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By G. A. Doyle

Until the suspension of conventional operations in 1996, the White Pine Mine was the second-largest active underground copper mine in the United States, underlying an area of approximately 30 km2 (13 sq. miles) in the Upper Peninsula of Michigan. The mine operator intends to initiate in-stope solution copper mining by circulating a solution (lixiviant) of mine water, sulfuric acid and ferric iron through rubblized ore. As planned, the solution would be retired in the mined-out stopes following completion of the solution-mining activities. Investigations into the fate of the retired solution indicated that the solution, through time, would change from an acidic, metal-rich solution to a near-neutral, reducing solution containing much lower concentrations of metals. Investigations included reaction-path modeling (EQ3/6) and laboratory and in-mine tests. The combination of neutralization and reduction will result in precipitation of most metals, primarily as metallic sulfates, chlorides and sulfides.

Jan 1, 1997

By A. Gene Collins

The demand for lithium may increase because of its potential use id lithium batteries and in the generation of electrical power by fusion. Therefore, lithium abundance in some United States oil-field brines was surveyed. Oil-field brines from numerous locations were found to contain more than 100 mg/l lithium and several exceeded 500 mg/l. An area of 25,000 km2, with a reservoir thickness of 60 m, an effective porosity of 5 percent, and a brine with a specific gravity of 1.2 containing 100 mg/l of lithium, contains about 0.75 x 106 tonnes (1 tonne = 1 metric ton = 1,000 kg) of lithium in 7.5 km3 of brine. It is postulated that the brines were enriched in lithium by lithium-rich spring water or lithium leached from volcanic rocks followed by evaporation sequences.

Jan 1, 1978

By Alden B. Carpenter

The Dead Sea is the only relatively large body of surface water having bromide concentrations comparable to those in the brines of the Smackover Formation in Arkansas. The Dead Sea, like the Smackover brines, contains a great deal of calcium and is very low in sulfate and iodide. The relationships between potassium, divalent cations, and chloride indicate that over 20 percent of the bromide in the Dead Sea is derived from some source other than by the evaporation of sea water. A similar type of study of the Smackover brines in Arkansas indicates that approximately 60 percent of the bromide has been derived from some source other than sea water. Both the Dead Sea and Smackover brines are very low in iodide suggesting that the excess bromide has not been derived from organic matter. The origin of the excess bromide is probably the same for both of these brines, but the source of this bromide remains unknown.

Jan 1, 1978

By Zohreh Kazemi Motlagh, Virginia T. McLemore

Critical minerals are nonfuel minerals, essential to the U.S. economy and national security, whose supply chain may be disrupted. Mine wastes are potential sources of critical minerals. The goal of this project is to estimate and characterize critical minerals endowment in three mining districts in New Mexico: Black Hawk (Grant County), Hillsboro (Sierra County), and Magdalena (Socorro County), and assess their acid-generating potential. The Black Hawk district is an arsenide five-element vein deposit (Ag, Ni, Co, As, U, Bi, and local minerals like Pb, Cu, Zn, W, and Sn). The Copper Flat mine in Hillsboro district is a copper porphyry deposit. The Kelly mine in Magdalena was first mined at 1878 and are carbonate-hosted Pb-Zn deposits. Mine waste rock piles and tailings are sampled using USGS Beta sampling procedure. Geochemistry results show that Black Hawk district mine wastes samples are elevated in Ag (>200 ppm), Co (290 ppm), Ni (2,130 ppm), and Zn (8,463 ppm). Copper Flat mine tailing is elevated in Bi (111 ppm), Cu (7,453 ppm), and Zn (2,360 ppm). Downhole profile plots in Copper Flat show the positive correlation between Cu, S and Te values. Magdalena samples are elevated in Cu (5,700 ppm), Zn (129,500 ppm), and Pb (58,100 ppm). Determination of acid-generating potential in these areas suggests that Black Hawk district mine wastes are non-acid-forming while high S present in some Copper Flat and Magdalena samples can potentially cause acid mine drainage.

Feb 1, 2025

By Virginia T. McLemore, Abena S. Acheampong-Mensah

Critical mineral endowment of mine wastes in two mining districts in New Mexico (Copper Flat at Hillsboro and Carlisle-Center mines in the Steeple Rock district) will be characterized and estimated. “Beta-testing” of USGS procedures was performed. Potential critical minerals at these deposits include As, Bi, Te, Zn, Co, Ni, Mg, Mn, and fluorite. pH and particle size of samples were analyzed to determine weathering and migration potential of heavy metals. Soil pH was also measured to determine the potential for Acid Rock Drainage. The pH of the waste rock piles ranged from 3.66 to 5.67 which indicates fine- grained pyrite or sulfide oxidation. The samples collected from the tailings however, showed a different range of pH, from 6.30 to 8.62, probably due to the presence of carbonates. Difference in particle size fractions and its distribution along the slope are generally influenced by natural occurrences (e.g., gravity and pre-mining hydrothermal alteration) and operational activities such as material piling or dumping. Future work includes analyses of mineralogy and particle size correlation and estimation of critical mineral endowment of these mine wastes at New Mexico.

Feb 1, 2024

By Evan J. Owen, Virginia T. McLemore

There are tens of thousands of inactive mine features in 274 mining districts in New Mexico (including coal, uranium, metals, and industrial minerals districts). However, many of these mines have not been inventoried or prioritized for reclamation. Many of these mines have existing mine wastes, generated during mineral production, which could have potential for critical minerals, especially since the actual mineral production was generally for precious and base metals and not critical minerals. The purpose of this project is to characterize and estimate the critical mineral endowment of mine wastes and “beta-test” USGS sampling procedures. This project is important to the state of New Mexico because critical mineral resources must be identified before land exchanges, withdrawals or other land use decisions are made by government officials. Future mining of mine wastes that potentially contain critical minerals will directly benefit the economy of New Mexico. Possible re-mining of mine wastes could clean up these sites and pay for reclamation. Furthermore, this project will include training of younger, professional geologists and students in economic and reclamation geology by the PIs.

Feb 1, 2024

By Walter E. Dean

Deep-sea manganese nodules are considered to be potential ores of manganese, nickel, cobalt, and copper. Considerable time, effort, and funds have been applied to the study of Se distribution of nodules on the sea floor and the location of economically important areas, but little effort has been spent in understanding the origin of nodules. Most theories that have been proposed to explain the origin of manganese nodules have been based on inorganic physicochemical processes. It is not by coincidence, however, that the area considered to be most economically feasible is in the zone of high biological productivity in the eastern equatorial Pacific Ocean and underlain by siliceous biogenic sediment. The genesis of manganese nodules and the concentration of many trace elements are intimately associated with biological processes.

Jan 1, 1982

By Samuel B. Romberger

During the formation of most epithermal precious metal deposits geochemical changes can be characterized by the introduction of large amounts of silica, minor amounts of sulfur, and trace quantities of gold, silver, and other metals. During the same process, large amounts of alkalis and alkaline earth elements, such as sodium and calcium, and sometimes aluminum are removed from the rocks. In deposits hosted by carbonate sedimentary rocks large amounts of carbonate may be removed before or during the silicification process. Small amounts of iron may be introduced by the mineralizing solutions, however, in most epithermal deposits this may be a relatively immobile component and is locally derived. The results of these changes are deposits consisting of up to 90 to 95 percent silica as quartz veins, breccias, silicified host rocks, and jasperoids containing a few percent sulfides, mostly pyrite, and a few parts per million gold and silver. Other minerals commonly but not always present are barite, arsenic, antimony, or mercury sulfides, and tellurides. Often gold shows a spatial, and therefore an apparent genetic, relationship to pyrite in primary ores. Alteration and gangue assemblages sometimes include sericite and/or adularia, and parts of the deposits may contain alunite and/or clay minerals. Even though the value of these deposits usually lies in their gold content, silver is usually present in larger quantities than gold (Romberger, 1990). Based on these general characteristics observed in a large number of epithermal deposits, together with processes occurring in active geothermal areas to which they are often genetically linked (Henley, 1985), a model is proposed whereby deposition occurs along a subhorizontal zone separating environments of contrasting chemistries. The upper environment is characterized by oxygenated acid waters and the deeper environment by a reducing near neutral aqueous system. The model describes the chemical changes occurring as a result of mixing and/or boiling within this zone. It builds upon the physical models proposed by Romberger (1988a) for disseminated gold deposits and Bonham (1988; 1989) for volcanic rockhosted deposits.

Jan 1, 1990

By Antonio Pineda, Roger K. McLimans, Felicity E. Lloyd

lmenite is a primary ore feed to the DuPont chloride process for the manufacture of titanium diox-ide pigment. We seek to determine ilmenite geochemistry as a function of original source and as-certain which ilmenites have chemistry most amenable to upgrading via iron-leaching (leucoxenization) and that have favorable, with respect to pigment manufacture, trace element content. Ilmenite geochemistry is a function of its primary origin and of subsequent alteration. Heavy mineral sand deposits may contain ilmenite from one or several dominant source rock(s). In addition, ilmenite may alter in the weathering environment, changing the major element compo-sition (iron-leaching) and certain of the minor element content. A primary objective is to classify ilmenites in relation to origin in order to fingerprint source rocks in provenance determination. The changes in trace element chemistry during alteration are also investigated. A “decision tree” is developed to classify ilmenite types and source rock origins. Ultimately, with those methods and by amassing a database of ilmenite types from worldwide locations, it should prove possible to determine ilmenites (and their sources) more susceptible to iron leaching in the weathering en-vironment. Such ilmenites, enhanced in their titanium content, are the preferred ore targets. The method used is electron microprobe analyses at elevated conditions of voltage, cur-rent, and counting time to enable higher precision. In-situ ilmenites from igneous, metamorphic, and altered rocks (saprolites) are analyzed. Initial foci for sedimentary ilmenites are restricted provenance (approaching monogenetic, examples from Spain, Portugal) and polygenetic prove-nance (Denmark). Altered ilmenites, including the DuPont Florida ore, are used to characterize the chemistry of leucoxenization. Trace element concentration, detectability, and cost considera-tion, led to focus on Mn, Mg, V, Cr, and Nb to develop a classification scheme validated by dis-criminant analysis and “classification-regression trees”. Results show a high degree of success for restricted provenance study and an acceptable one for polygenetic provenance.

Jan 1, 2005

By Felicity Lloyd, Stuart Kearns, Roger McLimans

The metamorphic terrane of southwestern India is a geological environment containing ilmenite source-rocks, transport drainage systems, and resultant beach sand deposits that contain altered ilmenites greater than 60wt% TiO2. As such, this environment provides a geological laboratory, from source to deposit, for the investigation of ilmenite origin, alteration, and geochemical character. Ilmenite samples from potential source rocks, river sands, and beach sands all show degrees of alteration and a variety of alteration textures (iron leaching) producing leucoxene (here defined as >70 <90wt% TiO2) and progressing to rutile (here defined as >90wt% TiO2). Distinct alteration textures are specific to different source rocks and are used together with trace element geochemistry as provenance criteria. Ilmenites are classified on the basis of their trace element content. In India, the ilmenites are classified principally according to the Mg, Nb, and Mn content and this signature defines potential source rocks, even where the ilmenite is altered to a TiO2 content of 70wt%. The trace element data may fingerprint source rocks whose ilmenite is more prone to iron leaching and that criterion has application in exploration for higher-grade ilmenites.

Jan 1, 2005

By Paula N. Wilson, W. T. Parry

Carbonaceous and metalliferous black shales occur in close proximity to Mercur-type gold deposits in the southern Oquirrh Mountains, Utah. These shale units, the Manning Canyon shale and the Long Trail shale, have undergone regional hydrothermal alteration. Hydrothermal solutions oxidized organic matter and pyrite, replaced shale by hydrothermal phyllosilicates and silica, and replaced fossils by phyllosilicates. The shales are depleted in organic carbon, calcium carbonate, alkali and alkaline earth metals, and enriched in aluminum and hydrogen. Hydrothermal veins containing illite, chlorite, pyrophyllite, kaolinite, Fe-oxides, and sulfides are present throughout the study area.The illite in veins is an ammonium illite that contains up to 2 % NH4 and is correspondingly depleted in K. Correlations among Au, As, Hg, TI, Sc, and rare earth elements indicate that hydrothermal fluids responsible for formation of ammonium illite were gold bearing. K/Ar ages of illite veins and illite-rich, clay-size separates of altered shales indicate hydrothermal activity occurred in the time range 193 to 122 Ma. Several ages from clay-size separates within the Mercur district cluster near 160 Ma. These ages are coeval with thrust faulting recognized to the north and west.

Jan 1, 1990

By Andy B. Wallace

Veins in the Pyramid district of northwestern Nevada occur along steep fractures in Oligocene and Miocene quartz latite tuffs. The vein mineralization is zoned from a central enargite-pyrite zone outward through a complex polymetallic intermediate zone and an outer zone of galena and pyrite. Wall rock alteration includes advanced argillic and sericitic envelopes along veins superimposed on district-wide propylitization. The ore distribution and alteration patterns were probably produced by an increase in pH, a decrease in sulfur fugacity, along with cooling of the migrating hydrothermal fluid.

Jan 1, 1978

By Gary A. Nowlan

The Casa Grande West-Santa Cruz porphyry-¬copper deposit is in the Basin and Range physiographic province west of Casa Grande, Arizona (Fig. 1). The Casa Grande West portion of the deposit is controlled by Casa Grande Copper Company and the Santa Cruz portion by ASARCO. The deposit contains at least 350,000,000 metric tons of rock with greater than 1 percent Cu. The deposit is covered by at least 300 m of sediment, with no visible expression of the deposit at the land surface. The deposit is in an area of prime agricultural land that depends heavily upon well irrigation because of a hot and arid climate. Because of the deep sedimentary cover, the chance is extremely remote that the geochemistry of soil or stream sediment would reflect the deposit even if the land surface were not disturbed by many years of farming. Irrigation wells of the area generally bottom in the sedimentary cover. The purpose of the study is to see if the Casa Grande West-Santa Cruz deposit is geochemically reflected in ground waters over and near the deposit.

Jan 1, 1981

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Southwestern New Mexico is part of a large belt of Late Cretaceous to Eocene copper porphyry deposits found in Arizona, New Mexico, and Mexico. These deposits are the result of arc magmatism that occurred during the Laramide orogeny. Recently, attention has been brought to other commodities that can be extracted as by- and co-products, many of which are critical minerals. A new compilation of the geochronology of these deposits shows two main pulses of magmatism that produced mineralized deposits and, along with new dates by the author, shines new light on the geologic history of these deposits and the role it plays in critical mineral abundance.

Feb 1, 2024

By Richard M. Crowell, John W. Shield, Todd J. Harvey

Facing lower gold prices, gold mine operators throughout the world are seeking ways to reduce costs for treating refractory sulfide ores. Many gold mines, currently producing oxide ores, have underlying refractory sulfide deposits and the operators could extend the mine life by processing these sulfides. Fortunately, oxidation technologies for refractory ores need not be complex nor costly. GeoBiotics, Inc. has developed heap biooxidation technologies (GEOCOAT™) for treatment of refractory gold ores and concentrates. GEOCOATTM uses simple low cost unit operations common to heap leaching of gold and copper ores. The cost effectiveness and flexibility of GEOCOAT™ heap biooxidation allows mining companies to expand operations to include refract01y ore. In addition, GEOCOAT™ can be utilized to supplement or replace existing oxidation processes such as roasting, autoclaving, or agitated tank biooxidation, and to treat a lower resource grade than is currently economic. The GEOCOAT™ technology involves coating sulfide concentrates onto sized support rocks and biooxidizing the sulfides in a heap configuration. After biooxidation the concentrate is stripped from the support rock, neutralized and leached in conventional cyanidation facilities. Ashanti Goldfields Company Ltd. (AGC) produces over 885,000 ounces of gold per year from oxide and refractory ores at its Obuasi operations in Ghana. Refractory flotation concentrates are treated in roasters and in the world's largest stirred tank biooxidation facility. In August 1998, AGC and GeoBiotics jointly constructed and operated a field demonstration heap of the GEOCOATTM process at the Obuasi operations. The heap contained I 082 tonnes of support rock and 125 tonnes of concentrate. The heap was approximately 19 meters square at the base and 3.8 meters high, and ran for 88 days after which the concentrate was reclaimed. Average gold recovery after biooxidation was 91.5% with a NaCN consumption of 8.6 kg/t. Baseline gold recovery by direct cyanidation of the concentrate was 53.8%.

Jan 1, 1999

By Vitaly T. Borisovich

Mining economics courses have been taught in Europe for more than two centuries and in the United States for most of this century. They are the mineral industry&apos;s version of engineering economics offered by industrial engineering departments. In the 1930s, mineral economics first appeared in American mining schools. This subject goes beyond the deposit and the mine. It examines the economic aspects of mineral resources in general and the individual mineral industries in particular. In 1947, the first degrees in mineral economics were granted in the United States. There are mining and geological engineers who specialize in mining economics. But it has rarely become a separate degree program. Rather, in this country and several others, a graduate student in a mining department or school will include economics in his course work. Then the person writes a thesis or dissertation on a mining economics topic. One exception is found in Moscow at the Department of Geoeconomics of the Moscow Geological and Prospecting Institute (MGPI). To place this program in perspective, some background is needed on education in the Soviet Union.

Jan 1, 1991

By David V. Fitterman, David L. Campbell

We&apos;ve used direct current resistivity (DC), electromagnetic (EM), induced polarization (IP), and ground-penetrating radar (GPR) geoelectrical methods to study mine dumps. The results reflect lithology, pore water saturation, and dissolved solids in the pore water. If the pore water has a pH less than 5, conductivity maps can indicate acid generating potential. IP measurements can help distinguish mineralogy in mine dumps, especially concentrations of sulfide minerals. EM and DC can help locate acidic/high TDS groundwater associated with mine dumps. GPR methods failed at the sites we studied in the West. Our own conclusions are augmented by those from the recent literature.

Jan 1, 2000

By Charles N. Alpers, Jane M. Hammarstrom, Robert R. II Seal, Nora K. Foley

Geoenvironmental models are compilations of geologic, geochemical, and hydrologic information that describe both the pre- and post-mining environmental signatures of mineral deposits. The environmental behavior of seafloor massive sulfide deposits varies according to deposit type. This study has divided massive sulfide deposits into six categories: (1) Noranda-type, (2) Kuroko-type, (3) Cyprus- type, (4) Bathurst-type, (5) Besshi-type, and (6) sedimentary-exhalative deposits. In addition to Fe and Al, the heavy metals most commonly associated with drainage from these deposits are Cu, Zn, Cd, Pb, and As. Metal ratios of mine drainage and natural background waters tend to reflect the primary character of the ores. Variations in pyrite and pyrrhotite contents are reflected in lower pH values associated with pyrite-rich deposit types.

Jan 1, 2000

By Jon Kellar, Samuel Kessinger, Prasoon Diwakar

Tantalum (Ta) and niobium (Nb) are extracted from many different ore types. The major economic orebody mined for tantalum and niobium consists of tantalite ((FeMn)Ta2O5) and columbite ((FeMnNb2O5)) in a solid-solution mineral commonly referred to as “coltan.” The largest supplying region, The Democratic Republic of the Congo (DRC), is unfortunately also the most ethically compromised source for this critical mineral. Officially, the U.S. government has deemed coltan ore from the DRC a “conflict mineral” [1]. The lack of pragmatic and effective local mining regulation in Central Africa, when coupled with high levels of violence and corruption, has spawned a widespread, illegal, unethical and, most importantly, unsafe economy. This illicit economy is centered around first, illegally mining these valuable conflict minerals and second, smuggling these minerals into the global supply chain. Handheld spectroscopy devices could provide further transparency to these opaque supply chains, giving miners, traders and refiners the ability to authenticate the provenance of the minerals they encounter, and allowing companies to prove compliance with the regulatory agencies attempting to curtail illicit mining.

Mar 1, 2025

By M. J. Price

The usage of Geographic Information Systems (GIS) is increasing rapidly throughout the Mining Industry, especially in the Industrial Minerals sector. GIS provides an efficient and robust link between spatial (often CADD) and tabular (database/spreadsheet) components. Mineral economists and corporate planners employ GIS to perform market analyses, to source raw materials, and to schedule and monitor deliveries to customers. Exploration and acquisition groups apply spatial analysis to identify high quality resources that meet economic guidelines. Mining regulators and environmental affairs departments expedite and monitor permitting, environmental compliance, and best management practices reclamation through GIS data management and Electronic Permitting. Operations staffs monitor overburden removal, material extraction, quality control, and stockpile volumes with GIS. This paper summarizes the many aspects of GIS in Industrial Minerals. It also introduces and addresses issues and concerns commonly encountered during a mining GIS implementation.

Jan 1, 2001