Unnamed (along Right Fork)

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Au
Other commodities As; Sb
Ore minerals arsenopyrite; galena; gold; hematite; marcasite; pyrite; pyrrhotite; sphalerite; stibnite
Gangue minerals ankerite; calcite; dolomite; quartz

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale C-1
Latitude 67.5109
Longitude -150.1533
Nearby scientific data Find additional scientific data near this location
Location and accuracy The best exposed mineralization at this site is just southwest of 'Friday the 13th Pup', an informal name given to the small tributary to Right Fork in the northeast corner of section 14, T. 31 N., R 12 W. The mineralization then continues down Right Fork to Vermont Creek. The location is accurate.

Geologic setting

Geologic description

Maddren (1913) first identified quartz veins and veinlets along joint surfaces in bedrock on upper Right Fork, noted that at least one of the veins contained sulfides as well as specks and flakes of free gold. The best mineralization exposed at this site is just southwest of 'Friday the 13th Pup', a small tributary to Right Fork in the northeast quarter of section 13, T. 31 N., R 12 W. (Eden, 2000; Kurtak and others, 2002).
Numerous thin quartz veins cut interbedded phyllite and schist of the Upper Devonian Beaucoup Formation (Dillon and others, 1986). Eighteen veins spaced at about 5 foot intervals, occur in one 100-foot-wide exposure of the phyllite near Friday the 13th Pup. The veins average about 0.5 inch thick; they generally strike about N60W and dip 75SW. The veins consist of coarse, white quartz, calcite, ankerite and dolomite, 1-2 percent pyrite, and sparse arsenopyrite, galena, hematite, marcasite, pyrrhotite, sphalerite, and stibnite. Visible gold occurs in some of these veins, mostly along their margins. A sample of a vein with visible gold contained 17.8 parts per million (ppm) gold Other veins contain 415 parts per billion (ppb) to 63.56 ppm gold, 126 to 3,802 ppm arsenic, and 7 to 748 ppm antimony. Samples of phyllite with minor pyrite in the vicinity of the veins contained 13 to 38 ppb gold. The phyllite along Right Fork from Friday the 13th Pup down to Vermont Creek is cut by similar veins that contained up to 815 ppb gold, 1,137 ppm copper, and 1,065 ppm arsenic. A cobble-size boulder of quartz with gold and 1 percent stibnite, presumably from a local source, was found by local placer miners in Right Fork (Dillon, 1982).
Geologic map unit (-150.156052069851, 67.5104760283849)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Devonian or younger based on the age of the host rocks.
Alteration of deposit The phyllite that hosts the thin quartz veins apparently is not altered.

Production and reserves

Workings or exploration The thin gold-quartz veins in the bedrock along Right Fork have been recognized since at least 1913 and have repeatedly been sampled, most recently by Kurtak and others (2002).
Indication of production None
Reserve estimates None.
Production notes None.

References