Freegold

Prospect, Undetermined

Commodities and mineralogy

Main commodities Ag; Au
Ore minerals chalcopyrite; gold; pyrite
Gangue minerals calcite; chlorite; quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale C-1
Latitude 55.65657
Longitude -132.00463
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Freegold prospect is the name used most frequently for what is labeled the 'Bert Lide Mine' on the USGS 1;63,360-scale topographic map. (The correct spelling is Bert Libe, who was involved with many of the properties in the area, including this one.) The prospect is about 0.1 mile north of the center of section 1, T. 72 S., R. 87 E. The location is accurate.

Geologic setting

Geologic description

The Freegold prospect was discovered in 1903 and in early reports was included with the Gold Standard Group (Wright and Wright, 1908). According to Roehm (1938 [PE 120-5]), it emerged as a separate prospect in about 1932. Shortly thereafter the Freegold tunnel was started and reached a length of 1,470 feet. Several of the veins on the property have been traced on the surface in numerous pits and trenches.
The mineralization is in shear zones that contain lenses, stringers, and pods of quartz. The host rocks are folded and faulted greenstone and greenschist. The two major mineralized structures are the Rodgers and the Bugge veins. In addition to the Freegold tunnel, there are two short adits on the property, and several smaller quartz veins are exposed in surface pits. Pyrite, and minor chalcopyrite and free gold occur both in the quartz veins and in the adjacent schist and greenstone. The rocks in the area consist of metamorphosed andesite, basalt, agglomerate, and tuff, and minor flysch, shale, and phyllite. Eberlein and others (1983) and Brew (1996) consider them to be Paleozoic or Mesozoic in age; Gehrels and Berg (1992) tentatively mapped them as Jurassic or Cretaceous.
The Rodgers vein was exposed in open cuts for 800 feet. The vein is 6 inches to 3 feet thick and lenticular. Small quartz veins project from the main vein and their intersections with it are notably rich. Fine needles of tourmaline occur in the quartz. Roehm (1938 [PE 120-5]) channel sampled the Rodgers vein for 150 feet on the surface; the samples contained about $14 per ton in gold (at $35 per ounce?).
The Freegold tunnel was driven to intersect the Bugge vein, but about 250 feet from the portal, the tunnel crossed another mineralized shear zone with quartz lenses. Roehm's cross-section indicates that it is about 30 feet thick. His channel samples across 7 feet of this zone contained about $14 per ton in gold (at $35 per ounce?). Bittenbender and others (1993) and Maas and others (1995) sampled in the Freegold tunnel. The weighted average of their samples along 65 feet of mineralization in the tunnel is 2,056 parts per billion gold. A select sample across 30 inches contained 17.31 parts per million (ppm) gold and 7.7 ppm silver.
Geologic map unit (-132.006314193712, 55.6562074963485)
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The quartz veins cut country rocks that may be as young as Cretaceous or as old as Paleozoic.

Production and reserves

Workings or exploration The workings consist of a 1,470-foot tunnel, two short adits, and numerous trenches and open pits.
Indication of production None
Reserve estimates None.
Production notes Apparently none.

References

References

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