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Brown Prospect, Admiralty Mining District, Hoonah-Angoon Census Area, Alaska, USAi
| Regional Level Types | |
|---|---|
| Brown Prospect | Prospect |
| Admiralty Mining District | Mining District |
| Hoonah-Angoon Census Area | Census Area |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
57° 29' 26'' North , 134° 7' 8'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Angoon | 456 (2017) | 27.8km |
The prospect is now within the Wilderness Area of the Admiralty Island National Monument that is closed to mineral exploration and development.
Location: The Brown prospect is at an elevation of about 1,000 feet, about 1.7 miles north of the southwest arm of Gambier Bay. The prospect is 0.4 mile southwest of the center of sec. 36, T. 50 S., R. 70 E. It is location 71 of Cobb (1972, 1978) and MAS no. 0021140035 (U.S. Bureau of Land Management, 2002). The location probably is accurate within 0.5 mile.
Geology: The Brown prospect is near the contact of a thick Devonian marble unit within greenschist, phyllite, and metachert of the Devonian Gambier Bay Formation (Loney, 1964). The prospect has been mentioned several times over the years but apparently the only definitive descriptions are by Wright and Wright (1905) and Wright (1906). They describe the deposit as a 'ledge'--a vein probably--that was exposed for more than 200 feet in open cuts. The host rock is mostly calcareous schist and the deposit is in brecciated limestone that is replaced by quartz with small masses of pyrite and chalcopyrite. Samples had low values in copper and gold. Apparently there has been little work on the prospect since the early part of the 20th century and Wright and Wright (1905) noted that it had not been active for several years before 1904.
Workings: The deposit was explored before 1904 by several trenches.
Age: Devonian or younger based on the age of the host rock.
Commodities (Major) - Au, Cu
Development Status: None
Deposit Model: Limestone replaced by quartz with low copper and gold values.
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 | |||
|---|---|---|---|
| ⓘ | Chalcopyrite | 2.CB.10a | CuFeS2 |
| ⓘ | 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 | ⓘ Chalcopyrite | CuFeS2 |
| S | ⓘ Pyrite | FeS2 |
| Fe | Iron | |
| Fe | ⓘ Chalcopyrite | CuFeS2 |
| Fe | ⓘ Pyrite | FeS2 |
| Cu | Copper | |
| Cu | ⓘ Chalcopyrite | CuFeS2 |
Other Databases
| Link to USGS - Alaska: | SI163 |
|---|
Other Regions, Features and Areas containing this locality
North America PlateTectonic Plate
- Alexander DomainDomain
- Alexander TerraneVolcanic Arc
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