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Tongass Prospect, Ketchikan Gateway Borough, Alaska, USAi
| Regional Level Types | |
|---|---|
| Tongass Prospect | Prospect |
| Ketchikan Gateway Borough | Borough |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
55° 24' 32'' North , 131° 48' 32'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Ketchikan | 8,197 (2017) | 12.6km |
| Saxman | 417 (2017) | 16.8km |
| Metlakatla | 1,405 (2017) | 34.5km |
Location: The Tongass prospect is at tidewater on northeast Gravina Island, about 0.3 mile southwest of Rock Point. The site is in section 36, T. 74 S., R. 89 E., of the Copper River Meridian. It corresponds to loc. 56 in Elliott and others (1978). The location is accurate within 0.1 mile.
Geology: The country rocks on northern Gravina Island are chiefly Upper Jurassic to mid-Cretaceous andesitic and basaltic volcanic rocks that gradationally intertongue with flyschlike sedimentary rocks. The rocks are intruded by at least one pluglike body of Tertiary gabbro (Berg, 1973; Berg and others, 1988). The bedded rocks were regionally metamorphosed to low-greenschist grade in Late Cretaceous time, and subsequently contact metamorphosed to hornblende hornfels near the contact of the Tertiary gabbro. The country rocks are cut by a high-angle fault along Tongass Narrows that displays about 4 miles of right-lateral offset. The deposit is in Jurassic or Cretaceous slate and phyllite and consists of a reportedly auriferous, pyrite-bearing quartz fissure vein about one foot thick (Brooks, 1902, p. 61). The vein strikes NE and dips steeply NW, at an acute angle to the layering in the slate and phyllite.
Age: Late Cretaceous or younger.
Commodities (Major) - Au?
Development Status: None
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsGallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Gold ? | 1.AA.05 | Au |
| 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 |
| Au | Gold | |
| Au | ⓘ Gold | Au |
Other Databases
| Link to USGS - Alaska: | KC059 |
|---|
Other Regions, Features and Areas containing this locality
North America
- Coast MountainsMountain Range
North America PlateTectonic Plate
- Alexander DomainDomain
- Alexander TerraneVolcanic Arc
USA
- Alaska
- Ketchikan Mining DistrictMining District
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