Unnamed Occurrence (ARDF - ID144; southwest Granite Mountain), Iditarod Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - ID144; southwest Granite Mountain)	- not defined -
Iditarod Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is about 1.4 mile southwest of the peak 2923, the top of Granite Mountain, at an elevation of about 2,300 feet. It is about 0.5 mile east-southeast of the center of section 30, T. 26 N., R. 40 W., of the Seward Meridian. The location is accurate.
Geology: This occurrence consists of a extensive zone of cassiterite-bearing, tourmaline-axinite greisen that may be a southwest extension of the similar occurrence to the northeast (ID146) (Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). Tourmaline-rich quartz porphyry and brecciated tourmaline-axinite-cemented hornfels occurs in the cupola zone of the 62.6 Ma, Granite Mountain pluton (Miller and Bundtzen, 1994). Bundtzen and Miller (1997) identified disseminated cassiterite in one sample; however, no sulfides or sulfosalts were observed. Grab samples of mineralization contained up to 300 parts per million (ppm) tin, 7,000 parts per billion (ppb) silver, 500 ppm lead, 54 ppm antimony, 100 ppm arsenic, 54 ppm bismuth, and more than 2,000 ppm boron (McGimsey and others, 1988).
Workings: Samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in 1984 (McGimsey and others, 1988).
Age: Undated; probably related to the nearby Granite Mountain pluton that has an age of 62.6 Ma (Bundtzen and Miller,1997).
Alteration: Development of tourmaline-axinite greisen.

Commodities (Major) - Ag, Sn; (Minor) - As, B, Bi, Pb, Sb
Development Status: None
Deposit Model: Sn-polymetallic deposit (Cox and Singer, 1986; model 20b).

Other Databases

Link to USGS - Alaska:	ID144

Other Regions, Features and Areas containing this locality

References