Platinum placers were discovered in 1926 in a small area south of Goodnews Bay, in southwestern Alaska. Beginning in 1927, the placers were worked for 7 years by small-scale mining methods; in later years dragline excavators and a dredge were utilized. These deposits are important, not only because they are of high grade but because they are the only commercial source of platinum metals in the United States. The platinum metals of these deposits are contained mainly in two alloys intergrown in a pseudoeutectic fabric. The major alloy is mainly platinum, with a small amount of iridium, still smaller amounts of rhodium and palladium, and probably some osmium and ruthenium. Under certain assumptions, the tenor of platinum metals in the dunite can be roughly approximated. Utilizing two totally different methods of computation, the mean tenor has been estimated to lie between 0. 19 and 0. 27 grain of platinum metals per cubic yard of dunite, or 0. 014 to 0. 023 gram per stere. No large low-grade deposits of commercial value are likely to be found, but it is possible that some small high-grade concentrations occur.
|Publication Subtype||USGS Numbered Series|
|Title||Platinum deposits of the Goodnews Bay District, Alaska|
|Series title||Professional Paper|
|Publisher||U.S. Government Printing Office|
|Other Geospatial||Goodnews Bay|
|Google Analytic Metrics||Metrics page|