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At least 595 records · Page 33Linked to original sources

Barite: a case study of import reliance on an essential material for oil and gas exploration and development drilling

Global dependence on a limited number of countries for specific mineral commodities could lead to sudden supply disruptions for the United States, and barite is one such commodity. Analyses of barite supply amounts and sources for the United States are demonstrative of mineral commodities on which the country is import reliant. Mineral commodity trade flows can be analyzed more easily than import reliances for commodities in which U.S. domestic demand is primarily met by materials contained within manufactured products, as with the rare-earth elements in cellular phones and computers. Barite plays an essential role as a weighting material in drilling muds used in oil and gas drilling, primarily to prevent the explosive release of gas and oil during drilling. The Nation’s efforts to become more energy independent are based largely on the domestic oil and gas industry’s ability to explore and develop onshore and offshore fuel deposits. These activities include increased efforts by the United States to locate and recover oil and gas within unconventional deposits, such as those in the Bakken, Eagle Ford, and Marcellus Formations, using advanced drilling technologies. Domestic barite production was about 670,000 metric tons (t) in 2012, equivalent to about 20 percent of the domestic drilling industry’s barite demand. Mine production for the United States in 2012 was about one-third of what was produced in 1980. In 2012, barite imported from China was approximately 2.2 million t and comprised about 77 percent of total barite imports and about 70 percent of the barite used in domestic drilling. Barite from India (14 percent), Morocco (6 percent) and Mexico (2 percent) comprised the bulk of the remaining total import balance; drilling applications consumed nearly all barite imported from these three countries.

Scientific Investigations Report↗

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↗

Trace metals related to historical iron smelting at Hopewell Furnace National Historic Site, Berks and Chester Counties, Pennsylvania

Iron ore containing elevated concentrations of trace metals was smelted at Hopewell Furnace during its 113 years of operation (1771-1883). The ore used at Hopewell Furnace was obtained from iron mines within 5 miles of the furnace. The iron-ore deposits were formed about 200 million years ago and contain abundant magnetite, the primary iron mineral, and accessory minerals enriched in arsenic, cobalt, copper, lead, and other metals. Hopewell Furnace, built by Mark Bird during 1770-71, was one of the last of the charcoal-burning, cold-blast iron furnaces operated in Pennsylvania. The most productive years for Hopewell Furnace were from 1830 to 1837. Castings were the most profitable product, especially the popular Hopewell Stove. More than 80,000 stoves were cast at Hopewell, which produced as many as 23 types and sizes of cooking and heating stoves. Beginning in the 1840s, the iron industry shifted to large-scale, steam-driven coke and anthracite furnaces. Independent rural enterprises like Hopewell could no longer compete when the iron and steel industries consolidated in urban manufacturing centers. The furnace ceased operation in 1883 (Kurjack, 1954). The U.S. Geological Survey (USGS), in cooperation with the National Park Service, completed a study at Hopewell Furnace National Historic Site (NHS) in Berks and Chester Counties, Pennsylvania, to determine the fate of toxic trace metals, such as arsenic, cobalt, and lead, released into the environment during historical iron-smelting operations. The results of the study, conducted during 2008-10, are presented in this fact sheet.

Pennsylvania↗

Arsenic in Chinese coals: Distribution, modes of occurrence, and environmental effects

Arsenic, one of the most hazardous elements occurring in coals, can be released to the environment during coal processing and combustion. Based on the available literature and published results obtained in our laboratory, the content, distribution and the modes of occurrence of As in Chinese coals, and its environmental and impacts are reviewed in this article. With the 4763 sets of data (from the literature) rearranged, the arithmetic mean As concentration of each province and weighted mean As concentration of the entire country (using the expected coal reserves as the weighting factor) were calculated. The weighted mean As concentration in Chinese coals is 3.18 mg/kg, with As concentration increasing from northern China to southern China. The As concentration in coal varies with coal-forming ages and coal ranks. Arsenic has several modes of occurrence in coals. According to results obtained by other studies and our own experiments, As is mainly associated with mineral matter (such as pyrite and other sulfide minerals) in coals, although a significant amount of arsenic is associated with organic matter. The accumulation of As in coal is controlled by many geological factors during coal-forming processes, including plant decomposition, sedimentary environments, and epigenetic hydrothermal activity. During the combustion of coal, As is released to the air, water, and soil, causing serious environmental pollution. More than 45% of the coal consumed in China is utilized by power plants, and it is estimated that nearly 522 tonnes, 21 tonnes and 252 tonnes of As are emitted into the atmosphere by industries, residential buildings and coal-fired power plants, respectively, every year.

Article↗

Quality of water in alluvial aquifers in eastern Iowa

The goal of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program is to assess the status and trends in the quality of the Nation's surface and ground water, and to better understand the natural and human factors affecting water quality. The Eastern Iowa Basins study unit encompasses an area of about 50,500 square kilometers (19,500 square miles) in eastern Iowa and southern Minnesota and is one of 59 study units in the NAWQA program. Land-use studies are an important component of the NAWQA program, and are designed to assess the concentration and distribution of water-quality constituents in recently recharged ground water associated with the most significant land use and hydrogeologic settings within a study unit. The focus of the land-use study in the Eastern Iowa Basins study unit is agricultural and urban land uses and alluvial aquifers. Agriculture is the dominant land use in the study unit. Urban areas, although not extensive, represent important potential source areas of contaminants associated with residential, commercial, and industrial activities. Alluvial aquifers are present throughout much of the study unit, and constitute a major ground-water supply that is susceptible to contamination from land-use activities. Ground-water samples were collected from monitoring wells at 31 agricultural and 30 urban sites in the Eastern Iowa Basins study unit during June-August 1997 to evaluate the effects of land use and hydrogeology on the water quality of alluvial aquifers. Calcium, magnesium, and bicarbonate were the dominant ions in most samples and were likely derived from solution of carbonate minerals (calcite and dolomite) present in alluvial detrital deposits. Tritium-based ages indicate ground water was most likely recharged after the 1950's at all but one sampling site. Agricultural and urban land-use areas have remained relatively stable in the study area since the 1950's, therefore the effects of current land use should be reflected in ground water sampled during this study. Sodium and chloride concentrations were significantly higher in samples from urban areas, where roads are more numerous and road salts may be more frequently applied, than in agricultural areas. Nitrate was detected in 94 percent of samples from agricultural areas and 77 percent of samples from urban areas. Nitrate concentrations were significantly higher in agricultural areas than in urban areas and exceeded the U.S. Environmental Protection Agency maximum contaminant level for drinking water (10 milligrams per liter as N) in 39 percent of samples from agricultural areas. Nitrate concentrations in samples from urban areas did not exceed the maximum contaminant level. Greater usage of fertilizers in agricultural areas most likely contributes to higher nitrate concentrations in samples from those areas. Pesticides were detected in 84 percent of samples from agricultural areas and 70 percent from urban areas. Atrazine and metolachlor were the most frequently detected pesticides in samples from agricultural areas; atrazine and prometon were the most frequently detected pesticides in samples from urban areas. None of the pesticide concentrations exceeded U.S. Environmental Protection Agency maximum contaminant levels or lifetime health advisories for drinking water. Pesticide degradates were detected in 94 percent of samples from agricultural areas and 53 percent from urban areas. Metolachlor ethane sulfonic acid and deethylatrazine were the most frequently detected metabolites in samples from agricultural areas; metolachlor ethane sulfonic acid and alachlor ethane sulfonic acid were the most frequently detected degradates in samples from urban areas. Total degradate concentrations were significantly higher in samples from agricultural areas than in samples from urban areas. Total pesticide concentrations (parent compounds) tended to be higher in samples from agricultural areas; however, this difference was not statistically significant. Degradates constituted the major portion of the total residue concentration in the alluvial aquifer. Volatile organic compounds were detected in 40 percent of samples from urban areas and 10 percent from agricultural areas. Methyl tert-butyl ether was the most commonly detected volatile organic compound and was present in 23 percent of samples from urban areas. Elevated concentrations (greater than 30 micrograms per liter) of methyl tert-butyl ether and BTEX compounds (benzene, toluene, ethylbenzene, and xylene) in two samples from urban areas suggest the possible presence of point-source gasoline leaks or spills. Factors other than land use may contribute to observed differences in water quality between and within agricultural and urban areas. Nitrate, atrazine, deethylatrazine, and deisopropylatrazine concentrations were significantly higher in shallow wells with sample intervals nearer the water table and in wells with thinner cumulative clay thickness above the sample intervals, suggesting that longer flow paths allow for greater residence time and increase opportunities for sorbtion, degradation, and dispersion which may contribute to decreases in nutrient and pesticide concentrations with depth. Nitrogen speciation was influenced by redox conditions. Nitrate concentrations were significantly higher in ground water with dissolved-oxygen concentrations in excess of 0.5 milligrams per liter. Ammonia concentrations were higher in ground water with dissolved-oxygen concentrations of 0.5 milligrams per liter or less, however, this relation was not statistically significant. The amount of available organic matter may limit denitrification rates. Elevated nitrate concentrations (greater than 2.0 mg/L) were significantly related to lower dissolved organic carbon concentrations in water samples from both agricultural and urban areas. A similar relation between nitrate concentrations (in water) and organic carbon concentrations (in aquifer material) also was observed but was not statistically significant.

Iowa↗

Map showing high-purity silica sand of Middle Ordovician age in the Midwestern states

Certain quartz sands of Middle Ordovician age in the Midwestern States are well known for their purity and are exploited for a wide variety of industrial uses. The principal Middle Ordovician formations containing high-purity sands are the St. Peter Sandstone which crops out extensively from Minnesota to Arkansas; the Everton Formation principally of Arkansas; and the Oil Creek, McLish, and Tulip Creek Formations (all of the Simpson Group) of Oklahoma. The St. Peter and sandy beds in the other formations are commonly called "sandstones," but a more appropriate term is "sands" for in most fresh exposures they are completely uncemented or very weakly cemented. On exposure to air, uncemented sands usually become "case hardened" where evaporating ground water precipitates mineral matter at the surface; but this is a surficial effect. This report summarizes the available information on the extent of exposures, range of grain size, and chemical composition of the Middle Ordovician sands.

Arkansas;Illinois;Iowa;Minnesota;Missouri;Oklahoma↗

Map showing areas with potential for talc deposits in the Gravelly, Greenhorn, and Ruby Ranges and the Henrys Lake Mountains of southwestern Montana

For the last several years, Montana has been the leading talc producing state in the United States (U.S. Geological Survey, 1996). For example, in 1992 Montana supplied about 40 percent of the U.S. mine production of talc (Virta, 1992). All of this production has come from the large deposits of high purity talc in the southwestern part of the state. All Montana talc is currently (1997) extracted from four mines, each within the study area of this map—the open pit operations of the Treasure State, Regal, and Yellowstone mines and the underground operation of the Beaverhead mine (see map numbers 1-4 on list and map to the left). The related mineral chlorite is mined at the Antler mine, located nearby, but outside of the study area in the Highland Mountains. Montana talc has at least two market advantages: (1) some deposits are very large and near surface, allowing economic mining by open pit methods; and (2) the deposits are of high purity and lack tremolite or other amphibole mineral contaminants (such as absestos) that occur in some other talc-rich deposits. Talc from southwest Montana is used in ceramics, paint, paper, plastics, cosmetics, rubber, roofing, flooring, caulking, and agricultural applications. The talc is also used in the processes of recycling paper and plastics. Talc was first discovered in the early 1900's at the present site of the Yellowstone mine (Perry, 1948, p. 9). Modest production began in 1942 from shallow pits and adits, supplying steatite (massive, compact, high-purity) talc that was used to make ceramic insulators. The southwest Montana talc industry grew to become a significant part of the region's economy; this history is described by Perry (1948), Olson (1976), and Berg (1997). Exploration and development are likely to continue for the foreseeable future for several reasons: (1) mines are active in the area at present and an infrastructure for talc processing exists; (2) large changes in domestic and export talc markets are not expected in the next few years based on recent market trends (Virta, 1997); (3) the talc of this region is especially pure and asbestos-free; and (4) except for potential ground stabilization problems and land disturbance associated with largescale open pit mining, no significant environmental impacts are associated with talc mining.

Montana↗

Summary appraisals of the Nation's ground-water resources; Souris-Red-Rainy region

A broad-perspective analysis of the ground-water resources and present and possible future water development and management in the Souris-Red-Rainy Region is presented. The region includes the basins of the Souris River within Montana and North Dakota; the Red River of the North in South Dakota, North Dakota, and Minnesota; and the Rainy River within Minnesota. The region includes 59,645 square miles, mostly in North Dakota and Minnesota. The terrain is relatively flat, but ranges in altitude from 2,541 to 750 feet. Annual average precipitation ranges from 14 inches in the west to 28 inches in the east and about 75 percent of it is rain. The mean annual snow fall ranges from 32 inches in the west to 64 inches in the east. Temperatures range from -55° to 118°F (-48.3° to 47.8°C). Irrigation is needed at least part of the time to assure crop production, particularly in the western part of the region. Sand and gravel deposits in the drift form the most important fresh-water aquifers. Other aquifers are found in at least parts of the region in the Precambrian, Paleozoic, Cretaceous, and Tertiary rocks. The potentiometric surface in the bedrock generally decreases in altitude toward the Red River of the North, indicating that the general direction of ground-water movement is toward the river. Ground-water with less than 3,000 milligrams per liter dissolved solids is available throughout the region. Ground water with less than 1,000 milligrams per liter occurs in most of the region east of the Red River of the North and in most of the shallow aquifers west of the river. The total volume of water available from storage having less than 3,000 milligrams per liter dissolved solids is estimated to be 5 x 10 8 acre-feet. In addition to the fresh and slightly saline water, the region has abundant highly mineralized water that can be considered as a resource. Yields of wells in individual bedrock aquifers are generally less than 100 gallons per minute but locally yields may be as much as 500 gallons per minute and more. Yields in drift aquifers are frequently less than 100 gallons per minute but range from 5 to 1,000 gallons per minute. In a few places outwash yields more than 1,000 gallons per minute. Ground water is the sole or a primary source of water supply in much of the region, including supplies for irrigation, domestic and livestock, municipal, and industrial needs. Reportedly, the potential irrigation development is 1,550,000 acres, as compared with 50,200 acres in 1975. Both ground- and surface-water supplies would be required to meet these demands. Rural domestic and livestock water supplies are derived almost entirely from ground-water sources. Smaller communities and towns generally rely on ground water, and the cities and industries use ground water, surface water, or both. The municipalities using surface water generally depend upon reservoir storage. Water quality rather than quantity is the greater water-supply problem for many communities in the region. Increased demands on both ground-water and surface-water supplies likely will be made in the future. Storage of surface water in the ground-water reservoirs during times of surplus for withdrawal during times of scarcity would aid in meeting these demands. The surplus (flood) water is of better chemical quality than underlying ground water in parts of the western half of the region. Fresh water could be stored in saline- or fresh-water aquifers, and pumped out later, as needed. Thus, the ground-water reservoirs have a definite present and potential role in water management. To understand the hydrologic system for management purposes there is a need to determine more adequately the geologic and hydrologic characteristics of existing aquifers and the location of new aquifers. Also, as pumping and other stresses on any part of the hydrologic system affect other parts of the system, monitoring programs ideally should be started and maintained to detect changes and determine effects of the stresses. Many alternatives are available for managing water in the region. Some of these are operational and others are undergoing research. Adequate hydrologic information is needed to aid in solving problems of water supply, use and pollution.

Minnesota, Montana, North Dakota, South Dakota↗

Summary appraisals of the nation's ground-water resources – Souris-Red-Rainy region

A broad-perspective analysis of the ground-water resources and present and possible future water development and management in the Souris-Red-Rainy Region is presented. The region includes the basins of the Souris River within Montana and North Dakota; the Red River of the North in South Dakota, North Dakota, and Minnesota; and the Rainy River within Minnesota. The region includes 59,645 square miles, mostly in North Dakota and Minnesota. The terrain is relatively flat, but ranges in altitude from 2,541 to 750 feet. Annual average precipitation ranges from 14 inches in the west to 28 inches in the east and about 75 percent of it is rain. The mean annual snowfall ranges from 32 inches in the west to 64 inches in the east. Temperatures range from -55° to 118° F (-48.3° to 47.8° C). Irrigation is needed at least part of the time to assure crop production, particularly in the western part of the region. Sand and gravel deposits in the drift form the most important freshwater aquifers. Other aquifers are found in at least parts of the region in the Precambrian, Paleozoic, Cretaceous, and Tertiary rocks. The potentiometric surface in the bedrock aquifers generally decreases in altitude toward the Red River of the North, indicating that the general direction of ground-water movement is toward the river. Ground water with less than 3,000 milligrams per liter dissolved solids is available throughout the region. Ground water with less than 1,000 milligrams per liter occurs in most of the region east of the Red River of the North and in most of the shallow aquifers west of the river. The total volume of water available from storage having less than 3,000 milligrams per liter dissolved solids is estimated to be 5x10 8 acre-feet. In addition to the fresh and slightly saline water, the region has abundant highly mineralized water that can be considered as a resource. Yields of wells in individual bedrock aquifers are generally less than 100 gallons per minute but locally yields may be as much as 500 gallons per minute and more. Yields in drift aquifers are frequently less than 100 gallons per minute but range from 5 to 1,000 gallons per minute. In a few places outwash yields more than 1,000 gallons per minute. Ground water is the sole or a primary source of water supply in much of the region, including supplies for irrigation, domestic and livestock, municipal, and industrial needs. Reportedly, the potential irrigation development is 1,550,000 acres, as compared with 50,200 acres in 1975. Both ground- and surface-water supplies would be required to meet these demands. Rural domestic and livestock water supplies are derived almost entirely from ground-water sources. Smaller communities and towns generally rely on ground water, and the cities and industries use ground water, surface water, or both. The municipalities using surface water generally depend upon reservoir storage. Water quality rather than quantity is the greater water-supply problem for many communities in the region. Increased demands on both ground-water and surface-water supplies likely will be made in the future. Storage of surface water in the ground-water reservoirs during times of surplus for withdrawal during times of scarcity would aid in meeting these demands. The surplus (flood) water is of better chemical quality than underlying ground water in parts of the western half of the region. Freshwater could be stored in saline- or freshwater aquifers, and pumped out later, as needed. Thus, the ground-water reservoirs have a definite present and potential role in water management. To understand the hydrologic system for management purposes there is a need to determine more adequately the geologic and hydrologic characteristics of existing aquifers and the location of new aquifers. Also, as pumping and other stresses on any part of the hydrologic system affect other parts of the system, monitoring programs ideally should be started and maintained to detect changes and determine effects of the stresses. Many alternatives are available for managing water in the region. Some of these are operational and others are undergoing research. Adequate hydrologic information is needed to aid in solving problems of water supply, use, and pollution.

Minnesota, Montana, North Dakota, South Dakota↗

Germanium: giving microelectronics an efficiency boost

Introduction Germanium is a rare element but is present in trace quantities in most rock types because of its affinity for iron- and organic-bearing materials. The average germanium content of the Earth is about 14 parts per million, but the majority of germanium resides within the Earth’s core (37 parts per million) while the Earth’s crust contains only about 1.5 parts per million. Germanium does not occur as a native metal in nature, but about 30 different germanium minerals are known to exist. In refined form, it is grayish-white and metallic in appearance. Germanium is a semiconducting metalloid with electrical properties between those of a metal and an insulator. Germanium was discovered in the late 1800s within silver ore at a mine near Freiberg, Germany. The German chemist who described the element, Clemens Winkler, named it germanium, after his native country. More than half a century elapsed before its first commercial use after World War II, when Karl Lark-Horovitz from Purdue University discovered its properties as a semiconductor. Today germanium is commonly used in commercial, industrial, and military applications. Germanium is an essentially nontoxic element, with the exception of only a few compounds. However, if dissolved concentrations in drinking water are as high as one or more parts per million chronic diseases may occur.

Fact Sheet↗

Geohydrology of the High Plains Aquifer, western Kansas

The High Plains aquifer underlies 174,050 sq mi of eight states (Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming) and contains approximately 3.3 billion acre-ft of water in storage. Saturated thicknesses within the aquifer are as great as 600 ft near the southern border of southwest Kansas. The aquifer is replenished primarily by infiltration from precipitation. Average precipitation at the Garden City Experiment Station is 18.93 in/yr. Groundwater flow is generally from west to east under unconfined conditions. Hydraulic connection with subcropping consolidated aquifers allows ground water to flow vertically in minor quantities. The aquifer is depleted primarily by irrigation. Hydraulic conductivity estimates from 1,612 lithologic logs had an average value of 75 ft/day, with a standard deviation of 35 ft/day. Specific yields estimated from the same lithologic logs had a mean of 0.17 and a standard deviation of 0.047. Water from the High Plains aquifer in Kansas generally is suitable for human and animal consumption and irrigation of crops. Typically, it is a calcium bicarbonate type water, with concentrations of total dissolved solids ranging from 250 to 500 mg/L. The quality of water in the aquifer deteriorates toward the east due to mixing with recharge water containing dissolved minerals leached from the overlying soil and unsaturated zones and mineralized water from adjacent bedrock units. The simulated water budget for the steady state model of predevelopment (pre-1950) conditions in the High Plains aquifer in northwest Kansas showed that annual recharge to the aquifer from infiltration of precipitation was 87,000 acre-ft/yr and from boundary inflow, 21,000 acre-ft/yr. Annual discharge from the aquifer was 108,000 acre-ft/yr, including 81,000 acre-ft/yr from leakage to streams, 23,000 acre-ft from outflow at the boundaries of the aquifer, and 4,000 acre-ft from municipal and industrial pumpage. (Lantz-PTT)

Water-Resources Investigations Report↗

Nephelometric determination of fluorine

Fluorine in minerals may be determined with the nephelometer to about 1 per cent of the fluorine. The determination is made on an aliquot of the sodium chloride solution of the fluorine, obtained by the Berzelius method of extraction. The fluorine is precipitated as colloidal calcium fluoride in alcoholic solution, gelatin serving as a protective colloid. Arsenates, sulfates, and phosphates, which interfere with the determination, must be removed.

Industrial And Engineering Chemistry Analytical Ed↗

Mineral commodity profiles: nitrogen

Overview -- Nitrogen (N) is an essential element of life and a part of all animal and plant proteins. As a part of the DNA and RNA molecules, nitrogen is an essential constituent of each individual's genetic blueprint. As an essential element in the chlorophyll molecule, nitrogen is vital to a plant's ability to photosynthesize. Some crop plants, such as alfalfa, peas, peanuts, and soybeans, can convert atmospheric nitrogen into a usable form by a process referred to as 'fixation.' Most of the nitrogen that is available for crop production, however, comes from decomposing animal and plant waste or from commercially produced fertilizers. Commercial fertilizers contain nitrogen in the form of ammonium and/or nitrate or in a form that is quickly converted to the ammonium or nitrate form once the fertilizer is applied to the soil. Ammonia is generally the source of nitrogen in fertilizers. Anhydrous ammonia is commercially produced by reacting nitrogen with hydrogen under high temperatures and pressures. The source of nitrogen is the atmosphere, which is almost 80 percent nitrogen. Hydrogen is derived from a variety of raw materials, which include water, and crude oil, coal, and natural gas hydrocarbons. Nitrogen-based fertilizers are produced from ammonia feedstocks through a variety of chemical processes. Small quantities of nitrates are produced from mineral resources principally in Chile. In 2002, anhydrous ammonia and other nitrogen materials were produced in more than 70 countries. Global ammonia production was 108 million metric tons (Mt) of contained nitrogen. With 28 percent of this total, China was the largest producer of ammonia. Asia contributed 46 percent of total world ammonia production, and countries of the former U.S.S.R. represented 13 percent. North America also produced 13 percent of the total; Western Europe, 9 percent; the Middle East, 7 percent; Central America and South America, 5 percent; Eastern Europe, 3 percent; and Africa and Oceania contributed the remaining 4 percent (International Fertilizer Industry Association, 2003b, p. 1-4). In 2002, world ammonia exports were 13.1 Mt of contained nitrogen. Trinidad and Tobago (22 percent), Russia (18 percent), Ukraine (10 percent), and Indonesia (7 percent) accounted for 57 percent of the world total. The largest importing regions were North America with 36 percent of the total followed by Western Europe with 23 percent and Asia with 22 percent (International Fertilizer Industry Association, 2003b, p. 5L-11). In 2002, world urea production was 51.4 Mt of contained nitrogen, and exports were 12.0 Mt of contained nitrogen. China and India, which were the two largest producing countries, accounted for 48 percent of world production. The United States and Canada produced about 10 percent of the total. Russia and Ukraine together accounted for 28 percent of total urea exports; Central America and South America, 27 percent; and Asia, North America, and Western Europe, 10 percent each. North America accounted for 36 percent of the total urea imports; Western Europe, 23 percent; and Asia, 22 percent (International Fertilizer Industry Association, 2003f, p. 1-15). Ammonia production capacity in North America and Western Europe is projected to decline through 2004, and capacity in other world regions is projected to increase. Fluctuating natural gas prices are mainly responsible for the capacity decline in North America. Ammonia production capacity is continuing to shift to world regions that have abundant sources of natural gas, and away from those where costs (raw material, labor, environmental compliance) are higher.

Open-File Report↗

Technologic gaps in exploration and exploitation of sub-sea mineral resources

Progress in marine hard mineral exploration and exploitation has been severely restricted by technologic gaps and the lack of discovery of deposits that can be exploited at a competitive price in the world markets. Immediate needs include improved techniques of placer drilling to permit more reliable evaluation of in situ deposits and improved systems of dredging and processing in greater depths of water and in heavier seas. New exploration techniques for locating and characterizing the subsurface deposits, and breakthroughs in low-cost methods for rapid detailed three-dimensional mapping of the seafloor relief similar to the photogrammetry breakthrough on land, would offer new incentives to industry. Advances in solution mining, in situ extraction techniques and rapid excavation with the possibilities of sub-sea entry, could eventually shift the emphasis in ocean mining from near shore placers to large-scale exploitation of deeply buried consolidated deposits.

Conference Paper↗

Tin

Tin (Sn) is one of the first metals to be used by humans. Almost without exception, tin is used as an alloy. Because of its hardening effect on copper, tin was used in bronze implements as early as 3500 B.C. The major uses of tin today are for cans and containers, construction materials, transportation materials, and solder. The predominant ore mineral of tin, by far, is cassiterite (SnO 2 ). In 2015, the world’s total estimated mine production of tin was 289,000 metric tons of contained tin. Total world reserves at the end of 2016 were estimated to be 4,700,000 metric tons. China held about 24 percent of the world’s tin reserves and accounted for 38 percent of the world’s 2015 production of tin. The proportion of scrap used in tin production is between 10 and 25 percent. Unlike many metals, tin recycling is relatively efficient, and the fraction of tin in discarded products that get recycled is greater than 50 percent. Only about 20 percent of the world’s identified tin resources occur as primary hydrothermal hard-rock veins, or lodes. These lodes contain predominantly high-temperature minerals and almost invariably occur in close association with silicic, peraluminous granites. About 80 percent of the world’s identified tin resources occur as unconsolidated secondary or placer deposits in riverbeds and valleys or on the sea floor. The largest concentration of both onshore and offshore placers is in the extensive tin belt of Southeast Asia, which stretches from China in the north, through Thailand, Burma (also referred to as Myanmar), and Malaysia, to the islands of Indonesia in the south. Furthermore, tin placers are almost always found closely allied to the granites from which they originate. Other countries with significant tin resources are Australia, Bolivia, and Brazil. Most hydrothermal tin deposits belong to what can be thought of as a superclass of porphyry-greisen deposits. The hydrothermal tin deposits are all characterized by a close spatial, temporal, and genetic association with highly differentiated, peraluminous porphyritic granite intrusions. The intrusions form pegmatites; disseminated ore; parallel or subparallel, greisen-bordered sheeted veins that either cross-cut the intrusion or are peripheral to it; skarns; and (or) limestone replacements that contain different amounts of cassiterite, molybdenite, and wolframite. The tectonic settings of tin-bearing granites are relatively well understood and of limited variety. Tin and tungsten deposits and their associated igneous rocks are found mainly in continental settings. Historically, prospecting for tin has been carried out by the time-honored methods of panning, drilling, trenching, and assaying. Geophysical and geochemical surveys have been employed to cover large areas more rapidly, isolating areas of possible tin deposits so that drilling can be more effective and less costly. Elemental concentrations and relationships of the lithophile elements, especially barium, lithium, niobium, potassium, rubidium, and zirconium, are the most reliable chemical indicators of ore-forming processes and tin-bearing potential. The average human diet includes an intake of about 10 milligrams per day of tin. Ingestion of tin in significantly greater amounts than 10 milligrams per day may lead to a stomach ache, anemia, and liver and kidney problems. Exposure to some organo-tin compounds can interfere with brain and nervous system function and, in severe cases, can cause death. Extended inhalation of tin oxide—an issue mainly for those people who work in the tin industry—results in a higher potential to develop stannosis, which is a mild disease of the lungs caused by the inhalation of tin-bearing dust. Inorganic tin is poorly absorbed by the body, and no evidence exists for the carcinogenicity of metallic tin and tin compounds in humans. Most placer tin deposits are mined by open pit and (or) dredging methods. Mining of alluvial placers in modern streambeds and riverbeds is likely to increase the amount of sediment delivered downstream. This, combined with potential diversion of rivers and streams, may negatively affect downstream ecosystems. Many of the placer deposits located in Burma, Indonesia, Malaysia, and Thailand are located offshore. Most offshore placer tin deposits are mined by dredging methods, which have the potential to negatively affect benthic, midwater, and pelagic ecosystems. In a congressionally mandated U.S. Department of Defense study of strategic minerals published in 2013, tin has the greatest shortfall amount (insufficient supply to meet demand) at \$416 million; this amount is more than twice that of antimony ($182 million), which is the strategic mineral with the next largest shortfall amount (U.S. Department of Defense, 2013). The United States imported 75 percent of its tin supply in 2015. During the period 2012–15, these imports were from, in descending order of amount imported, Peru, Indonesia, Malaysia, and Bolivia. A promising advancement concerning research into the origin of tin deposits is the recent development of a reliable method of analyzing tin isotopes in cassiterite. Although the mechanism of transport and deposition of tin is fairly well understood, the means by which tin is incorporated into the parent magma at the points of magma generation and ascent needs further investigation. Tin metallogenic provinces worldwide are well known. Consequently, any undiscovered tin deposits will likely be spatially close to known deposits or extensions of the same.

Professional Paper↗

Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 μg/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 μg/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 μg/L at pH < 7.5 regardless of geology. δ 53 Cr values in native ground-water ranged from 0.7 to 5.1‰ and values were fractionated relative to the average δ 53 Cr composition of 0‰ in the earth’s crust. Positive δ 53 Cr values of 1.2 and 2.3‰ were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. δ 53 Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing δ 53 Cr values were observed as dissolved O 2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest δ 53 Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. δ 53 Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from −0.1 to 3.2‰. Near zero δ 53 Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased δ 53 Cr values at the site. Although δ 53 Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the δ 53 Cr values in conjunction with major-ion data, and the δ 18 O and δD composition of water from wells.

Applied Geochemistry↗

Variation of lead isotopic composition and atomic weight in terrestrial materials (IUPAC Technical Report)

The isotopic composition and atomic weight of lead are variable in terrestrial materials because its three heaviest stable isotopes are stable end-products of the radioactive decay of uranium ( 238 U to 206 Pb; 235 U to 207 Pb) and thorium ( 232 Th to 208 Pb). The lightest stable isotope, 204 Pb, is primordial. These variations in isotope ratios and atomic weights provide useful information in many areas of science, including geochronology, archaeology, environmental studies, and forensic science. While elemental lead can serve as an abundant and homogeneous isotopic reference, deviations from the isotope ratios in other lead occurrences limit the accuracy with which a standard atomic weight can be given for lead. In a comprehensive review of several hundred publications and analyses of more than 8000 samples, published isotope data indicate that the lowest reported lead atomic weight of a normal terrestrial materials is 206.1462 ± 0.0028 ( k = 2), determined for a growth of the phosphate mineral monazite around a garnet relic from an Archean high-grade metamorphic terrain in north-western Scotland, which contains mostly 206 Pb and almost no 204 Pb. The highest published lead atomic weight is 207.9351 ± 0.0005 ( k = 2) for monazite from a micro-inclusion in a garnet relic, also from a high-grade metamorphic terrain in north-western Scotland, which contains almost pure radiogenic 208 Pb. When expressed as an interval, the lead atomic weight is [206.14, 207.94]. It is proposed that a value of 207.2 be adopted for the single lead atomic-weight value for education, commerce, and industry, corresponding to previously published conventional atomic-weight values.

Pure and Applied Chemistry↗

Research is needed to inform environmental management of hydrothermally inactive and extinct polymetallic sulfide (PMS) deposits

Polymetallic sulfide (PMS) deposits produced at hydrothermal vents in the deep sea are of potential interest to miners. Hydrothermally active sulfide ecosystems are valued for the extraordinary chemosynthetic communities that they support. Many countries, including Canada, Portugal, and the United States, protect vent ecosystems in their Exclusive Economic Zones. When hydrothermal activity ceases temporarily (dormancy) or permanently (extinction), the habitat and associated ecosystem change dramatically. Until recently, so-called “inactive sulfide” habitats, either dormant or extinct, received little attention from biologists. However, the need for environmental management of deep-sea mining places new imperatives for building scientific understanding of the structure and function of inactive PMS deposits. This paper calls for actions of the scientific community and the emergent seabed mining industry to i) undertake fundamental ecological descriptions and study of ecosystem functions and services associated with hydrothermally inactive PMS deposits, ii) evaluate potential environmental risks to ecosystems of inactive PMS deposits through research, and iii) identify environmental management needs that may enable mining of inactive PMS deposits. Mining of some extinct PMS deposits may have reduced environmental risk compared to other seabed mining activities, but this must be validated through scientific research on a case-by-case basis.

Marine Policy↗