|Quadrangle map, 1:250,000-scale||TE|
|Quadrangle map, 1:63,360-scale||C-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This is an area of lode cassiterite mineralization at an elevation of about 1,000 feet, that straddles the ridge separating the headwaters of Cape Creek (TE006) and Goodwin Gulch (TE004); it is the source area for most of the cassiterite in the Cape Creek (TE006) and Goodwin Gulch (TE004) placers (Mulligan, 1966, p. 22). Several different cassiterite-bearing zones in bedrock are present within an area of about 2,000 feet long in a north-south direction and 800 feet across in an east-west direction; the area includes the Canoe prospect and Percy Lode (Mulligan, 1966, p. 22). This area was not identified separately by Cobb and Sainsbury (1972). Cobb summarized relevant references under the name 'Cape Mtn.'.|
The Bartel Mine area contains the most significant lode cassiterite mineralization known in the Cape Mountain area; it is the source area for the Cape Creek and Goodwin Gulch placers that produced about 1,670 short tons of tin. The only lode production (6 short tons) from the Cape Mountain area is from the Bartel Mine.
The mineralized area straddles the contact of the Late Cretaceous Cape Mountain biotite granite (78.8 +/- 2.9 my; Hudson and Arth, 1983, p. 789) with Mississippian marble (Sainsbury, 1972). The mineralization includes cassiterite disseminated in tourmalinated granite, quartz-cassiterite grains in granite, and cassiterite-bearing lenticular pods in marble. Selvages and pods of tourmalinated granite are developed locally along fractures and discontinuous small quartz veins; felsic dikes locally have tourmalinated margins. Cassiterite forms disseminations and clots in some of the tourmalinated rocks but much of this material contains only anomalous amounts of tin. In general, tourmalination is very minor in the area (Collier, 1904, p. 39; Hudson, 1984). Cassiterite-bearing quartz veins in granite are small, discontinuous and locally developed. They have been identified in one area about 1,000 feet south of the Lucky Queen adit (Mulligan, 1966, p. 24). Here, USBM dozer trenches exposed clay-altered granite with minor quartz veins that generally contain just a few hundredths per cent tin although one 3-foot wide trench sample contained 1.34 % tin (Mulligan, 1966, p. 30). The most significant lode mineralization in the area is in the northeast contact zone of the Cape Mountain biotite granite with adjacent marble. Here discontinuous veins and pods of quartz, muscovite, and cassiterite are present along granite/marble contacts and more commonly within marble. Only minor mineralization appears to be developed solely within granite. The grade of these deposits can be very high but their individual size is small. The largest individual deposit that has been identified is about 150 feet long and a few to 66 inches wide (Heide and others, 1946). The average width of this deposit is 17 inches and the average grade (as determined from 18 trench samples) is 7.24 % tin (Heide and others, 1946, p. 10). The cassiterite is commonly in coarse aggregates of subhedral to euhedral crystals. This type of mineralization appears to be the principal source of placer cassiterite in nearby Cape Creek and Goodwin Gulch.Boron, fluorine, and arsenic geochemically characterize the mineralization in this area (Hudson, 1984, p. 12). Two high grade samples (6.3 and 11.8 % tin) collected from USBM trenches contained greater than 1,000 ppm arsenic, variable boron contents (9,380 and 235 ppm respectively), and moderate amounts of fluorine (2,800 and 650 ppm respectively). In fourteen samples from the mineralized area (including the two high grade samples above; Hudson, 1984, p. 14), base metals have low to anomalous concentrations, tungsten ranges up to 610 ppm, and tantalum ranges from 3 to 14 ppm. Hydrothermal alteration or calc-silicate development is conspicuously not widespread or extensively developed in the area. Knopf (1908, p. 37-38) describes local granite pegmatites with thin pyroxene-fluorite-quartz-calcite hornfels along contacts with marble; scheelite and pyrrohotite are present as sparse, scattered grains in this hornfels.
|Geologic map unit||(-167.961772504572, 65.5862184851169)|
|Mineral deposit model||Cassiterite-bearing veins and pods in marble, at marble/granite contacts, and in granite. Some pegmatite characteristics may be present. Generally related to tin vein model (Cox and Singer, 1986; model 15b)|
|Mineral deposit model number||15b|
|Age of mineralization||Late Cretaceous; the mineralization is interpreted to be linked to the evolution of the Cape Mountain biotite granite which has been determined to be 78.8 +/- 2.9 my old by the K/Ar method (Hudson and Arth, 1983, p. 769).|
|Alteration of deposit||Alteration at Cape Mountain is conspicuous by its absence. Clay development has been noted along fractures and bedding and minor tourmaline replacement of granite is present along some contacts. Tourmaline may also be disseminated in marble adjacent to granite. Minor skarn development includes pyroxene-fluorite +/- quartz, calcite, scheelite, scapolite, and pyrrohotite selvages in marble adjacent to small granite pegmatites. Calcite-muscovite-fluorite-tremolite rocks found on mine dumps may be a replacement selvage in marble but they are not abundant in the area. Discontinuous and small quartz veins also contain muscovite, some tourmaline, and locally abundant iron-oxide. However, many altered fractures or veins consisting of gossanous quartz+/-tourmaline contain only anomalous amounts of tin. The only sulfide mineral that is commonly present is arsenopyrite, both as disseminations in yellow-orange weathering seriate granite and in vein assemblages.|
|Workings or exploration||The adits and drifts of the Bartels Mine extended up to 1,150 feet in combined length (Steidtmann and Cathcart, 1922). Five short diamond-drill holes and several dozer trenches were completed by the USBM (Heide and others, 1946). The USBM also completed detrital cassiterite mapping on slopes peripheral to the mine area (Mulligan, 1966).|
|Indication of production||Yes; small|
|Reserve estimates||Not defined but mining has been minimal.|
|Production notes||Six short tons of tin are reported to have been produced from the Bartels Mine in 1905 or 1906 (Heide and others, 1946; Mulligan, 1966, p. 8).|
Additional commentsAlthough scattered small grains of scheelite were identified in pyroxene-fluorite hornfels/skarn by Knopf (1908, p. 38), tungsten is generally present in only anomalous amounts. Tungsten was not a significant component of placer concentrates from Cape Creek or Goodwin Gulch.
Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Teller quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-587, 130 p.
Cobb, E.H., and Sainsbury, C.L., 1972, Metallic mineral resources map of the Teller quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-426, 1 sheet, scale 1:250,000.
Collier, A.J., 1904, Tin deposits of the York region, Alaska: U.S. Geological Survey Bulletin 229, 61 p.
Heide, H.E., Wright, W.S., and Sanford, R.S., 1946, Exploration of Cape Mountain lode-tin deposits, Seward Peninsula, Alaska: U.S. Bureau of Mines Report of Investigations 3978, 16 p.
Hudson, T.L., 1984, Tin systems of Seward Peninsula, Alaska: Anchorage, Anaconda Minerals Company internal report, 51 p. (Report held by Cook Inlet Region Inc., Anchorage, Alaska)
Hudson, T.L., and Arth, J. G., 1983, Tin granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.
Knopf, Adolph, 1908, Geology of the Seward Peninsula tin deposits, Alaska: U.S. Geological Survey Bulletin 358, 71 p.
Mulligan, J.J., 1966, Tin-lode investigations, Cape Mountain area, Seward Peninsula, Alaska; with a section on petrography by W.L. Gnagy: U.S. Bureau of Mines Report of Investigations 6737, 43 p.
Sainsbury, C.L., 1972, Geologic map of the Teller quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Map I-685, 4 p., 1 sheet, scale 1:250,000.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||5/10/1998|