The U.S. Geological Survey investigation of the mineralresource potential of Glacier Bay National Monument was made during the summer of 1966 at the request of the National Park Service for its use in planning future development of the monument. The most important results of field tests and laboratory analyses are herein summarized. Background on the geography, geology, and study methods used is given in the "Introduction." The chief metallic commodities of potential economic importance are copper, molybdenum, nickel, gold, silver, titanium, and iron. A few other metals might constitute byproducts or form deposits in some favorable areas that are as yet unexplored or concealed. The belt of Tertiary sedimentary rocks that borders the Gulf of Alaska and probably occurs offshore is a possible host for petroleum, but the potential is low. The economic potential for nonmetallic deposits known in the monument, such as coal, limestone, and dolomite, is minimal because of their low grade, impurities, cheaper availability elsewhere, and other limiting factors. The deposits considered to have the best economic potential include eight that were previously known and seven that were found during our investigations. The previously known deposits are the Nunatak molybdenum prospect; the Brady Glacier nickel-copper prospect; titanium, iron, and copper deposits associated with the layered mafic intrusive rocks of the Fairweather Range; the Alaska Chief copper prospect; gold-and ilmenite-bearing beach placers north and south of Lituya Bay; the Margerie copper prospect; and gold lodes in the Reid Inlet area and at the Sandy Cove prospect (fig. 1). The most attractive deposits found during our investigations include a copper-molybdenum deposit in the Bruce Hills; veins and altered zones north of White Glacier; base-metal lodes near Mount Brack; and copper deposits south of Rendu Glacier, near Gable Mountain, east of Dundas Bay, and west of Tarr Inlet (fig. 1). The previously known deposits are described in the order of their probable economic potential. The Nunatak molybdenum prospect and the Brady Glacier nickel-copper prospect are those most likely to be developed in the near future. The deposits of potential significance that we found cannot be ranked without additional data, and, at this stage, are considered to have about the same potential. They are all partly or largely covered by snow, ice, or surficial deposits, and satisfactory appraisals of their configurations and grades require physical exploration. These newly found deposits are of interest because of their inferred sizes, their grades, and the possibility that concealed parts of some deposit may be larger and richer than is apparent from surface examination. These deposits would be regarded as exploration possibilities by most mining companies, but remoteness and difficult access [Data from U.S. Weather Bureau, 1937-66] Precipitation (inches) Month Cape Spencer Gustavus Temivsrature (degrees Fahrenheit) Cape