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At least 73 records · Page 4Linked to original sources
USGS1999

Stratigraphic framework and heavy minerals of the continental shelf of Onslow and Long Bays, North Carolina

One hundred fourteen vibracores from the Atlantic continental shelf offshore of southeastern North Carolina were opened, described, and processed over several contract years (years 6-9) of the Minerals Management Service-Association of American State Geologists Continental Margins program. Reports for years 9 and 10 of the program compiled the results of the work and assembled the data for release as an interactive CD-ROM report, respectively. The continental shelf of Onslow and Long Bays consists predominantly of outcropping Cretaceous through late Tertiary geologic units. Nearshore these units are covered and incised by late Tertiary and Quaternary units. From oldest to youngest, formally recognized geologic units mapped as part of this study are the Late Cretaceous Peedee Formation-a muddy, fine- to medium-grained quartz sand with trace amounts of glauconite and phosphate; the Paleocene Beaufort Formation-a muddy, fine- to medium-grained glauconitic quartz sand with locally occurring turritelid-mold biosparrudite; the middle Eocene Castle Hayne Formation-a sandy bryozoan biomicrudite and biosparrudite; the Oligocene River Bend Formation-a sandy molluscan-mold biosparrudite; and the Miocene Pungo River Formation-a medium-grained, poorly sorted slightly shelly phosphatic sand. Informal units include a very widespread, unnamed fine- to very fine grained, well-sorted, dolomitic muddy quartz sand that is biostratigraphically equivalent to the Oligocene River Bend Formation; several large valley-fill lithosomes composed of biomicrudite, biomicrite, and biosparrudite of Plio/Pleistocene age; muddy, shelly sands and silty clays of Pliocene, Pleistocene, or mixed Plio/Pleistocene age; and loose, slightly shelly, medium- to coarse-grained sands assigned a Holocene age. Heavy minerals (SG > 2.96) comprise an average of 0.54 wt% (on a bulk-sample basis) of the sediments in 306 samples derived from the 114 vibracores. Heavy-mineral content ranges from <0.01 to 3.69 wt%. The economic heavy mineral content (EHM = ilmenite + zircon + rutile + aluminosilicates + leucoxene [altered ilmenite] + monazite) of the bulk samples averages 0.26 wt% in a range of <0.01-1.70 wt%. As a percentage of the heavy-mineral concentrate, the average EHM value is 45.78% in a range of 0.27-68.60%. The distribution of heavy minerals offshore of southeastern North Carolina is controlled by the lithostratigraphic framework. The unnamed Oligocene sand unit has the highest heavy-mineral content, averaging 0.86 wt% on a bulk-sample basis. The remaining geologic units and their heavy-mineral content (in decreasing order of abundance) are Beaufort (0.64%), Holocene sand (0.60%), Plio-Pleistocene muddy sand and silty clay (0.59%), Peedee (0.42%), River Bend (0.34%), Plio-Pleistocene carbonate (0.12%), and Castle Hayne (0.08%). The heavy-mineral assemblage is fairly consistent throughout the different units. Significantly smaller percentages of heavy minerals correlate with increased amounts of CaCO 3 in the sediments. The sediments analyzed in this study have significantly lower overall heavy-mineral content, as well as lower EHM content than sediments that are known to host commercially important heavy-mineral deposits in the southeastern United States. The potential for economic deposits of heavy minerals in the area of this study, therefore, appears to be limited.

Marine Georesources and Geotechnology↗
USGS2017

Assessment of critical minerals: Updated application of an early-warning screening methodology

Increasing reliance on non-renewable mineral resources reinforces the need for identifying potential supply constraints before they occur. The US National Science and Technology Council recently released a report that outlines a methodology for screening potentially critical minerals based on three indicators: supply risk ( R ), production growth ( G ), and market dynamics ( M ). This early-warning screening was initially applied to 78 minerals across the years 1996 to 2013 and identified a subset of minerals as “potentially critical” based on the geometric average of these indicators—designated as criticality potential ( C ). In this study, the screening methodology has been updated to include data for 2014, as well as to incorporate revisions and modifications to the data, where applicable. Overall, C declined in 2014 for the majority of minerals examined largely due to decreases in production concentration and price volatility. However, the results vary considerably across minerals, with some minerals, such as gallium, recording increases for all three indicators. In addition to assessing magnitudinal changes, this analysis also examines the significance of the change relative to historical variation for each mineral. For example, although mined nickel’s R declined modestly in 2014 in comparison to that of other minerals, it was by far the largest annual change recorded for mined nickel across all years examined and is attributable to Indonesia’s ban on the export of unprocessed minerals. Based on the 2014 results, 20 minerals with the highest C values have been identified for further study including the rare earths, gallium, germanium, rhodium, tantalum, and tungsten.

Mineral Economics↗
USGS1983

Application of total-count aeroradiometric maps to the exploration for heavy-mineral deposits in the coastal plain of Virginia, with a section on field-spectrometer-data reduction

Total-count contoured aeroradiometric maps for the Coastal Plain of Virginia were used in an effort to locate economic heavy-mineral placer deposits. The principle behind this approach is that heavy- mineral suites commonly contain radioactive minerals that, if the concentration of heavy minerals is exposed at or within inches of the surface, enable the deposit to be located by use of airborne instruments because of its radiometric contrast with the host sediment. Detailed and regional geologic maps, soil maps, land-use and land- cover maps, information on fertilizer use, and ground-spectrometer data were used to study aeroradiometric anomalies for efficient exploration. Aeroradiometric anomalies in the Coastal Plain of Virginia have three general causes. First, the most intense anomalies are associated with cultural features, such as roads made of granitic material. Second, most anomalies of high to intermediate intensity are associated with land used for agricultural purposes and evidently are caused by applications of radioactive fertilizer. Third, anomalies of intermediate to low intensity are associated with heavy-mineral deposits. Results of this study show that aeroradiometric anomalies associated with heavy-mineral accumulations in the Coastal Plain of Virginia have ground radiometric spectra in which thorium is the strongest component and uranium and potassium are lesser components. Heavy-mineral accumulations found in this study by use of the aeroradiometric data are not considered to be of economic importance, mostly because of the low percentage of economic minerals in the heavy-mineral suites and also because of other factors such as the very fine grained nature of the host sediments and competing land use.

Virginia↗
USGS2013

Book review: Economic geology: Principles and practice: Metals, minerals, coal and hydrocarbons—Introduction to formation and sustainable exploitation of mineral deposits

This volume, available in both hardcover and paperback, is an English translation of the fifth edition of the German language text Mineralische und Energie-Rohstoffe. The book provides an extensive overview of natural resources and societal issues associated with extracting raw materials. The comprehensive list of raw materials discussed includes metals, industrial minerals, coal, and hydrocarbons. The book is divided into four parts: (1) “Metalliferous ore deposits,” (2) “Nonmetallic minerals and rocks,” (3) “Practice of economic geology,” and (4) “Fossil energy raw materials—coal, oil, and gas.” These sections are bound by a brief introduction and an extensive list of up-to-date references as well as an index. Each chapter begins with a concise synopsis and concludes with a summary that contains useful suggestions for additional reading. All figures are grayscale images and line drawings; however, several have been grouped together and reproduced as color plates. Also included is a companion website ( www.wiley.com/go/pohl/geology ) that contains additional resources, such as digital copies of figures, tables, and an expanded index, all available for download in easy-to-use formats. Economic Geology: Principles and Practice: Metals, Minerals, Coal and Hydrocarbons—Introduction to Formation and Sustainable Exploitation of Mineral Deposits. Walter l. Pohl. 2011. Wiley-Blackwell. Pp. 663. ISBN 978-1-4443-3663-4 (paperback).

Economic Geology↗
USGS2017

Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply

Summary Mineral commodities are vital for economic growth, improving the quality of life, providing for national defense, and the overall functioning of modern society. Minerals are being used in larger quantities than ever before and in an increasingly diverse range of applications. With the increasing demand for a considerably more diverse suite of mineral commodities has come renewed recognition that competition and conflict over mineral resources can pose significant risks to the manufacturing industries that depend on them. In addition, production of many mineral commodities has become concentrated in relatively few countries (for example, tungsten, rare-earth elements, and antimony in China; niobium in Brazil; and platinum-group elements in South Africa and Russia), thus increasing the risk for supply disruption owing to political, social, or other factors. At the same time, an increasing awareness of and sensitivity to potential environmental and health issues caused by the mining and processing of many mineral commodities may place additional restrictions on mineral supplies. These factors have led a number of Governments, including the Government of the United States, to attempt to identify those mineral commodities that are viewed as most “critical” to the national economy and (or) security if supplies should be curtailed. This book presents resource and geologic information on the following 23 mineral commodities currently among those viewed as important to the national economy and national security of the United States: antimony (Sb), barite (barium, Ba), beryllium (Be), cobalt (Co), fluorite or fluorspar (fluorine, F), gallium (Ga), germanium (Ge), graphite (carbon, C), hafnium (Hf), indium (In), lithium (Li), manganese (Mn), niobium (Nb), platinum-group elements (PGE), rare-earth elements (REE), rhenium (Re), selenium (Se), tantalum (Ta), tellurium (Te), tin (Sn), titanium (Ti), vanadium (V), and zirconium (Zr). For a number of these commodities—for example, graphite, manganese, niobium, and tantalum—the United States is currently wholly dependent on imports to meet its needs. The first two chapters (A and B) deal with general information pertinent to the study of mineral resources. Chapters C through V describe individual mineral commodities and include an overview of current uses of the commodity, identified resources and their distribution nationally and globally, the state of current geologic knowledge, the potential for finding additional deposits nationally and globally, and geoenvironmental issues that may be related to the production and uses of the commodity. These chapters are updates of the commodity chapters published in 1973 in U.S. Geological Survey Professional Paper 820, “United States Mineral Resources.”

Professional Paper↗
USGS2019

Resource Assessment Economic Filter (RAEF)—A graphical user interface supporting implementation of simple engineering mine cost analyses of quantitative mineral resource assessment simulations

Economic evaluations of undiscovered mineral resources provide important context in which to consider the results of quantitative mineral resource assessments. The U.S. Geological Survey economic analysis method uses a simple engineering cost model approach developed by the U.S. Bureau of Mines that applies mine and mill engineering cost equations to simulated undiscovered deposits. The important characteristics of these deposits are derived from Monte Carlo simulations that combine probabilistic estimates of undiscovered deposits that might occur in a study area and a grade-tonnage model defined for a specific deposit type. This report describes the Resource Assessment Economic Filter (RAEF), a graphical user interface (GUI) tool that applies a set of mine cost equations to the deposits under consideration. RAEF, which is written in the open-source statistical programming language R, is an easy-to-use tool to apply user-defined mine, mill, and study area parameters to simulated deposits. For a given deposit type, it estimates the undiscovered resources that might be economic to extract. In addition, RAEF provides a series of graphical, tabular, and statistical summaries that document the results of the economic filter analysis.

Techniques and Methods↗
USGS2004

A hydrogeologic model of stratiform copper mineralization in the Midcontinent Rift System, Northern Michigan, USA

This paper presents a suite of two-dimensional mathematical models of basin-scale groundwater flow and heat transfer for the middle Proterozoic Midcontinent Rift System. The models were used to assess the hydrodynamic driving mechanisms responsible for main-stage stratiform copper mineralization of the basal Nonesuch Formation during the post-volcanic/pre-compressional phase of basin evolution. Results suggest that compaction of the basal aquifer (Copper Harbor Formation), in response to mechanical loading during deposition of the overlying Freda Sandstone, generated a pulse of marginward-directed, compaction-driven discharge of cupriferous brines from within the basal aquifer. The timing of this pulse is consistent with the radiometric dates for the timing of mineralization. Thinning of the basal aquifer near White Pine, Michigan, enhanced stratiform copper mineralization. Focused upward leakage of copper-laden brines into the lowermost facies of the pyrite-rich Nonesuch Formation resulted in copper sulfide mineralization in response to a change in oxidation state. Economic-grade mineralization within the White Pine ore district is a consequence of intense focusing of compaction-driven discharge, and corresponding amplification of leakage into the basal Nonesuch Formation, where the basal aquifer thins dramatically atop the Porcupine Mountains volcanic structure. Equilibrium geochemical modeling and mass-balance calculations support this conclusion. We also assessed whether topography and density-driven flow systems could have caused ore genesis at White Pine. Topography-driven flow associated with the Ottawan orogeny was discounted because it post-dates main-stage ore genesis and because recent seismic interpretations of basin inversion indicates that basin geometry would not be conductive to ore genesis. Density-driven flow systems did not produce focused discharge in the vicinity of the White Pine ore district.

Michigan↗
USGS1975

Heavy minerals in stream sands of the southern Hazara District, Pakistan

The areal distribution of heavy minerals in 99 samples from stream sands in the southern Hazara District, West Pakistan, indicates that the metamorphic grade of the rocks in the area increases toward the northwest. Minerals of potential economic value in the heavy-mineral samples include scheelite from the Oghi-Batgram-Battal area and hematite from the Galdanian area. The total weight of magnetite sand grains transported down the Indus River past Darband is calculated to be about 200,000 tons per year, a quantity which may be of economic value. Radioactive minerals are not present in any of the samples in sufficient quantity to be of economic importance.

Hazara District↗
USGS2024

Understanding key mineral supply chain dynamics using economics-informed material flow analysis and Bayesian optimization

The low-carbon energy transition requires significant increases in production for many mineral commodities. Understanding demand, technological requirements, and prices associated with this production increase requires understanding the supply chain dynamics of many minerals simultaneously, and via a consistent framework. A generalized economics-informed material flow method, global materials modeling using Bayesian optimization, captures the market dynamics of key mineral commodities. The method relies only on a limited set of widely available historical data as input, enabling quantification of economic relationships (elasticities) for supply chain components where data are sparse, and relationships cannot be obtained via traditional statistical approaches. Building upon established material flow analysis (MFA) and economic modeling techniques, Bayesian optimization was applied to fit an economics-informed MFA model to global historical demand, supply, and price for aluminum, copper, gold, lead, nickel, silver, iron, tin, and zinc. This approach enables estimates for the evolution of ore grades, mine costs, refining charges, sector-specific demand, and scrap collection for each commodity. Economic relationships were quantified and compared with a database compiled from the literature, including 1333 values from 213 analyses across 65 publications. Discrepancies in methods and limited coverage make use of these parameters in modeling efforts difficult. This work provides a single, homogeneous, probabilistic approach to identifying economic relationships across mineral supply chains, with uncertainty quantification, a literature database for comparison, and a modeling framework in which to use them. This article met the requirements for a Gold-Gold JIE data openness badge described at http://jie.click/badges .

Journal of Industrial Ecology↗
USGS1984

NONFUEL MINERAL RESOURCES OF THE PACIFIC EXCLUSIVE ECONOMIC ZONE.

The Pacific Exclusive Economic Zone contains a variety of hard mineral resources. Sand and gravel and their associated placer deposits of heavy minerals are the most likely to be developed in the near future, but offshore and deep water deposits of phosphorite, abyssal manganese nodules, ferromanganese crusts enriched in cobalt, and massive sulfide deposits all represent future resources. The distribution, extent, and formation of these deposits are poorly understood and will be clarified only with additional exploration, framework geologic mapping, and study of the processes by which these resources form. It is pointed out that the initial discovery of most hard-mineral resources in the EEZ was made during routine scientific marine-geologic surveys aimed at understanding the framework geology and geologic processes of an offshore region.

Conference Paper↗
USGS1998

Carolina slate belt gold deposits in Virginia, North Carolina, South Carolina, and Georgia

The Southeastern United States, in particular, the Carolina slate belt of Virginia, North Carolina, South Carolina, and Georgia, has been an important region of mineral production (fig. 1). This region is thought to have major potential for containing large undiscovered deposits of gold and silver, as well as copper, lead, zinc, molybdenum, and tin. Gold production from the major mines (Haile, Brewer, Ridgeway, and Barite Hill) in South Carolina ranked sixth in the Nation in 1992. Despite the closing of all but one mine in 1997, the region continues to attract intense scrutiny by the mining industry. Current U.S. Geological Survey (USGS) efforts in the slate belt are led by a multidisciplinary team focused on an integrated, multistate, and multiyear project that has the potential to result in a fundamental reinterpretation of the economic geology of the region. The slate belt is considered a scientific frontier because of the rapid pace of data acquisition by the USGS, academia, and private sector geologists and because emerging concepts of its geologic evolution are controversial. Establishing the origin of the gold deposits is important, not only in guiding exploration, but for more accurate assessment of the potential for the occurrence of new deposits throughout the southern Appalachians. These efforts may result in further industry exploration that may lead to discovery of new economically viable mineral deposits, which would have a broad economic impact on the region. Another goal is to find ways to prevent human activities related to gold extraction from remobilizing toxic metals found in these deposits, which could have potential harmful effects on the environment.

Georgia, North Carolina, South Carolina, Virginia↗
USGS1978

Mineral resources of the Rincon wilderness study area, Pima County, Arizona

The Rincon wilderness study area comprises about 254 km 2 (98 mi 2 ) of the Rincon Mountains 15-30 km (10-20 mi) east of Tucson, Arizona. The area lies within the Coronado National Forest and forms a belt around the north, east, and south sides of the Saguaro National Monument (fig. 1). A mineral resource survey was made of the area in 1977 by the U.S. Geological Survey and the U.S. Bureau of Mines. This study indicates that the potential for finding metallic or nonmetallic mineral deposits, petroleum or coal or geothermal energy in the study area is low. This appraisal is based on geologic and geochemical investigations and on examination of all mineralized prospects. A geologic map was made of the area and its immediate surrounding. Chemical and spectrographic analyses were made of 1.30 stream-sediment samples and of 143 rock samples. The locations of mining claims were compiled and samples from most of the claims were assayed. There has been no recorded mineral production from within the study area. The geology of the Rincon Mountains is structurally complex. The core of the Rincon Mountains, lying mainly within the Saguaro National Monument, is underlain by igneous and metamorphic rocks chiefly of Precambrian and Tertiary ages. The study area lies on the flanks of the mountains in a terrain of sedimentary, metamorphic, and igneous rocks mainly of Precambrian through mid-Tertiary age. The rocks of this area are cut by many faults, with low-angle or bedding-parallel faults abundant. the distribution of these faulted rocks around the flanks of the Rincon Mountains is the result of a doming in the core area, the sliding of rock masses from the high part of the dome down its flanks, and to the effects of erosion. The potential for economic metallic mineral deposits is considered low because the known areas of anomalous concentrations of metals are small and the concentration of metals weak and erratic. The surface signs of mineralization are largely restricted to 4 locales in which some prospects exist (fig. 1): (1) east of Colossal Cave, southwest or the Rincon Mountains, (2) north of Happy Valley, east of the mountains, (3) between Roble and Youtcy Canyons, northeast of the mountains, and (4) near Italian Trap north of the mountains. Very little primary sulfide mineralization is present and signs of alteration are restricted to narrow zones along faults and fractures. The geochemical anomalies are weak. The sites at which anomalous values of copper, molybdenum, or silver were obtained are mainly controlled by faults. Nonmetallic mineral resources occur in deposits that are too small and too remote to be economically attractive. Sand and gravel deposits in the main drainages are similar to larger deposits that occur closer to nearby highways and cities. Limestone and marble present in some of the metamorphic rocks are too impure and too broken for use as dimension stone. Use of this marble as decorative rock is limited by remote markets. Limestone suitable for making cement is not likely to be found in large quantities within the Rincon wilderness study area. Closely spaced fractures in the granitic rocks makes them of little value for building stone.

Arizona↗
USGS1955

Ore deposits on northwestern Chichagof Island, Alaska

The area mapped includes most of northwestern Chichagof Island. The work, started in 1946, is a continuation of the geologic mapping done in the adjoining Chichagof mining district by Reed and Coats. The gold-bearing zone recognized by these writers continues through the area mapped by the writer to the northern shore of Chichagof Island. Stratified rocks ranging in age from Paleozoic through Early Cretaceous were intruded by gabbro, quartz diorite, norite-gabbro, and by younger quartz diorite. The igneous rocks from oldest to youngest are: gabbro, diorite, quartz diorite, the rocks associated with the nickel deposits, which include gabbro-norite and quartz diorite, and basalt. The diorite is believed to have been formed during Early Cretaceous time, and the gabbro is older by an unknown amount. The gabbro and diorite are believed to be, over large areas, recrystallized older rock. The oldest group of quartz diorite intrusives in places cuts the diorite and is therefore younger. The quartz diorite is minerally somewhat foliated and slightly metamorphosed. The igneous rocks associated with the nickel deposits are the youngest of the major igneous rock groups. They intruded the Cretaceous graywacke after it had been folded to essentially its present position. Gold is the most economically important mineral commodity mined to date. The Apex and El Nido are the two largest mines in the area, but some gold has been recovered from the Goldwin and Cobol properties and small amounts from some other small prospects. In addition to gold the area includes nickel-bearing deposits at Mirror Harbor on Chichagof Island and at Bohemia Basin on Yakobi Island. Copper mineralization occurs in the area north of Goulding Harbor. An attempt has been made to outline areas favorable for prospecting based on the regional geology and, on the number and kind of quartz veins found. In general the best area for prospecting appears to be on a northwest-trending zone which extends from the head Pinta Bay to the northern end of Althorp Peninsula.

Alaska↗
USGS2025

Review: The hydrogeology of critical mineral resources relevant to the energy transition

Attaining the goals of the international treaty on climate change (the Paris Agreement) will greatly increase the demand for the critical minerals required to implement clean-energy technologies. This poses both challenges and opportunities to the hydrogeologic community from several perspectives. Here, important insights that the hydrogeological sciences have to offer for mineral exploration, mineral production, and addressing environmental issues related to mining and mine decommissioning are summarized. This study focuses on copper, cobalt, lithium, and rare earths to represent the broad spectrum of critical minerals and illustrate their relevance by referring to projected demands and production rates. The current understanding of the hydrogeologic processes that form major deposits of these minerals are then summarized. Ore is defined as the naturally occurring material from which minerals of economic value can be extracted, where most ore deposits are the products of complex hydrogeologic couplings between fluid flow, heat transport, solute transport, chemical reactions, and mechanical deformation. Exploration models for the discovery of deeper, hidden deposits are potentially informed by hydrogeologic theory and hydrogeochemical processes. Hydrogeologic understanding and methods are also essential to production and recovery. Longstanding challenges are mine dewatering and (conversely) mine water supply, as well as mineral-extraction practices such as spoil heap leaching and in situ mining. New challenges arise from element extraction from subsurface brines. Finally, the quantity of water use and potential environmental impacts of mining on water quality are at the core of ‘social license’: the approval and acceptance of society to mining activities.

Hydrogeology Journal↗
USGS1978

Spectrographic and chemical analyses of whole-rock and insoluble-residue samples, Rolla 1 degree x 2 degrees quadrangle, Missouri: Drill hole no. 12

Geochemical studies of the Rolla, Mo., 1° x 2° quadrangle were begun in 1977 as a part of a joint multidisciplinary study of the quadrangle by the U.S. Geological Survey and the Division of Geology and Land Survey, Missouri Department of Natural Resources. The study is to access the mineral resource potential of the area by integrated geologic, geochemical, and geophysical studies. The geochemical work to date has been directed at the characterization of the sedimentary and igneous rocks in the quadrangle through spectrographic and chemical analyses of whole-rock samples and dilute-hydrochloric-acid insoluble-residue samples of whole rock from widely spaced drill holes. Sixty-two drill holes have been selected for study from the sample library of the Missouri Division of Geology and Land Survey. None of the holes are company confidential, none intersect economically significant mineralized ground, and only a few are located in known ore-bearing trends. The analytical results for drill hole No. 12, Missouri log numbers 12195 and 12339, are given in this report. The drill hole is located in sec. 18, T. 34 N., R. 5 W. in Reynolds County. Data of the whole-rock samples are listed in table 1, and data of the insoluble-residue samples are listed in table 2. Missouri log number, county, and location allow correlation with the stratigraphic logs on file at the Missouri Division of Geology and Land Survey in Rolla, Mo.

Missouri↗
USGS1978

Spectrographic and chemical analyses of whole-rock and insoluble-residue samples, Rolla 1 degree x 2 degrees quadrangle, Missouri: Drill hole no. 3

Geochemical studies of the Rolla, Mo., 1° x 2° quadrangle were begun in 1977 as part of a joint multidisciplinary study of the quadrangle by the U.S. Geological Survey and the Division of Geology and Land Survey, Missouri Department of Natural Resources. The study is to access the mineral resource potential of the area by integrated geologic, geochemical, and geophysical studies. The geochemical work to date has been directed at the characterization of the sedimentary and igneous rocks in the quadrangle through spectrographic and chemical analyses of whole-rock samples and dilute-hydrochloric-acid insoluble-residue samples of whole rock from widely spaced drill holes. Sixty-two drill holes have been selected for study from the sample library of the Missouri Division of Geology and Land Survey. None of the holes are company-confidential, none intersect economically significant mineralized ground, and only a few are located in known ore-bearing trends. The analytical results for drill hole No. 3, Missouri log number 18839, are given in this report. The drill hole is located in sec. 3, T. 34 N., R. 2 W., in Iron County. Data for the whole-rock samples are listed in table 1, and data for the insoluble-residue samples are listed in table 2. Missouri log number, county, and location allow correlation with the stratigraphic logs on file at the Missouri Division of Geology and Land Survey in Rolla, Mo.

Missouri↗