Unnamed (south of mouth of Port San Antonio)

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au; Mo
Other commodities As
Ore minerals arsenopyrite; molybdenite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale B-5
Latitude 55.32497
Longitude -133.57435
Nearby scientific data Find additional scientific data near this location
Location and accuracy This well known propect is along the shoreline about 0.2 mile northwest of triangulation station 'San Antonio.' It is about 0.9 mile north-northeast of Thimble Cove and about 0.4 mile south-southeast of the northwest corner of section 33, T. 75 S., R. 78 E.

Geologic setting

Geologic description

This deposit is exposed for about 600 feet just above the shoreline (Roehm, 1936 [PE 119-3]; Smith, 1942 [B 926-C]; Twenhofel and others, 1946). Silurian or Ordovician argillite and quartzite of the Descon Formation are intruded by a Cretaceous granodiorite pluton (Eberlein and others, 1983; Brew, 1996). The contact is marked by several hundred, generally parallel, quartz veins and veinlets 1 to 3 inches thick in the granodiorite. Molybdenite, arsenopyrite, pyrite, and pyrrhotite occur in the veins, along vein selvages, and along fractures in the granodiorite. The granite is silicified.
The property was originally staked from 1927 to 1930 and four holes were drilled in 1932 (Roehm, 1936 [PE 119-3]). Smith (1942 [B 926-C]), citing an unpublished report on the 1932 drilling, estimated that the deposit contains about 100,000 tons of mineralized rock that averages 0.276 percent molybdenum. The property was drilled again in 1943, and Twenhofel and others (1946) estimated that the deposit contains less than 0.05 percent molybdenum. Several descriptions of the deposit mention high gold values and Roehm (1936 [PE 119-3]) states that core samples from the holes drilled in 1932 contained an average of $3.20 in gold per ton (at $20.67 per ounce?).
Geologic map unit (-133.576034000499, 55.3246231331757)
Mineral deposit model Gold and molybdenum in quartz veinlets in the periphery of a granodiorite pluton.
Age of mineralization Deposit is probably related to emplacement of the granodiorite host rock.
Alteration of deposit Granodiorite host rock is silicified.

Production and reserves

Workings or exploration The deposit is well exposed just above the shoreline and 4 holes were diamond drilled in 1932. There was additional diamond drilling in 1943.
Indication of production None
Reserve estimates Smith (1942 [B 926-C]), citing an unpublished report on the 1932 drilling, estimated that the deposit contains about 100,000 tons of mineralized rock that averages 0.276 percent molybdenum. The property was drilled again in 1943, and Twenhofel and others (1946) estimated that the deposit contains less than 0.05 percent molybdenum. Several descriptions of the deposit mention high gold values, and Roehm (1936 [PE 119-3]) states that core samples from the holes drilled in 1932 contained an average of $3.20 in gold per ton (at $20.67 per ounce?).

References

MRDS Number A010155

References

Reporters D.J. Grybeck (Applied Geology)
Last report date 5/1/2004