Unnamed (at head of locally named Sargent Creek

Prospect, Probably inactive

Alternative names

possibly McNeil No. 7 claim)

Commodities and mineralogy

Main commodities Fe
Ore minerals magnetite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale IL
Quadrangle map, 1:63,360-scale A-5
Latitude 59.143
Longitude -154.6548
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an average elevation of about 2,050 feet at the head of locally-named Sargent Creek (Richter and Herreid,1965). The prospect is in the N1/2 NW1/4 sec. 15, T. 12 S., R. 32 W., Seward Meridian. It is locality 6 of Richter and Herreid. The location is accurate for the approximate center of this six-acre prospect area.

Geologic setting

Geologic description

The mineral deposits at this prospect are magnetite-rich skarns (tactites) in locally calcic, intermediate to mafic volcanic rocks and subordinate sedimentary rocks of the Jurassic Talkeetna Formation (Richter and Herreid, 1965; Detterman and Reed, 1980).
The prospect comprises ten exposed bodies of magnetite-quartz skarn in an area of about six acres (Richter and Herreid, 1965). The largest body is nearly pure magnetite and is about 75 feet long and 10 feet wide. The other bodies are smaller and contain as much as 50 percent quartz. A ground-based magnetic survey suggests that the masses are isolated pods, not connected to a large mass at depth (Richter and Herreid, 1965, p. 14). The prospect appears to be the one described by Jasper (1956, p. 9), who reported two magnetite-rich pods, one containing an estimated 10,000 tons, and the other 5,000 tons, of ore. Richter and Herreid (1965) estimated 100 tons per vertical foot in the largest exposed body.
Geologic map unit (-154.656916742556, 59.1423096697065)
Mineral deposit model Fe skarn (Cox and Singer, 1986; model 18d).
Mineral deposit model number 18d
Age of mineralization Probably Jurassic.
Alteration of deposit Contact-metasomatic replacement of calcic volcanic and sedimentary(?) rocks by magnetite and quartz.

Production and reserves

Workings or exploration Exploration includes detailed geologic mapping and a ground-based magnetic survey by Richter and Herreid, (1965). There are no reports of any workings.
Indication of production None
Reserve estimates Jasper (1956) estimated a total of 15,000 tons of magnetite ore in two bodies. Richter and Herreid (1965) estimated 100 tons per vertical foot in the largest exposed body.

References