Prospect, Inactive

Alternative names

Cape Mountain

Commodities and mineralogy

Main commodities Sn
Ore minerals cassiterite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TE
Quadrangle map, 1:63,360-scale C-7
Latitude 65.579
Longitude -168.003
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect adit (now caved) is at 1,700 feet elevation on the north side of the summit to Cape Mountain. Cape Mountain is the upland that makes up Cape Prince of Wales adjacent to Bering Strait on western-most Seward Peninsula. This is locality 1 of Cobb and Sainsbury (1972). Cobb (1975) summarized relevant references under the name 'Cape Mtn.'. It is also known as the Dieter prospect (Mulligan, 1966, p. 33).

Geologic setting

Geologic description

The Cape Mountain (Dieter) prospect is a 418 foot-long adit, now caved, driven S 72 W to intersect an area of quartz veining in the Late Cretaceous (78.8 +/- 2.9 my; Hudson and Arth, 1983, p. 769) Cape Mountain biotite granite. The prospect is near the summit of Cape Mountain which is a roof pendant of marble and interlayered schist (Sainsbury, 1972). Steidtmann and Cathcart (1922, p. 99) reported finding cassiterite-bearing quartz vein material on the adit dump but a later effort by Mulligan (1966, p. 33) was unsuccessful in duplicating this result.
The area of the prospect is in a part of the Cape Mountain biotite granite (Hudson and Arth, 1983) that has characteristics of a precursor phase rather than a mineralizing phase (Hudson and Reed, 1997, figure 3).
Geologic map unit (-168.005773562089, 65.5782172925858)
Mineral deposit model Cassiterite-quartz vein in granite? (Cox and Singer, 1986; model 15b?)
Mineral deposit model number 15b?
Age of mineralization Late Cretaceous; cassiterite and related mineralization in this area is interpretated to be linked to the evolution of the Cape Mountain 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 has not been described.

Production and reserves

Workings or exploration An adit was driven 418 feet S 72 W from a portal at 1700 feet elevation on the north side of the summit to Cape Mountain. Other surface prospect pits and short shafts were dug in the area.
Indication of production None



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.
Reporters Travis L. Hudson (Applied Geology)
Last report date 5/10/1998