1. Maps showing distribution of selected minerals in the nonmagnetic heavy-mineral fraction of stream-sediment samples, Medfra quadrangle, Alaska Yale Public content 1993. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Alaska and Medfra Region.