bulletin 347. U.S. Geological Survey 210pp.
Cobb, Edward Huntington (1978) Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Craig Quadrangle, Alaska. Open-File Report Vol. 1978 (78-869). US Geological Survey 262pp. doi:10.3133/ofr78869
