Gold Occurrences, Helen Todd Lake, Annette Island, Ketchikan Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi
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Latitude & Longitude (WGS84):
55° 13' 22'' North , 131° 29' 48'' West
Latitude & Longitude (decimal):
Type:
Group of Occurrences
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Metlakatla | 1,405 (2017) | 11.6km |
| Saxman | 417 (2017) | 12.3km |
| Ketchikan | 8,197 (2017) | 16.3km |
Location: This site represents two occurrences about 0.3 mile apart on the east shore of the unnamed lake immediately north of Helen Todd Lake. The occurrences are in section 2, T. 77 S., R. 92 E., of the Copper River Meridian. The map site is at the midpoint between these occurrences. The site corresponds to loc. 13 in Berg (1972 [I 684]), and loc. 9 in Karl (1992). The location is accurate within 0.15 mile.
Geology: The country rocks in the area of this site are Upper Jurassic or Cretaceous flyschlike metasedimentary rocks that are gradationally interbedded with andesitic or basaltic metatuff (Berg, 1972; Berg and others, 1988; Karl, 1992). The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences consist of pyrite-bearing, vuggy quartz veins and ribbon-quartz veins up to 10 feet thick that cut gray phyllite, or form the matrix of phyllite breccia (Berg, 1972, loc. 13). A sample of ribbon quartz containing pyrite cubes assayed 4 ppm Au (Karl, 1992, loc. 9).
Workings: A sample of ribbon quartz containing pyrite cubes assayed 4 ppm Au (Karl, 1992, loc. 9).
Age: Probably Late Cretaceous or younger.
Alteration: Pyritization of tuffaceous phyllite country rock. Intermittent zones of iron staining for several hundred yards along shoreline of lake.
Commodities (Major) - Au
Development Status: None
Deposit Model: Low-sulfide Au-quartz veins (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
2 valid minerals.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| 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 | ⓘ Pyrite | FeS2 |
| Fe | Iron | |
| Fe | ⓘ Pyrite | FeS2 |
Other Databases
| Link to USGS - Alaska: | KC166 |
|---|
Other Regions, Features and Areas containing this locality
North America
- Coast MountainsMountain Range
North America PlateTectonic Plate
- Alexander DomainDomain
- Alexander TerraneVolcanic Arc
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