Lost River endogreisen deposit, Lost River Mine, Lost River Valley, Port Clarence Mining District, Nome Census Area, Alaska, USAi
Regional Level Types | |
---|---|
Lost River endogreisen deposit | Mine |
Lost River Mine | Mine |
Lost River Valley | Basin |
Port Clarence Mining District | Mining District |
Nome Census Area | Census Area |
Alaska | State |
USA | Country |
This page is currently not sponsored. Click here to sponsor this page.
Latitude & Longitude (WGS84):
65° 28' 26'' North , 167° 9' 20'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Mindat Locality ID:
198601
Long-form identifier:
mindat:1:2:198601:6
GUID (UUID V4):
fa968e91-c4ed-4957-b15d-51a3ac5d2da2
Location: The Lost River Mine area includes the Cassiterite dike exogreisen deposit (TE048), the Lost River Mine skarn deposit (TE049), the Lost River Mine endogreisen deposit (TE050), and the Ida Bell dike exogreisen deposit (TE051). The Lost River endogreisen deposit is located in a subsurface granite cupola below the Lost River skarn deposit. The skarn is exposed along and east of Cassiterite Creek at elevations of 275 to 400 feet about 0.9 miles upstream from the creek's confluence with Lost River. The upper part of the endogreisen is within 100 to 200 feet of the surface whereas deeper parts extend to depths of 750 feet or more. This deposit was included as part of locality 8 by Cobb and Sainsbury (1972). References were summarized under the name 'Lost River' by Cobb (1975).
Geology: The Lost River endogreisen deposit is developed at the roof of a highly differentiated, fine-grained granite cupola and in sheeted zones at depth within the cupola. The Lost River skarn deposit is developed in Ordovician limestone country rocks adjacent to and above the endogreisen deposit. Late hydrothermal breccia, with mica- and clay-rich matrices, have been superimposed on both endogreisen and skarn (Dobson, 1982, figure 4). The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983). Fine-grained, leucocratic granite collected from a Lost River Mine dump has been dated at 80.2 +/- 2.9 my (Hudson and Arth, 1983, p.769). As described by Dobson (1982), the roof greisen is mica-rich, commonly 30 to 60% muscovite and probably zinnwaldite. The mica-rich greisen merges upward with hydrothermal breccias having a mica-rich matrix. Downward the mica-rich roof greisen gives way to quartz-rich greisen that characteristically contains tourmaline and sulfide minerals including pyrite, arsenopyrite, galena, sphalerite, and chalcopyrite. There are gradations from unaltered to completely greisenized granite but in places only thin, quartz-arsenopyrite, quartz-tourmaline, and greisen veins are present in granite. The roof greisen as mapped by Dobson (1982, figures 4 and 5), has dimensions of about 120 x 400 x 1,000 feet. Sainsbury's (1964, plate 9) compilation of grade data for this part of the deposit indicates that the general grade is a few tenths of a percent tin and a few hundreths of a percent WO3. The deeper sheeted greisen was defined by Dobson (1982, figure 4) but it is primarily known from intercepts in two diamond drill holes completed by Teasgulf Inc. in 1979. Hole TG 2 (collared at 275 feet elevation, azimuth of N 19 E, inclined at 67.5 degrees, and a total depth of 1,012 feet) encountered: (1) 0.19% tin, 0.74% copper, 0.95% lead, 4.32% zinc, 2.73 opt silver, and 0.01% WO3 from 633 to 638 feet; (2) 1.21% tin, 0.05% copper, 0.06% lead, 0.03% zinc, 0.18 opt silver, and 0.06% WO3 from 638 to 647 feet; (3) 0.84% tin, less than 0.03% copper, 0.18% lead, 0.43% zinc, 0.27 opt silver, and 0.01% WO3 from 800.1 to 814.5 feet; and (4) 1.33% tin, less than 0.03% copper, less than 0.04% lead and zinc, 0.04 opt silver, and 0.05% WO3 from 814.5 to 823.6 feet. Hole TG 3 (collared at 321 feet elevation, azimuth of N 19 E, inclined at 64.5 degrees, and a total depth of 1,037 feet) encountered: (1) 0.28% tin, 0.08% copper, 0.78% lead, 0.80% zinc, and 1.75 opt silver (tungsten was not determined) from 778.5 to 789.8 feet; and (2) 0.88% tin, 0.08% copper, 0.20% lead, 2.13% zinc, and greater than 3.4 opt silver (tungsten was not determined) from 796.3 to 801.4 feet. Other zones of weaker tin metallization and weaker to stronger base metal and silver metallization are present in these holes. The metallization is in highly silicified zones with sulfide minerals, tourmaline, and fluorite in granite.
Workings: This prospect has been explored by 750 feet of underground workings of the Lost River mine (32 and 195 crosscuts, Calcite drift, and 190 raise; Sainsbury, 1964, plate 9). The upper roof greisen has been encountered by many USBM and Lost River Mining Corporation drill holes and the deeper sheeted greisen zones hve been encountered by two Texasgulf Inc diamond drill holes.
Age: The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983). Fine-grained, leucocratic granite collected from a Lost River Mine dump has been dated at 80.2 +/- 2.9 my (Hudson and Arth, 1983, p.769).
Alteration: There is a well-developed quartz-tourmaline-fluorite greisen at depth, a mica-rich greisen in the roof zone, and both mica- and clay-matix hydrothermal breccias above the roof zone. The greisen types appear to merge with one another and the breccias are late, overprinting assemblages.
Production: Production from the Lost River Mine has been from the Cassiterite dike exogreisen deposit (TE048).
Reserves: Resource estimates have not been separately determined for the endogreisen deposits; grades are commonly a few tenths percent tin and a few hundreths percent WO3 although some greisen sheets at depth have higher tin grades, base metals, and silver in places.
Commodities (Major) - Sn; (Minor) - Ag, Cu, Pb, Zn, W
Development Status: None
Deposit Model: Endogreisen including roof and sheeted greisen. Tin greisen model (15c) of Cox
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
10 valid minerals.
Detailed Mineral List:
ⓘ Arsenopyrite Formula: FeAsS |
ⓘ Cassiterite Formula: SnO2 |
ⓘ Chalcopyrite Formula: CuFeS2 |
ⓘ Fluorite Formula: CaF2 |
ⓘ Galena Formula: PbS |
ⓘ Muscovite Formula: KAl2(AlSi3O10)(OH)2 |
ⓘ Muscovite var. Sericite Formula: KAl2(AlSi3O10)(OH)2 |
ⓘ Pyrite Formula: FeS2 |
ⓘ Quartz Formula: SiO2 |
ⓘ Sphalerite Formula: ZnS |
ⓘ Topaz Formula: Al2(SiO4)(F,OH)2 |
ⓘ 'Tourmaline' Formula: AD3G6 (T6O18)(BO3)3X3Z |
ⓘ 'Wolframite Group' |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 2 - Sulphides and Sulfosalts | |||
---|---|---|---|
ⓘ | Sphalerite | 2.CB.05a | ZnS |
ⓘ | Chalcopyrite | 2.CB.10a | CuFeS2 |
ⓘ | Galena | 2.CD.10 | PbS |
ⓘ | Pyrite | 2.EB.05a | FeS2 |
ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
Group 3 - Halides | |||
ⓘ | Fluorite | 3.AB.25 | CaF2 |
Group 4 - Oxides and Hydroxides | |||
ⓘ | Quartz | 4.DA.05 | SiO2 |
ⓘ | Cassiterite | 4.DB.05 | SnO2 |
ⓘ | 'Wolframite Group' | 4.DB.30 va | |
Group 9 - Silicates | |||
ⓘ | Topaz | 9.AF.35 | Al2(SiO4)(F,OH)2 |
ⓘ | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
ⓘ | var. Sericite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
Unclassified | |||
ⓘ | 'Tourmaline' | - | AD3G6 (T6O18)(BO3)3X3Z |
List of minerals for each chemical element
H | Hydrogen | |
---|---|---|
H | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
H | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
H | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
B | Boron | |
B | ⓘ Tourmaline | AD3G6 (T6O18)(BO3)3X3Z |
O | Oxygen | |
O | ⓘ Cassiterite | SnO2 |
O | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
O | ⓘ Quartz | SiO2 |
O | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
O | ⓘ Tourmaline | AD3G6 (T6O18)(BO3)3X3Z |
O | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
F | Fluorine | |
F | ⓘ Fluorite | CaF2 |
F | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
Al | Aluminium | |
Al | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
Al | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
Al | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
Si | Silicon | |
Si | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
Si | ⓘ Quartz | SiO2 |
Si | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
Si | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
S | Sulfur | |
S | ⓘ Arsenopyrite | FeAsS |
S | ⓘ Chalcopyrite | CuFeS2 |
S | ⓘ Galena | PbS |
S | ⓘ Pyrite | FeS2 |
S | ⓘ Sphalerite | ZnS |
K | Potassium | |
K | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
K | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
Ca | Calcium | |
Ca | ⓘ Fluorite | CaF2 |
Fe | Iron | |
Fe | ⓘ Arsenopyrite | FeAsS |
Fe | ⓘ Chalcopyrite | CuFeS2 |
Fe | ⓘ Pyrite | FeS2 |
Cu | Copper | |
Cu | ⓘ Chalcopyrite | CuFeS2 |
Zn | Zinc | |
Zn | ⓘ Sphalerite | ZnS |
As | Arsenic | |
As | ⓘ Arsenopyrite | FeAsS |
Sn | Tin | |
Sn | ⓘ Cassiterite | SnO2 |
Pb | Lead | |
Pb | ⓘ Galena | PbS |
Other Databases
Link to USGS - Alaska: | TE050 |
---|
Other Regions, Features and Areas containing this locality
North America PlateTectonic Plate
- Brooks-Seward DomainDomain
This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.