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Jane M. Hammarstrom

Publications and source records attributed to Jane M. Hammarstrom.

At least 19 recordsLinked to original sources
USGS2025

Synergy between geology and geophysics in graphite mineral resource assessment

Graphite is designated as a critical mineral by the U.S. Government due to its essential role in modern technology and its vulnerability to supply chain disruption. To evaluate domestic graphite resources, the U.S. Geological Survey (USGS) conducted two airborne electromagnetic (AEM) surveys as part of the Earth Mapping Resources Initiative (Earth MRI) over prospective areas in the southern Appalachians of Alabama and the Seward Peninsula of Alaska. These surveys aimed to refine areas of interest by revealing subsurface electrical resistivity patterns indicative of graphite-bearing rocks. The results of the AEM surveys were integrated with existing geological knowledge and supplemented by field observations to assess the likelihood of undiscovered resources in these regions. This multidisciplinary approach combined geophysical techniques with traditional geological methods, enhancing the understanding of graphite potential in areas that may have been previously overlooked. The findings from this initiative are expected to contribute significantly to the ongoing efforts to secure a reliable domestic supply of graphite, thereby reducing import reliance and supporting national interests in mineral resource management.

Conference Paper↗
USGS2023

National map of focus areas for potential critical mineral resources in the United States

Introduction The U.S. Geological Survey (USGS) launched the Earth Mapping Resources Initiative (Earth MRI) to modernize the surface and subsurface geologic mapping of the United States, with a focus on identifying areas that may have the potential to contain critical mineral resources. EarthMRI can inform strategies to ensure secure and reliable domestic critical mineral supplies for the United States as mandated by Executive Order 13817 and the Infrastructure and Jobs Act of 2021 (Public Law 117–58, 135 Stat. 529). Earth MRI is a collaborative effort between the USGS and the State geological surveys as represented by the Association of American State Geologists to identify, prioritize, and acquire new geoscience data for geographic areas, or focus areas, across the Nation that have potential to host critical mineral resources. Mapping of focus areas was based on a framework of mineral systems and their associated mineral deposit types that could possibly host critical minerals. Using readily available geologic, geophysical, geochemical, and mineral deposit data, teams of USGS scientists worked with representatives of State geological surveys in a series of workshops to outline focus areas that contain evidence of key features for one or more mineral systems. These areas can be used to guide future efforts to collect new geologic, geophysical, geochemical, and topographic data that focus on critical minerals through Earth MRI.

Fact Sheet↗
USGS2023

Critical minerals for a carbon-neutral future

The Earth Mapping Resources Initiative is filling data gaps and fostering more holistic understanding of critical mineral resources in the United States using a novel mineral systems framework.

Eos, American Geophysical Union↗
USGS2022

Focus areas for data acquisition for potential domestic resources of 13 critical minerals in the conterminous United States and Puerto Rico — Antimony, barite, beryllium, chromium, fluorspar, hafnium, helium, magnesium, manganese, potash, uranium, vanadium, and zirconium

The Earth Mapping Resources Initiative (Earth MRI) is conducted in phases to identify areas for acquiring new geologic framework data to identify potential domestic resources of the 35 mineral materials designated as critical minerals for the United States. This report describes the data sources and summary results for 13 critical minerals evaluated in the conterminous United States and Puerto Rico during phase 3 of the study (antimony, barite, beryllium, chromium, fluorspar, hafnium, helium, magnesium, manganese, potash, uranium, vanadium, and zirconium). Phases 1 and 2 of the Earth MRI addressed aluminum, cobalt, graphite, lithium, niobium, platinum-group elements (PGEs), rare earth elements (REEs), tantalum, tin, titanium, and tungsten. Critical minerals in Alaska are covered in a separate report. No focus areas for phase 3 critical minerals are delineated for Hawaii. The geologic, geochemical, topographic, and geophysical mapping provided by the Earth MRI documents geologic features that reflect the extent of individual mineral systems and provides information about critical mineral deposits that may not have been previously considered. The mineral-systems approach links critical mineral commodities to deposit types that represent the manifestations of large mineral systems. Each of the 13 critical mineral commodities for phase 3 of the Earth MRI is discussed in terms of its importance to the Nation’s economy, modes of occurrence, mineral systems, and deposit types, and is accompanied by maps and tables listing examples of focus areas in the conterminous United States and Puerto Rico. Examples of important mineral systems for this group of 13 critical minerals include basin brine path systems for barite and fluorspar, Carlin-type systems and Coeur d’Alene systems for antimony, chemical weathering and volcanogenic seafloor systems for manganese, Climax-type systems for beryllium, mafic magmatic systems for chromium, marine evaporite systems for potash and magnesium, meteoric recharge systems for uranium, petroleum systems for helium, and placer systems for zirconium and hafnium.

Open-File Report↗
USGS2022

Porphyry copper: Revisiting mineral resource assessment predictions for the Andes

A mineral resource assessment of porphyry copper deposits in the Andes Mountains of South America was done in 2005 in cooperation with geological surveys in South America. The study identified 590 million metric tons (Mt) of copper in identified resources. Continued exploration and development in the region over a 15-year period provide an opportunity to compare the predicted assessment results with new discoveries and resource growth in previously known deposits. The 2005 assessment estimated that 145 undiscovered deposits could contain a mean of 750 Mt of copper. The actual number of deposits increased (2005 to 2020) from 69 to 120 and the amount of identified copper resources increased from 590 Mt to 1600 Mt. Although most of the new deposits and copper resources are concentrated in Miocene-Pliocene and Eocene-Oligocene mineral belts, new deposits have been discovered in Jurassic and Cretaceous mineral belts. Resource growth in porphyry copper deposits known in the Andes in 2005 (1100 Mt copper) exceeds copper resources in new discoveries since 2005 (490 Mt copper) by a factor of 2.

Andes Mountains↗
USGS2022

Environmental geochemistry at Red Mountain, an unmined volcanogenic massive sulphide deposit in the Bonnifield district, Alaska Range, east-central Alaska

The unmined, pyrite-rich Red Mountain (Dry Creek) deposit displays a remarkable environmental footprint of natural acid generation, high metal and exceedingly high rare earth element (REE) concentrations in surface waters. The volcanogenic massive sulphide deposit exhibits well-constrained examples of acid-generating, metal-leaching, metal-precipitation and self-mitigation (via co-precipitation, dilution and neutralization) processes that occur in an undisturbed natural setting, a rare occurrence in North America. Oxidative dissolution of pyrite and associated secondary reactions under near-surface oxidizing conditions are the primary causes for the acid generation and metal leaching. The deposit is hosted in Devonian to Mississippian felsic metavolcanic rocks of the Mystic Creek Member of the Totatlanika Schist. Water samples with the lowest pH (many below 3.5), highest specific conductance (commonly >2500 μS/cm) and highest major- and trace-element concentrations are from springs and streams within the quartz–sericite–pyrite alteration zone. Aluminum, Cd, Co, Cu, Fe, Mn, Ni, Pb, Y, Zn and, particularly, the REEs are found in high concentrations, ranging across four orders of magnitude. Waters collected upstream from the alteration zone have near-neutral pH, lower specific conductance (370 to 830 μS/cm), lower metal concentrations and measurable alkalinities. Water samples collected downstream of the alteration zone have pH and metal concentrations intermediate between these two extremes. Stream sediments are anomalous in Zn, Pb, S, Fe, Cu, As, Co, Sb and Cd relative to local and regional background abundances. Red Mountain Creek and its tributaries do not, and probably never have, supported significant aquatic life.

Alaska↗
USGS2022

USGS Critical Minerals Review: 2021

In 2021, the U.S. Geological Survey (USGS) continued to play a central role in understanding and anticipating potential supply chain disruptions by defining and quantitatively evaluating mineral criticality. In addition, the USGS continued to evaluate new sources of domestic critical minerals by conducting mineral resource assessments, mapping and surveying regions prospective for critical minerals, re-assessing mine waste, and pursuing fundamental research in support of responsible, sustainable mining.

Mining Engineering↗
USGS2021

USGS 2020 critical minerals review

Concerns about the lack of domestic production and availability of essential mineral raw materials were a recurring theme throughout the 20th century, particularly in the periods around armed conflicts (Congressional Research Service, 2019). These concerns resulted in the designation of particular minerals as “strategic” or “critical,” terms that commonly depend on the perspective of the user, but which are generally understood to relate to mineral commodities with uses in essential applications, and which are exposed to risk of supply disruptions, with attendant implications for economic and national security interests.

Mining Engineering↗
USGS2020

Focus areas for data acquisition for potential domestic resources of 11 critical minerals in the conterminous United States, Hawaii, and Puerto Rico—Aluminum, cobalt, graphite, lithium, niobium, platinum-group elements, rare earth elements, tantalum, tin, titanium, and tungsten

In response to a need for information on potential domestic sources of critical minerals, the Earth Mapping Resources Initiative (Earth MRI) was established to identify and prioritize areas for acquisition of new geologic mapping, geophysical data, and elevation data to improve our knowledge of the geologic framework of the United States. Phase 1 of Earth MRI concentrated on those geologic terranes favorable for hosting the rare earth elements (REEs). Phase 2 continued to address the REEs and also identified focus areas for potential domestic sources of 10 more of the 35 critical minerals on the U.S. critical minerals list (aluminum, cobalt, graphite, lithium, niobium, platinum-group elements, tantalum, tin, titanium, tungsten). This report describes the methodology, data sources, and summary results for mineral systems that host these 11 critical minerals in the conterminous United States, Hawaii, and Puerto Rico; Alaska is covered in a separate report. The mineral systems framework adopted for this study links critical mineral commodities to families of genetically related mineral deposit types. The mineral systems approach is an efficient approach, providing a simultaneous evaluation of geologic terranes through aggregation of genetically related mineral deposit types that are much larger than individual ore deposits. Geologic, geochemical, topographic, and geophysical mapping provided by Earth MRI will document geologic features that reflect the extent of individual mineral systems and provide information about critical mineral deposits that may not have been recognized previously. Each critical mineral commodity is discussed in terms of importance to the Nation’s economy, modes of occurrence, mineral systems, and deposit types along with maps and tables listing examples of focus areas for each critical mineral. Important mineral systems for these critical minerals include chemical weathering systems for aluminum (bauxite); placer systems for titanium and REEs; metamorphic systems for graphite; mafic magmatic systems for platinum-group elements and cobalt; lacustrine evaporite and porphyry tin systems for lithium; and copper-molybdenum-gold (Cu-Mo-Au) systems for tungsten. REEs occur in many different mineral systems. Focus areas were developed by scientists from the U.S. Geological Survey in collaboration with scientists from State geological surveys and other institutions. This first national-scale compilation of focus areas represents an initial step in addressing the Nation’s critical mineral needs by screening areas for acquisition of new data to provide the geologic framework necessary for identifying domestic sources of critical minerals.

Open-File Report↗
USGS2020

Porphyry copper potential of the U.S. Southern Basin and Range using ASTER data integrated with geochemical and geologic datasets to assess potential near-surface deposits in well-explored permissive tracts

ArcGIS was used to spatially assess and rank potential porphyry copper deposits using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data together with geochemical and geologic datasets in order to estimate undiscovered deposits in the southern Basin and Range Province in the southwestern United States. The assessment was done using a traditional expert opinion three-part method and a prospectivity model developed using weights of evidence and logistic regression techniques to determine if ASTER data integrated with other geologic datasets can be used to find additional areas of prospectivity in well-explored permissive tracts. ASTER hydrothermal alteration data were expressed as 457 alteration polygons defined from a low-pass filtered alteration density map of combined argillic, phyllic, and propylitic rock units. Sediment stream samples were plotted as map grid data and used as spatial information in ASTER polygons. Gravity and magnetic data were also used to define basins greater than 1 km in depth. Each ASTER alteration polygon was ranked for porphyry copper potential using alteration types, spatial amounts of alteration, stream sediment geochemistry, lithology, polygon shape, proximity to other alteration polygons, and deposit and prospects data. Permissive tracts defined for the assessment in the southern Basin and Range Province include the Laramide Northwest, Laramide Southeast, Jurassic, and Tertiary tracts. Expert opinion estimates using the three-part assessment method resulted in a mean estimate of 17 undiscovered porphyry copper deposits, whereas the prospectivity modeling predicted a mean estimate of nine undiscovered deposits. In the well-explored Laramide Southeast tract, which contains the most deposits and has been explored for over 100 years, an average of 4.3 undiscovered deposits was estimated using ASTER alteration polygon data versus 2.8 undiscovered deposits without ASTER data. The Tertiary tract, which contains the largest number of ASTER alteration polygons not associated with known Tertiary deposits, was predicted to contain the most undiscovered resources in the southern Basin and Range Province.

Economic Geology↗
USGS2019

Assessment of undiscovered copper resources of the world, 2015

The U.S. Geological Survey completed the first-ever global assessment of undiscovered copper resources for the two most significant sources of global copper supply: porphyry copper deposits and sediment-hosted stratabound copper deposits. The geology-based study identified 236 areas for undiscovered copper in 11 regions of the world. Estimated amounts of undiscovered copper resources are reported at different levels of probability. The results of the assessment indicate that a mean of at least 3,500 million metric tons (Mt) of undiscovered copper associated with these deposit types may exist worldwide, exceeding the 2,100 Mt of identified copper resources tabulated for these deposit types. Porphyry copper deposits contain 1,800 Mt of identified copper resources and are estimated to contain a mean of at least 3,100 Mt of undiscovered copper resources. South America is the dominant source for both identified and undiscovered porphyry copper resources. However, several regions of Asia, including China, have significant potential for undiscovered porphyry copper resources. The amount of mean undiscovered porphyry copper resources that may be economic to extract varies as a function of likely depth to a deposit and quality of local infrastructure that could support mining. Sediment-hosted stratabound copper deposits contain 310 Mt of identified copper resources and are estimated to contain a mean of at least 420 Mt of undiscovered copper resources. The sedimentary basins that may contain significant undiscovered copper resources are the Katanga Basin in central Africa, the Southern Permian Basin of Poland and Germany, the Chu-Sarysu Basin of Kazakhstan, and the Kodar-Udokan area of Russia. Sedimentary basins in the Northwest Botswana Rift in Botswana and Namibia, the Benguela and Cuanza Basins of Angola, and the Cambrian rocks of Egypt, Israel, and Jordan are recognized as having significant potential for undiscovered copper resources in sediment-hosted stratabound copper deposits; however, these areas require additional research, analysis, and evaluation before quantitative resource estimates can be made. The estimate of at least 3,500 Mt of undiscovered copper in two deposit types provides a basis for long-range planning for this important commodity. U.S. copper consumption is 2 Mt per year, world consumption is about 20 Mt per year, and global production from these two deposit types is about 12 Mt per year. Total global copper production from all deposit types from 1879 to 2012 was about 600 Mt. The world’s use of mineral resources, such as copper, will continue to increase in the foreseeable future to support a growing world population and increasing standards of living. The world has sufficient copper to last for decades. However, increases in exploration and growth in mining capacity will be necessary to identify and develop undiscovered resources to supply projected demand.

Scientific Investigations Report↗
USGS2019

Focus areas for data acquisition for potential domestic sources of critical minerals—Rare earth elements

Rare earth elements (REEs) are critical mineral commodities for the United States. In response to a need for information on potential domestic sources of REEs in mineral deposits, the U.S. Geological Survey (USGS) identified broad focus areas throughout the conterminous United States and Alaska as a guide for selecting new geoscience research areas. This study was done to support the USGS Earth Mapping Resources Initiative (Earth MRI). Focus areas are identified in four regions of the United States (Alaska, West, Central, and East) by mineral deposit type. The areas are described in a companion USGS data release that consists of a map in a geographic information system and accompanying tables that document the rationale for each focus area (C.L. Dicken and others, 2019, https://doi.org/10.5066/P95CHIL0 ). This open-file report describes the methodology that was used to identify focus areas and determine new data acquisition needs. Deposit types that are likely to be of interest for future exploration and development of domestic nonfuel REE resources include deposits associated with carbonatites and peralkaline rocks, iron oxide-apatite deposits, monazite-bearing placers, and REE-enriched phosphorites.

Open-File Report↗
USGS2019

Tectono-magmatic evolution of porphyry belts in the central Tethys region of Turkey, the Caucasus, Iran, western Pakistan, and southern Afghanistan

Exploration in the central Tethys region of Turkey, Armenia, Azerbaijan, Georgia, Iran, and weste rn Pakistan has led to the identification of the giant Reko Diq (24 Mt Cu and 1300 t Au), Sar Cheshmeh (8.9 Mt Cu and 0.46 Mt Mo), Sungun (5.1 Mt Cu and 0.20 Mt Mo), and Kadjaran (4.6 Mt Cu, 0.94 Mt Mo, and 1100 t Au), and 10 other large (1–2 Mt Cu) porphyry deposits including Saindak, Cevizlidere, Teghout, Meiduk, and Halilağa. Continued exploration efforts have also resulted in the development of porphyry-related gold deposits such as Kişladağ (9.6 Moz Au), Çöpler (3.7 Moz Au), Aği Daği (1.7 Moz Au), and Sary Gunay (3.0 Moz Au), and in the generation of several other promising exploration projects. The distribution in space and time of porphyry deposits in the central Tethys region was shaped by complex pre- to post-mineral tectonic, igneous, collisional, uplift and burial events. These events are represented by a partially-overlapping and variably exhumed and covered collage of twenty-six Early Jurassic to Holocene magmatic belts permissive for the occurrence of porphyry deposits (porphyry tracts and sub-tracts). Twelve tracts or sub-tracts are characterized by compressional continental arcs that formed on drifting terranes or continental margins, 10 developed in compressional to extensional intra-oceanic arc and backarc-rift settings, and 4 formed in extensional post-collisional environments over amalgamated terranes. Eight of these belts were variably affected by coeval and younger metamorphic, fold-and-thrust, and extensional faulting events. Fifty-four porphyry Au-(Cu), Cu-Au, Cu-Mo, Mo-Cu deposits, 15 porphyry-related Au, Au-(Mo) and W-(Mo-Au) deposits, 239 porphyry prospects, and 68 other porphyry-related mineral sites were identified in the study region. Of the 376 porphyry and porphyry-related sites, about 11% formed in island arc, 42% in continental arc, 20% in backarc, and 27% in post-collisional settings. Of the 69 porphyry and porphyry-related deposits, 7% developed in intra-oceanic arc, 41% in continental arc, 27% in backarc, and 25% in post-collisional settings. The largest occur in either compressional continental arc (18 deposits including the Reko Diq and Sar Cheshmeh giants) or post-collisional (13 deposits including the Kadjaran and Sungun giants) environments. Ninety percent of the largest porphyry or porphyry-related deposits occur in only 9 of the 26 permissive porphyry tracts or sub-tracts. Moreover, 88, 90, and 77% of the identified Cu, Mo, and Au resources are contained in porphyry deposits that occur in only 4 of these 9 tracts. Of these 4 tracts, 3 outline arc settings, and one delimits a post-collisional environment. The compositional diversity of porphyry intrusions in these tectono-magmatic environments generally varies from island arc settings with the most restricted range (partly alkaline but mainly calc-alkaline dioritic to granodioritic-tonalitic), to continental arc (calc-alkaline dioritic-quartz dioritic, granodioritic, quartz monzonitic-granitic, and less commonly mildly alkaline), to backarc (mildly alkaline and calc-alkaline dioritic to granitic), to post-collisional settings with the most expansive range (alkaline and calc-alkaline mafic to felsic, and weakly peraluminous). Metal associations also vary broadly as a function of porphyry intrusion composition from weakly peraluminous to metaluminous felsic (Mo[±W ± Cu]; <2% of porphyry-related systems [i.e., Tyrnyauz]), to metaluminous felsic and intermediate (Cu-Mo[±Au]; 85% [i.e., Cevizlidere, Haft Cheshmeh, Kahang, Sar Cheshmeh, Sungun, Teghout, Reko Diq, Saindak]), to mildly alkaline felsic and intermediate (Cu-Au[±Mo] [i.e., Agarak, Kadjaran, Kale Kafi]) and mafic (Au-Cu; 12% [i.e., Çöpler]), and to alkaline felsic (Au-Mo; 1% of porphyry-related systems [i.e., Kişladağ). Tectonic changes were critical in triggering the formation of large porphyry deposits in the region. Large porphyry deposits were preferentially emplaced in continental arc settings shortly before major collisional events (Dar Alu, Kahang, Meiduk, Now Chun, and the giant Sar Cheshmeh and Reko Diq deposits), or in post-subduction environments shortly after collision (Bakirçay, Güzelyayla, Haft Cheshmeh, Masjed Daghi, and the giant Kadjaran and Sungun deposits) or during periods of prominent extension (Aği Daği, Halilağa, Kişladağ, Sari Gunay, and Zarshuran porphyry-related deposits). Collision-induced uplift, erosion, and removal of coeval volcanic rocks favorably exposed the hypabyssal level of subduction-related porphyry deposits. Extensional structures that developed parallel and orthogonal to the compressional principal stress component along transtensional or transpressional strike-slip faults or in pull-apart basins commonly controlled porphyry-related deposits in post-collisional settings. The latter deposits typically exhibit shallow epithermal levels of emplacement because of preservation by burial. Seventeen porphyry deposits and one porphyry-related deposit in the study region are reported to contain significant supergene resources. Relatively mature levels of secondary copper enrichment in dominantly granodioritic to granitic porphyry deposits occur in areas where large pyrite-rich quartz-sericite alteration zones have been preserved and exposed to surface oxidation (Güzelyayla and Ulutaş in northeastern Turkey; Agarak, Ankavan, Dastakert, Kadjaran, and Teghout in Armenia; Ali Javad in northern Iran; Kale Kafi in central Iran; Darreh Zar, Meiduk, Now Chun, and Sar Cheshmeh in southeastern Iran; and Tanjeel in southwestern Pakistan). Chalcocite blankets also developed over porphyry deposits in regions where significant post-mineral faulting has occurred (Muratdere and Sarıçayıryayla in western Turkey). Normal faulting also enhanced secondary enrichment of gold in the Halilağa porphyry and Sary Gunay porphyry-related deposits located respectively in western Turkey and northern Iran. Evaluation of provincial as well as local controls strongly suggests that continued exploration in the region will lead to the identification of additional porphyry and porphyry-related deposits. These deposits will likely be found under younger cover formations in porphyry belts that are already known, and in association with superjacent high- and intermediate-sulfidation epithermal deposits, or increasingly peripheral skarn, carbonate-replacement, and sediment-hosted deposits. Application of suitable exploration techniques to detect concealed and/or deformed deposits in porphyry belts that remain under-explored may also prove productive.

Tethys region↗
USGS2019

USGS critical minerals review

The United States’ supply of critical minerals has been a concern and a source of potential strategic vulnerabilities for U.S. economic and national security interests for decades (for example, see Strategic and Critical Minerals Stockpiling Act, 1939). More recently, with the rapid increase in the types of materials being used in advanced technologies (Fortier et al. 2018a), and geopolitical events surrounding the supply of rare earth elements (Ting and Seaman, 2013), among other developments, the critical minerals issue has again achieved a high level of visibility within the U.S. government (Executive Order 13817 (2017)).

Mining Engineering↗
USGS2018

USGS critical minerals review

The United States’ supply of critical minerals has been a concern and a source of potential strategic vulnerabilities for U.S. economic and national security interests for decades (for example, see Strategic and Critical Minerals Stockpiling Act, 1939). More recently, with the rapid increase in the types of materials being used in advanced technologies (Fortier et al. 2018a), and geopolitical events surrounding the supply of rare earth elements (Ting and Seaman, 2013), among other developments, the critical minerals issue has again achieved a high level of visibility within the U.S. government (Executive Order 13817 (2017)).

Mining Engineering↗
USGS2017

Environmental considerations related to mining of nonfuel minerals

Throughout most of human history, environmental stewardship during mining has not been a priority partly because of the lack of applicable laws and regulations and partly because of ignorance about the effects that mining can have on the environment. In the United States, the National Environmental Policy Act of 1969, in conjunction with related laws, codified a more modern approach to mining, including the responsibility for environmental stewardship, and provided a framework for incorporating environmental protection into mine planning. Today, similar frameworks are in place in the other developed countries of the world, and international mining companies generally follow similar procedures wherever they work in the world. The regulatory guidance has fostered an international effort among all stakeholders to identify best practices for environmental stewardship. The modern approach to mining using best practices involves the following: (a) establishment of a pre-mining baseline from which to monitor environmental effects during mining and help establish geologically reasonable closure goals; (b) identification of environmental risks related to mining through standardized approaches; and (c) formulation of an environmental closure plan before the start of mining. A key aspect of identifying the environmental risks and mitigating those risks is understanding how the risks vary from one deposit type to another—a concept that forms the basis for geoenvironmental mineral-deposit models. Accompanying the quest for best practices is the goal of making mining sustainable into the future. Sustainable mine development is generally considered to be development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. The concept extends beyond the availability of nonrenewable mineral commodities and includes the environmental and social effects of mine development. Global population growth, meanwhile, has decreased the percentage of inhabitable land available to support society’s material needs. Presently, the land area available to supply the mineral resources, energy resources, water, food, shelter, and waste disposal needs of all Earth’s inhabitants is estimated to be 135 square meters per person. Continued global population growth will only increase the challenges of sustainable mining. Current trends in mining are also expected to lead to new environmental challenges in the future, among which are mine-waste management issues related to mining larger deposits for lower ore grade; water-management issues related to both the mining of larger deposits and the changes in precipitation brought about by climate change; and greenhouse gas issues related to reducing the carbon footprint of larger, more energy-intensive mining operations.

Professional Paper↗
USGS2017

Graphite

Graphite is a form of pure carbon that normally occurs as black crystal flakes and masses. It has important properties, such as chemical inertness, thermal stability, high electrical conductivity, and lubricity (slipperiness) that make it suitable for many industrial applications, including electronics, lubricants, metallurgy, and steelmaking. For some of these uses, no suitable substitutes are available. Steelmaking and refractory applications in metallurgy use the largest amount of produced graphite; however, emerging technology uses in large-scale fuel cell, battery, and lightweight high-strength composite applications could substantially increase world demand for graphite. Graphite ores are classified as “amorphous” (microcrystalline), and “crystalline” (“flake” or “lump or chip”) based on the ore’s crystallinity, grain-size, and morphology. All graphite deposits mined today formed from metamorphism of carbonaceous sedimentary rocks, and the ore type is determined by the geologic setting. Thermally metamorphosed coal is the usual source of amorphous graphite. Disseminated crystalline flake graphite is mined from carbonaceous metamorphic rocks, and lump or chip graphite is mined from veins in high-grade metamorphic regions. Because graphite is chemically inert and nontoxic, the main environmental concerns associated with graphite mining are inhalation of fine-grained dusts, including silicate and sulfide mineral particles, and hydrocarbon vapors produced during the mining and processing of ore. Synthetic graphite is manufactured from hydrocarbon sources using high-temperature heat treatment, and it is more expensive to produce than natural graphite. Production of natural graphite is dominated by China, India, and Brazil, which export graphite worldwide. China provides approximately 67 percent of worldwide output of natural graphite, and, as the dominant exporter, has the ability to set world prices. China has significant graphite reserves, and China’s graphite production is expected to increase, although rising labor costs and some mine production problems are developing. China is expected to continue to be the dominant exporter for the near future. Mexico and Canada export graphite mainly to the United States, which has not had domestic production of natural graphite since the 1950s. Most graphite deposits in the United States are too small, low-grade, or remote to be of commercial value in the near future, and the likelihood of discovering larger, higher-grade, or favorably located domestic deposits is unlikely. The United States is a major producer of synthetic graphite.

Professional Paper↗