Distribution of Gold, Platinum, Palladium, and Silver in Selected Portions of the Bohemia Basin Deposits, Southeast Alaska (With an Appendix Section on Mirror Harbor).
This report presents results of a 1982 Bureau of Mines examination of the Bohemia Basin nickel-copper-cobalt deposits, located on the southeastern portion of Yakobi Island, to determine the potential for platinum-group metals, gold, and silver. The deposits are thought to be magmatic segregations in a zoned composite stock. Demonstrated resources, accessible by open pit mining, are 15.1 million tons averaging 0.37% Nickel, 0.22% Copper, and 0.02% Cobalt. Bureau examination consisted of sampling surface outcrops, adits, and pits; and analysis of selected diamond drill hole samples for platinum-group metals, gold, and silver. Sixty samples were collected from surface outcrops and analyzed, and 185 samples from 5 diamond drill holes were analyzed. The highest gold, platinum, palladium, and silver values from the analysis of 245 surface and drill hole samples were 0.01 Oz/ton gold, 0.006 Oz/ton platinum, 0.004 Oz/ton palladium, and 0.157 Oz/ton silver; 94 of the 185 drill hole samples were analyzed for iridium, osmium, rhodium, and ruthenium, and none was detected. In general, most of the precious metal values were confined to the nickel-copper ore zones, with the highest values often coinciding with the highest nickel-copper values. Precious metals, except silver, are concentrated with copper and are potential low-grade metallurgical byproducts.