Windy Pass

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Fe; Mo
Other commodities Ag; As; Au; Sb; Zn
Ore minerals arsenopyrite; chalcopyrite; molybdenite; pyrite
Gangue minerals epidote; diopside; garnet; magnetite; phlogopite

Geographic location

Quadrangle map, 1:250,000-scale MD
Quadrangle map, 1:63,360-scale C-3
Latitude 63.675
Longitude -154.061
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Windy Pass Skarn prospect is situated on a north-facing spur, overlooking a prominent southern tributary of Browns Fork of the Sulukna River at an elevation of 2,280 feet in the southeast corner of Section 17, T. 21 S., R. 25 E., of the Kateel River Meridian. The reporter visited the site in 1992.

Geologic setting

Geologic description

The Windy Pass Cu-Mo-(Au)-Fe skarn prospect is associated with a small, Late Cretaceous, quartz monzonite stock that has intruded Paleozoic limestone probably equivalent to the Novi Mountain Formation (Dutro and Patton, 1982). The main mineralized area is about 200 feet by 3,000 feet (61 m by 914 m) in size. Two types of skarn are identified: (1) zones of sulfides, diopside, plagioclase, and orthoclase in endoskarn; and (2) zones of chalcopyrite, molybdenite, magnetite, phlogopite, garnet, and epidote in exoskarn within the marble front (DiMarchi and others, 1992).
Chalcopyrite is the main ore mineral. Molybdenite is locally abundant. Pyrite locally contains gold values. Copper and molybdenum mainly occur in exoskarn; gold values appear to be in late stage quartz veins. Windy Pass Prospect is inferred to be Late Cretaceous, based on isotopic age dating of the quartz monzonite pluton (Moll and others, 1981).
DiMarchi and others (1992, 1994) reported values as high as 0.27 ounces/ton (8.4 ppm) gold in quartz veins, 0.25 percent copper in exoskarn, and 650 ppm molybdenum in exoskarn. Clautice and others (1993) reported grades as high as 0.61 percent copper, 359 ppm molybdenum, 3,160 ppb gold, 0.23 percent zinc, 0.43 percent arsenic, 236 ppm antimony, and 310 ppm tungsten, mainly exoskarn zones.
Geologic map unit (-154.063353342873, 63.6744150003342)
Mineral deposit model Copper skarn deposits (Cox and Singer, 1986; model 18b).
Mineral deposit model number 18b
Age of mineralization Windy Pass Prospect is inferred to be Late Cretaceous, based on isotopic age of quartz monzonite (Moll and others, 1981).
Alteration of deposit Sericite-chlorite in intrusion.

Production and reserves

Workings or exploration
The Windy Pass Cu-Mo-(Au)-Fe skarn prospect was first reported in the literature as a result of AMRAP investigations in the Medfra quadrangle (Patton and others, 1980; Patton and Moll, 1983). Work by Central Alaska Gold Company from 1991 to 1994 (DiMarchi and others, 1992, 1994) mapped, sampled and conducted ground geophysical surveys of the deposit. No drilling has taken place.
DiMarchi and others (1992, 1994) reported values as high as 0.27 ounces/ton (8.4 ppm) gold (in quartz veins), 0.25 percent copper (in exoskarn), and 650 ppm molybdenum (in exoskarn). Clautice and others (1993) reported grades as high as 0.61 percent copper, 359 ppm molybdenum, 3,160 ppb gold, 0.23 percent zinc, 0.43 percent arsenic, 236 ppm antimony, and 310 ppm tungsten from mainly exoskarn zones.
Indication of production None
Reserve estimates None reported.

Additional comments

See Nixon Fork Mine (MD062). The Windy Pass prospect is on land selected or owned by Doyon Ltd. For additional information, contact Doyon Ltd. at 210 1st Ave., Fairbanks, Alaska 99701.

References