Yellow Pine/Stibnite Mining District

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area District outline from USMIN location polygon ID00048.
Identified resources Indicated resources of antimony and gold; past production of antimony, gold, silver, and tungsten.
Production District produced intermittently from 1932 through 1992. Yellow Pine mine (1938-1991): 856,189 stu WO3, 40,257 short tons Sb, 479,517 troy oz Au, and 1,756,928 troy oz Ag; Hangars Flats (1928-1938): 67 stu WO3, 3,758 short tons Sb, 51,610 troy oz Au and 181,863 troy oz Ag (Becker and others, 2019); Meadow Creek mine (1932-1937): 24, 500 metric tons at 2.136% Sb.
Status Past mining; exploration and permitting (2021) for Stibnite Gold project (formerly known as Golden Meadows project) (Becker and others, 2019), an open pit gold-antimony mine with reclamation. Final EIS due out near end of 2021 by Payette National Forest.
Estimated resources Stibnite Gold Project: Combined Indicated Mineral Resources:115.2 million short tons (Mst) or 104.5 million metric tonnes (Mt) grading 0.048 troy ounces per short ton (oz/st) Au or 1.63 grams per metric tonne (g/t) Au, 0.077 oz/st (2.65 g/t) Ag, and 0.07% Sb; Aggregate Indicated Mineral Resources: 5.46 million oz (Moz) Au, 8.90 Moz Ag, and 155.2 million pounds (Mlbs) Sb; Combined Probable Mineral Reserves: 98.07 Mst (88.96 Mt) grading 0.047 oz/st (1.60 g/t) Au, 0.071 oz/st (2.43 g/t) Ag, and 0.07% Sb; Total contained metal in the Probable Mineral Reserves: 4.58 Moz Au, 6.96 Moz Ag, and 137.0 Mlbs Sb. Four deposits combined also contain additional Inferred Mineral Resources of 10.8 Mst (9.8 Mt) grading 0.032 oz/st (1.10 g/t) Au, 0.049 oz/st (1.67 g/t) Ag, and 0.04% Sb that is not utilized in the prefeasibility study and Combined Inferred Mineral Resources 347 koz Au, 523 koz Ag, and 9.5 Mlbs Sb. (Becker and others, 2019).
Geologic maps Stewart and others (2016), scale 1:24,000; White (1940), scale 1:9,700.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Early Cretaceous metasedimentary strata and Idaho batholith rocks.
Deposits Yellow Pine mine (MRDS dep_id: 10217607; USMIN site ID: ID00001).
Evidence from mineral occurrences MRDS; USMIN.
Geochemical evidence See King and others (1994); Curtin and others (1974); Baldwin and Etheridge (2019); Etheridge (2015).
Geophysical evidence Unknown.
Evidence from other sources Becker and others (2019).
Comments From Wintzler and others (2022): The sequence of hydrothermal mineralizing events in the district starts with: 1) disseminated Au mineralization deposited from 70 to 56 Ma, associated with sulfidation and potassium metasomatism (Orogenic mineral system); 2) W deposition in scheelite veins and breccias that crosscut disseminated Au mineralization in granodiorite (Porphyry Co-Mo-Au mineral system); 3) formation of epithermal quartz veins with Au and Ag at 51.9 to 51.2 Ma; and 4) Sb mineralization in stibnite veins that crosscut older disseminated gold and tungsten mineralization (both Meteoric convection system, with Low sulfidation gold-silver and Low sulfidation antimony deposit types, respectively.
Cover thickness and description Exposed at the surface.
Authors Virginia S. Gillerman, Reed S. Lewis, Christopher A. Tate, Albert H. Hofstra.
New data needs Additional geology, petrography, geochemistry and geochronology to better see how antimony fits into deposit and district. Easier to do as mining progresses with collaboration with industry, lidar.
Geologic mapping and modeling needs 1:24,000 scale geologic mapping.
Geophysical survey and modeling needs High resolution, Rank 1 aeromagnetic and aeroradiometric coverage.
Digital elevation data needs Lidar incomplete.