Abstract: The tungsten deposits of the Nightingale district are just within the western border of Pershing County, Nev., and in the Nightingale or Truckee Range, which lies east of Winnemucca Lake. The Tertiary volcanic rocks of the district rest unconformably upon intrusive granodiorite and steeply dipping metamorphosed limestones and slates of unknown age. The tungsten deposits are of the contact-metamorphic type: The ore consists of scheelite bearing tactite, a dark silicate rock that was formed by metamorphism of limestone at the granodiorite contact. Scheelite (calcium tungstate) is the only valuable mineral. The gangue minerals are epidote, quartz, pyroxene, garnet, calcite, tremolite, molybdenite, pyrite, pyrrhotite, chalcopyrite, arsenopyrite, apatite, and sphene. The bodies of tactite are generally tabular, and they extend downward steeply, because both the limestones and the granodiorite contact dip vertically or nearly so. The largest tactite body of the district is at the Nightingale mine; it attains a maximum thickness of 60 feet and is nearly a thousand feet long, but only for part of its length is it thick enough and rich enough to be potentially minable. That it continues downward below the mine workings, which extend to a depth of 128 feet, is shown by nine drill …

From introduction: It is the purpose of this bulletin to combine the results obtained by the USGS parties that have visited the region, together with the information derived from a study of specimens of tin ores and associated minerals recently brought from the York region by outside parties.

From introduction: Lode and placer deposits of massive topaz rock were discovered near the old Brewer gold mine in northwestern Chesterfield County, S. C., in 1935. Preliminary tests have shown that this rock can be used in the manufacture of refractory ware and as a source of mullite, thus augmenting supplies of kyanite that have been coming from India.

From introduction: The growing economic importance of the Carrville district, Trinity County, California merits notice, and it is hoped that this brief report will direct attention toward it, to the end that mining in general may be benefited.

From abstract: Scheelite ore bodies occur at widely separated localities in the Sierra Nevada near Bishop, Calif. The scheelite is found in altered sedimentary rocks at or near the contact between granitic rocks and limestones that are partly changed to silicate rocks composed largely of garnet. Mineralization was closely connected with the intrusion of the granite, the latest of the varied intrusives that make up the rocks of the Sierra Nevada.

From preface: This report satisfies the demand of the public for reliable information and to gather data which should be of use in planning further geologic work in Nevada.

From abstract: To help the mining industry of Alaska and to assist in the development of the mineral resources of the Territory have been the prime motives of the Geological Survey's investigations in Alaska during the past 35 years, in which nearly one half of the Territory has been covered by its reconnaissance and exploratory surveys. It was natural, therefore, that the Alaska Railroad, when it undertook intensive consideration of the problem of finding tonnage that would increase its revenues, should look to the Geological Survey to supply technical information as to the known mineral deposits along its route and to indicate what might be done to stimulate a larger production of minerals and induce further mining developments and prospecting that would utilize its service.

From introduction: This report is a brief preliminary study of the mineral resources of a portion of the Piedmont region.

From introduction: This report focuses on the placer geology of individual creeks; mining, history of the area, high terrace gravels, and the gold source of the Fortymile River area in Alaska.

From introduction: The presentation of a yearly record of the Alaska mineral industry is a continuing service that has been rendered by the Geological Survey from almost the earliest years of extensive mining in Alaska, and the present report, for 1938, is the thirty-fifth of this series. 2 Such a record, especially when supplemented by the statistics for the preceding years, not only affords an authoritative summary of current 'and past conditions but also indicates trends that are of significance in suggesting the lines along which future developments of the industry are likely to proceed. These reports therefore serve miners, prospectors, and businessmen concerned with Alaska affairs as useful historical records, statements of contemporary conditions, and starting points on which some conjectures concerning future operations may be predicated.

From Introduction: "The presentation of a yearly record of the Alaska mineral industry is a continuing service that has been rendered by the Geological Survey from almost the earliest years of extensive mining in Alaska, and the present report for 1939, is the thirty-sixth of this series.These reports therefore serve miners, prospectors, and businessmen concerned with Alaska affairs as useful historical records, statements of contemporary conditions, and starting points on which some conjectures concerning future operations may be predicated."

From abstract: Pt 1. The present work seems to confirm the genetic theory previously published, namely that [Illinois Cave in Rock] deposits were formed by ascending solutions. These solutions probably followed minor fissures that connected below with larger fissures, which in turn probably connected with a major fault zone. It is believed that where such minor fissures extended upward only to the shale or other impervious cap rock, or were greatly reduced in size where they penetrated such beds, the solutions spread laterally along the contact and along the limestone beds beneath it and replaced the limestone. Pt 2. This report is a presentation of the results of an electrical-resistivity survey conducted in the fluorspar-bearing areas of Hardin County, Ill., principally during the field seasons of 1934 and 1935.

From introduction: From introduction: The present report upon the work of this field season is accompanied by topographic and geologic maps of the vicinity of Juneau, and of a mainland strip extending approximately 200 miles along the coast.