Columbium-, Rare-earth-element-, and Thorium-Bearing Veins Near Salmon Bay, Southeastern Alaska.
In 1984 and 1985, the Bureau of Mines investigated radioactive carbonate veins near Salmon Bay, southeastern Alaska, for concentrations of columbium and associated metals. The veins cut units of graywacke, conglomerate, argillite, and limestone and range in width from less than 1 in to greater than 10 ft and have a length ranging from less than 100 to greater than 1,000 ft. Mineralogy of the veins is complex and includes thorite, the rare-earth-element (ree) minerals monazite, parisite, and bastnaesite, and a columbium mineral that is speculated to be columbite. Gangue minerals include ankerite, dolomite, siderite, quartz, and albite. More than 70 veins were sampled, but only 3 contained elevated metal concentrations along a significant strike length. The three veins contain a combined indicated resource of 340,000 lb cb, 2.2 Mmlb ree, and 11,700 lb th in 763,000 st of rock. The columbium resource is contained in one of the three veins that averages 840 ppm cb over a width of 3.4 Ft and a length of 1,200 ft. These resources are small compared to columbium, ree, and thorium resources elsewhere in the world.