Last Chance

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au; Pb; Sb
Other commodities Ag
Ore minerals galena; gold; pyrite; stibnite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-2
Latitude 64.7215
Longitude -165.5381
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Last Chance prospect is on the south side of the headwaters of Last Chance Creek at an elevation of about 650 feet. This is 1 mile northeast of the divide between Last Chance Creek and Penny River. The prospect is located to within about 500 feet. It is the same prospect as locality 19 of Cobb (1972 [MF 463], 1978 [OFR 78-93]) but Cobb's location is about a half mile too far to the east.

Geologic setting

Geologic description

The Last Chance prospect consists of an adit driven south-southwest on the Penny River fault or a splay of the fault. The prospect was first reported by Smith (1908, p. 345). Mertie (1918 [B 662-I, p. 446]) also mentions it ,but it appears unlikely that the prospect was visited by the U.S. Geological Survey at that time. The vein at the prospect was variously reported as 4 or 5 feet wide. It contained galena, pyrite, and stibnite with quartz and ankerite. Gold and silver were reported in assays, but the presence of native gold is uncertain. A 70-foot adit was driven on the vein. It is inferred from the lack of further development that the gold content of the vein was low, but there is abundant quartz float at the prospect. Sainsbury and others (1972 [OFR 72-321]) show placer gold mine workings to be present on Last Chance Creek for about 1 mile downstream from near this prospect. The prospect was relocated by a Kennecott Exploration Company in 1990; it is similar to the nearby Christophosen prospect (NM143). Country rock at the prospect is the chlorite-rich metaturbidite and marble unit of Bundtzen and others (1994).
Geologic map unit (-165.540718048951, 64.7207351398559)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Mid-Cretaceous or younger; host structure crosscuts rocks metamorphosed in the mid-Cretaceous.

Production and reserves

Workings or exploration The prospect was discovered by G. Christophosen, who was apparently very active in the area before 1915 (see also NM141 and NM143). A 70-foot adit was driven on the vein. It is inferred from the lack of further development that the gold content of the vein was low,but there is abundant quartz float at the prospect. The vein is in a strong structure.
Indication of production Undetermined

References