A report about the Seaman volcanic center which is a composite, middle Tertiary stratovolcano in southern 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: Tin-bearing veinlets are exposed in a small area near Izenhood Ranch, 22 miles north of Battle Mountain, Nev. They occur in thick rhyolitic flows of Miocene (?) age, and wood tin, found in the gravels of arroyos that head in the surrounding rhyolite, presumably comes from -other veinlets not yet discovered. The exposed veinlets are about 20 feet in maximum length and a quarter of an inch in average thickness. Parallel and reticulating veinlets form lodes 4 to 6 feet thick and 15 or 20 feet long. Virtually no cassiterite is disseminated in the wall rock.

Abstract: This report summarizes the results of reconnaissance study of quicksilver deposits in the northwestern corner of Nevada, the northeastern corner of California, and Lake County, Oreg. made in August 1940. The Lene Pine district, Nevada, the Silvertown and Red Hawk properties in California, and the Currier and Glass Butte properties in Oregon were included. The first two of these require further development before a definite opinion as to their value can be formed. The Red Hawk mine has yielded high-grade ore, but the ore bodies so far worked are very small and scattered. The small amount of development at the recently opened Currier mine has yielded encouraging results. The deposits in the Glass Buttes are large but of such low grade that thorough sampling would be needed to determine their value. In general the region appears to warrant more attention from quicksilver prospectors than it has yet received.

From introduction: This report describes the stratigraphy and structure of the Seaman Range in southeastern Nevada, consisting of three main structural blocks that are bounded by major normal faults and adjacent valley fills.

From abstract: The Mount Grafton Wilderness Study Area (NV- 040-169) is in a remote area of the Schell Creek Range, Nevada. In 1984 and 1985 the U.S. Geological Survey and the U.S. Bureau of Mines evaluated the identified mineral resources and mineral resource potential of approximately 30,115 acres of the study area at the request of the U.S. Bureau of Land Management. The study area contains identified low-grade resources of zinc and tungsten. The study area has a low potential for oil and gas, uranium and thorium, and geothermal and clay resources.

From introduction: This report presents an evaluation of the mineral endowment (identified resources (known) and mineral resource potential (undiscovered)) of the study area and is the product of several separate studies by the USBM and the USGS.

From abstract: At the request of the U.S. Bureau of Land Management, approximately 84,165 acres of the Clover Mountains Wilderness Study Area (NV-050-139) was evaluated for mineral resources (known) and mineral resource potential (undiscovered). In this report, the area studied is referred to as "the wilderness study area" or simply "the study area;" any reference to the Clover Mountains Wilderness Study Area refers only to that part of the wilderness study area for which a mineral survey was requested by the U.S. Bureau of Land Management. The study area is located in southern Nevada, in Lincoln County, about 90 mi northeast of Las Vegas. No identified mineral resources exist inside the study area, although gold, silver, and copper resources are found immediately to the west at the Pennsylvania mine.

From abstract: Anthracite Ridge is in south-central Alaska, on the north side of the Matanuska River Valley, about 200 miles north of Seward, the coastal terminus of the Alaska Railroad. The specific object of the investigations in this field during the summer of 1931 was to collect information regarding the character and extent of the anthracite deposits. These studies were carried on in connection with similar intensive studies of deposits of other kinds of minerals throughout the country tributary to the Alaska Railroad.

Abstract: The Three Kids manganese district, in Clark County, Nev., has produced between 15,000 and 20,000 tons of ore, which contained between 30 and 40 percent manganese, 1.5 percent iron, and 12 percent silica. It is estimated that the reserves in the district aggregate about 5,500,000 tons of ore averaging about 10 percent manganese. Of this amount about 800,000 tons contains more than 20 percent manganese and 4,700,000 tons contains from 5 to 20 percent manganese. The manganese ore is a sedimentary deposit and consists of wad interbedded with lake or playa sediments belonging to the Muddy Creek formation of Pliocene (?) age. Where the manganese content is as high as 30 percent, the wad forms thick massive beds separated by thin almost barren partings. Where the content is low, the wad forms very thin lenses or small irregular blebs scattered through sandstone, or a cement for the sand grains. The zone of manganiferous beds ranges from about 10 to 75 feet in aggregate thickness, but at most places the thickness is between 25 and 40 feet.

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 …

Report describing the characteristics of manganese deposits found in White Pine County, Nevada, and geographic information about the surrounding area.

Abstract: The presence of cinnabar in the Wild Horse district, in western Lander County, Nev., has been known since about 1916, but little ore was produced until 1940. In that year and early in 1941, deposits discovered in 1939 were mined to apparent exhaustion by the Wild Horse Quicksilver Mining Co., which had produced 827 flasks at the end of April 1941. The district is underlain by moderately deformed sandstone, shale, and limestone of Lower and Middle Triassic age, locally covered by remnants of a mantle of Tertiary fanglomerate, tuff, and lava. The Triassic rocks are partly silicified, and cinnabar has been found in and near silicified rock, particularly the silicified limestone at the base of -the Middle Triassic. The ore bodies so far discovered were individually small and ill-defined, and had an average tenor of less than 0.5 percent of quicksilver. Other similar ore bodies are to be expected at moderate depths, but the cost of exploration for them may, perhaps, prove excessive.

From Introduction: "The Opalite quicksilver district includes two deposits with a considerable past production, one deposit with a small production, and one unproved prospect. These deposits are located along the circumference of a semicircular area that extends from a short distance west of McDermitt, Nev., for about 20 miles along the Oregon-Nevada State boundary. (See fig. 34). The area thus includes parts of Humboldt County, Nev., and Malheur County, Oreg.; almost the entire production has been derived from the portion in Oregon."

Abstract: The tin and copper deposits at Majuba Hill, Pershing County, Nevada are in a partly brecciated plug of Tertiary rhyolite porphyry, which is altered nearly everywhere to quartz and sericite and in some places is intensely tourmalinized. The tin mineral, cassiterite, appears to be associated with the alteration, for the single concentration of it was formed by replacement of altered breccia. Brecciated and altered rock is, however, only a general guide to potentially tin-bearing ground, and not a specific guide to ore shoots, for most of such rock appears to contain only small amounts of cassiterite, widely and unevenly distributed. The known deposit, which is exposed only underground, is at most 20 by 20 by 10 feet in size, and may contain about 12,000 pounds of metallic tin. The deposit is cut off by a normal fault, which apparently is of small displacement, and the footwall segment has not been found. The copper deposit is in the same normal fault, about 300 feet south of the earlier-formed tin deposit. From it about 4,000 tons of 12 percent copper ore was mined in 1915-18, but none has been mined since and no copper ore is now in sight.

Results of a survey of the Worthington Mountains Wilderness Study Area (NV-040-242) in Lincoln County, Nevada to determine mineral values, if any. The survey determined that metallic mineral (Cu, Pb, Zn, Au, Ag, W) resource potential within the study area is moderate, with level-B certainty, in the northernmost part, and it is low, with level-C certainty, in the remainder of the area. The report outlines the survey measurements and final results, with references and associated resource materials.

From summary: The White Rock Range Wilderness Study Area (NV-040-202/UT-040-216) is in Lincoln County, Nevada, and Beaver and Iron Counties, Utah, along the southern Nevada-Utah state line. Ursine, the town nearest to the study area, is about 15 mi (miles) southwest of the study area; the larger town of Pioche is about 30 mi southwest of the study area on Nevada Highway 322. A joint mineral resource appraisal of the 23,625 acre wilderness study area was completed in the summers of 1984 and 1985 by the U.S. Geological Survey and U.S. Bureau of Mines. The White Rock Range Wilderness Study Area has no identified mineral resources and has low mineral resource potential for metals; the potential for oil and gas, coal, and geothermal energy is also low.

From summary: During 1983 and 1984, the U.S. Geological Survey and the U.S. Bureau of Mines conducted field investigations to assess the mineral resource potential and appraise the identified resources of a part of the Far South Egans (NV-040-172) Wilderness Study Area. The area studied encompasses about 63.5 mi2 (square miles) (42,316 acres) in Lincoln and Nye Counties, Nevada, and is in the southern part of the Egan Range of east-central Nevada.

From summary: The Parsnip Peak (NV-040-206) Wilderness Study Area in Lincoln County, Nevada, is 10 mi (miles) northeast of the small mining town of Pioche. A mineral resource study of the area was completed in the summers of 1984 and 1985 by the U.S. Geological Survey and U.S. Bureau of Mines. A small area of limestone and dolomite on the western side of the wilderness study area has high mineral resource potential for arsenic, antimony, mercury, and gold. The rest of the Parsnip Peak Wilderness Study Area has low mineral resource potential for metals, oil and gas, coal, and geothermal energy.

From summary: The USGS (U.S. Geological Survey) and the USBM (U.S. Bureau of Mines) studied the mineral resource potential of 50,499 acres of the 61,137-acre Weepah Spring Wilderness Study Area (NV-040-246), Lincoln and Nye Counties, Nev., at the request of the BLM (U.S. Bureau of Land Management). In this report, the area studied is referred to as the "wilderness study area" or the "study area." Field studies of the area were conducted during summer 1984 by USBM geologists and during spring 1984 and fall 1985 by USGS geologists, geochemists, and geophysicists.

The following report focuses on the geology of the Tertiary volcanic rock formation in the Sleeper gold-silver deposit of Nevada and develops a framework for exploration and genetic models.

Proceedings of a workshop held in February 1990 called "Tertiary Stratigraphy of Highly Extended Terranes, Southern Basin and Range" at the Desert Research Center of the California State University System, Soda Springs, near Baker, California. This volume is a collection of stratigraphic data and interpretation.

The following report is the second compilation of reports describing the geology of the Basin and Range to Colorado Plateau Transition (BARCO) area.

The following report presents geochemical data results of 34 elements in 951 samples of altered and mineralized rock samples from mines, prospects, dumps, and drillholes in the Tonopah quadrangle, Nevada.