Blacksand Beach Occurrence, Yakutat Mining District, Yakutat, Alaska, USAi
Regional Level Types | |
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Blacksand Beach Occurrence | Occurrence |
Yakutat Mining District | Mining District |
Yakutat | City Borough |
Alaska | State |
USA | Country |
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Latitude & Longitude (WGS84):
59° 22' 48'' North , 139° 25' 47'' West
Latitude & Longitude (decimal):
Type:
KΓΆppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Yakutat | 662 (2014) | 25.0km |
Mindat Locality ID:
196540
Long-form identifier:
mindat:1:2:196540:0
GUID (UUID V4):
c5dc0808-6bba-4ff1-842e-878801364349
The beach is in the Tongass National Forest.
Location: The Blacksand beach placer is about 10 miles long extending northwesterly between the Ahrnklin and Dangerous Rivers. The coordinate location is the approximate mid-point of the beach, which extends northwesterly into the Yakutat B-5 quadrangle. The deposit coincides with a named geographic feature (Blacksand Spit); it is location 7 of Cobb (1972). It is southeast of the Situk beach placer (YA007).
Geology: The Blacksand deposit is on a modern spit that extends along the coast line for about 10 miles. It was derived by high-energy reworking of underlying unconsolidated sediments of Holocene age (Foley and others, 1995; Reimnitz and Plafker, 1976) and from the density stratification of the alluvium constantly brought down by the Ahrnklin and Dangerous Rivers, which head in the Fairweather Range. Black and garnet sand lenses 0.1 to 0.2 feet thick contain interlocked magnetite-ilmenite or garnet and, more rarely, gold. Cobb (1979, p. 19) cites a reliable report of a PGE (platinum) from the mouth of the Situk River.
Workings: The beach has been mined on a small scale for many years. It was sampled by Thomas and Berryhill (1962), MacKevett and Plafker (1970; sample no. 67Apr76C), Reimnitz and Plafker (1976, samples 39, 40, and 41), and by Foley and others (1995, samples 276, 277 and 278). Thirteen beach locations were sampled by Thomas and Berryhill; their sample number 26 (table 12) contained 0.00012 ounce/cubic yard gold, 11.7 pounds/ cubic yard titania, and 25.8 pounds/cubic yard iron. Six of the thirteen samples contained 10 pounds or more of titania/cubic yard. The maximum amount of titania reported by Thomas and Berryhill was 47.4 pounds/cubic yard; maximum iron was about 150 pounds/cubic yard. Reimnitz and Plafker (1976) reported from 0.010 to 0.050 ppm gold in their samples. Gold was determined by atomic absorption, hence it may not correlate with the amount that could be recovered by placer mining and processing. Gold was not found by Foley and others (1995) in their head splits, but was reported in two of three spiral concentrates of the samples. Spiral concentrates also contained as much as 3.1 percent titanium and 1665 ppm zirconium.
Age: Holocene
Commodities (Major) - Au, Fe, Ti; (Minor) - PGE, Zr
Development Status: Yes; small
Deposit Model: Beach placer: single-cycle deposits of high-energy systems.
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
5 valid minerals.
Detailed Mineral List:
β 'Garnet Group' Formula: X3Z2(SiO4)3 |
β Gold Formula: Au |
β Ilmenite Formula: Fe2+TiO3 |
β Magnetite Formula: Fe2+Fe3+2O4 |
β Rutile Formula: TiO2 |
β Zircon Formula: Zr(SiO4) |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
β | Gold | 1.AA.05 | Au |
Group 4 - Oxides and Hydroxides | |||
β | Magnetite | 4.BB.05 | Fe2+Fe3+2O4 |
β | Ilmenite | 4.CB.05 | Fe2+TiO3 |
β | Rutile | 4.DB.05 | TiO2 |
Group 9 - Silicates | |||
β | Zircon | 9.AD.30 | Zr(SiO4) |
Unclassified | |||
β | 'Garnet Group' | - | X3Z2(SiO4)3 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | β Ilmenite | Fe2+TiO3 |
O | β Magnetite | Fe2+Fe23+O4 |
O | β Rutile | TiO2 |
O | β Zircon | Zr(SiO4) |
O | β Garnet Group | X3Z2(SiO4)3 |
Si | Silicon | |
Si | β Zircon | Zr(SiO4) |
Si | β Garnet Group | X3Z2(SiO4)3 |
Ti | Titanium | |
Ti | β Ilmenite | Fe2+TiO3 |
Ti | β Rutile | TiO2 |
Fe | Iron | |
Fe | β Ilmenite | Fe2+TiO3 |
Fe | β Magnetite | Fe2+Fe23+O4 |
Zr | Zirconium | |
Zr | β Zircon | Zr(SiO4) |
Au | Gold | |
Au | β Gold | Au |
Other Databases
Link to USGS - Alaska: | YA008 |
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