Coffee Dome

Prospect, Active

Commodities and mineralogy

Main commodities Au; Bi; Te
Other commodities Cu; Pb; Sb; Zn
Ore minerals arsenopyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0957
Longitude -147.0827
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Coffee Dome prospect is on a large block of claims that cover about 16 square miles. However, most of the known mineralization is in an elongate north-trending area about 0.8 mile long and 0.3 mile wide near the center of section 11, T. 2 N., R. 3 E. The coordinates are at about the center of this area, about 2 miles east of Coffee Dome. The location is accurate.

Geologic setting

Geologic description

In early 2010, the Coffee Dome prospect was being explored by International Tower Hill Mines, Ltd. (2008) who staked the property from 2004 to 2006. Through 2006, the work on the property was mainly stream sediment and soil geochemical surveys and some sampling of surface mineralization. The property was first identified from anomalous gold, tellurium, and bismuth geochemical anomalies and mineralized samples collected at the surface. The mineralized samples consist of banded quartz veins 10 to 30 cm thick with scorodite and occasionally arsenopyrite. During 2007, International Tower Hill (2007) dug several trenches over the main target area that exposed veins with grades of up to 168 grams of gold per tonne and high silver, arsenic, antimony, bismuth, and tellurium. Soil surveys defined two large areas anomalous in gold that are thought to reflect a large gold system over 3 kilometers long and 1 kilometer wide. They consider the deposit analogous to the Pogo mine (BD033) and probably close to an intrusive source. The rocks in the area consist mainly of middle to early Paleozoic and(or) Late? Proterozoic quartz and pelitic schist of the Yukon-Tanana Upland (Wilson and others, 1998).
In 2009, International Tower Hill Mines (2009) drilled 5 holes on the Coffee Dome project. The holes targeted a northeast-trending structural zone that is marked at the surface by resistivity and soil-geochemistry anomalies. Multiple thick zones of low-grade gold mineralization were cut. Notable intercepts were 17 meters with 0.3 gram of gold per tonne and 22 meters with 0.21 gram of gold per tonne. Few sulfides were seen in the holes.
Geologic map unit (-147.085147675402, 65.0952849482649)
Mineral deposit model Arsenopyrite-gold-quartz veins with tellurium and bismuth.
Alteration of deposit No data.

Production and reserves

Workings or exploration In early 2010, the Coffee Dome prospect was being explored by International Tower Hill Mines, Ltd. (2008) who staked the property from 2004 to 2006. Through 2006, the work on the property was mainly stream sediment and soil geochemical surveys and some sampling of surface mineralization. During 2007, International Tower Hill (2007) dug several trenches that exposed mineralization and they extended their soil surveys. They drilled 5 holes in 2009.
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

The claims that cover the Coffee Dome prospect are both State of Alaska mining claims and land leased from the University of Alaska; as of 2007, most of the known mineralization is on the University of Alaska lands.

References

References

International Tower Hill Mines, Ltd., 2007, Trenching intersects high-grade gold veins on Coffee Dome project, Alaska: http://www.ithmines.com/s/NewsReleases.asp?ReportID=274816&_Type=News-Releases&_Title=Trenching-Intersects-High-Grade-Gold-Veins-on-Coffee-Dome-Project-Alaska (News release, November 29, 2007.
International Tower Hill Mines, Ltd., 2008 (Coffee Dome), http://ith.pubco.net/s/CoffeeDome.asp (as of March 4, 2008).
International Tower Hill Mines Ltd., 2009; ITH's Coffee Dome drilling intersects gold system 17 kilometers east of Fort Knox Mine, Alaska: http://www.ithmines.com/s/NewsReleases.asp?ReportID=375183&_Type=News-Releases&_Title=ITHs-Coffee-Dome-Drilling-Intersects-Gold-System-17-Kilometres-East-of-Fort.. (News release, December 4, 2009).
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/2/2010