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By Kermit Allen

Storing natural gas in solution mined salt cavities appears to be one of the more promising methods being considered by some major gas transmission companies for meeting peak demands. Historically, these companies have been faced with the problem of meeting peak demands when the source of natural gas is located hundreds of miles from the marketing area. Transcontinental Gas Pipe Line Corporation's position was further complicated because some of its offshore Gulf Coast gas supply wells may have to be shut in during hurricane alerts. Transco's solution was to construct. solution mined salt storage caverns adjacent to its pipeline near Eminence, Mississippi. (See Figure 1.) In 1965, Fenix & Scisson, Inc., was engaged by Transco to evaluate the feasibility of storing natural gas in caverns dissolved from salt at selected locations along Transco's pipeline to the East Coast. In June of that year a report was submitted to Transco concluding that this proposal was feasible and recommending several potential sites for storage development. Additional engineering and geological studies followed and in March 1968 the Eminence Salt Dome site was selected and storage construction began that year.

Jan 1, 1971

By P. G. Vikre

Several factors have caused less emphasis to be placed on geologic mapping in mineral exploration in the last 15 years. These include opportunities for "easy" discoveries of near surface gold and silver deposits in developed countries, and of base metal deposits as well in less developed countries, a decline of emphasis on geologic mapping in many universities, and a decline of useful mapping by government agencies in many areas. Geologic mapping is simply a way of recording geologic observations on volumes of rock larger than can be seen from one place. Since most geologic processes involve systems larger than this, mapping is also essential to understand the significance of observations made on smaller volumes of rock, such as thin sections and sample taken for chemical or isotopic analysis. To be useful, the observations recorded through geologic mapping are then interpreted to arrive at an understanding of the 3D geometry and geologic history of a volume of rock, which is used to direct mineral exploration, or any number of other purposes.

Jan 1, 1995

By D. C. Martin

Construction of the Cerro Colorado on-off leach pad in northern Chile required placement of approximately 3,000,000m3 of fill over a P1an area of approximately 600,000m in irregular terrain with relief of up to 40m. Earthwork construction was completed in approximately six months using mine waste which was placed in 4 to 6m lifts using mine haul trucks. The lift thickness was reduced and the compactive effort increased in the upper 10m to enable development of a mat and additional resistance to possible differential settlements under dynamic (earthquake) conditions. A single 80 mil (2mm) HOPE liner was used below the leach pads and this was protected from the loading and unloading equipment using an engineered liner system consisting of screened sand, gravel and silt from local sources as the bedding and cover layers, and a heel of screened gravel and primary crushed low grade ore. Settlement monitoring, field testing and subsequent assessments of liner performance have indicated an adequate design was achieved and the project proceeded with considerable savings in time and construction costs.

Jan 1, 1995

By Chee Theng

"What would you do if you are an industry leader and disruptive technology threatens to overturn your business model? Although bearings and seals are in little danger of being displaced in the near future, one company is taking no chances in an age of digital disruption.“For SKF, digital transformation and the Industrial Internet of Things (IIoT) make this time right now arguably the most exciting time in our 100-plus years of history,” John Schmidt, president of SKF USA Inc., said during the SKF Technical Press Day in Philadelphia, PA.The company is not merely integrating digital technologies into its products and services but is taking a forward-looking, strategic approach. “To be successful, legacy companies have to undertake a process called digital transformation. It’s not just an IT initiative but is really about upgrading the strategic thinking,” explained Michael D’Argenio, vice president of digital transformation and customer experience at SKF Americas.Learning from those who went beforeD’Argenio cited the examples of two companies that saw entirely different outcomes in the face of digital disruption. The well-known case is that of Kodak, one of the storied brands in history, whose business was disrupted by the advent of digital photography. Although it invented digital photography, Kodak decided to box it up and put it on the shelf because it was scared of disrupting its business in photographic fim. Instead, it was disastrously disrupted from the outside.Less well known is the case of Encyclopedia Brittanica Inc., publisher of the longest-running English-language, general-knowledge encyclopedia in the world. Sales peaked at 120,000 sets in 1990, plunging to 8,000 sets in 2012. In 20 short years, it saw not one but two massive digital disruptions. The first was in 1993, when Microsoft published the first digital interactive encyclopedia on a CD-ROM, called Encarta, priced at just $99. The second was in 2001, when a communitycurated, free website called Wikipedia launched. Taking the opposite approach from Kodak, Encyclopedia Brittanica looked at its industry, its company and its customers through the lens of the new technologies, made a prediction about the future and, based on that prediction, took a bold move. Having identified its core value proposition as the delivery of reliable, high-value, verifiable knowledge, Encyclopedia Brittanica replanned, restructured and rebuilt its company from the ground up to deliver that same value proposition, only in a different way. It stopped producing the only product that it had known for 244 years and began producing digital products that it sold to educational institutions.“There is a lot to learn from the Encyclopedia Brittanica case,” said D’Argenio. “The company embraced its market change, it embraced its customer change, and it rethought what it needed to do to be successful. Because it owned that disruption internally, it was never disrupted from the outside. It continues to operate today and is as profitable as it has ever been.”"

Aug 1, 2019

By A. R. Laplante

A test to determine the amount of gravity recoverable gold (GRG) in an ore is described. Typical GRG results are given; an error analysis is detailed; possible uses are discussed. Of the 38 samples tested, the lowest GRG content was found to be 25% (most below 25 11m, or 600 mesh), and the highest 94% (most above 300 11m, or 50 mesh). The average GRG content was 63%, with a standard deviation of 19%. Error analysis shows the test to be reproducible within 5 to 10%, depending on the size distribution and grade of GRG, and the sample extraction protocol. When using the same primary sample, reproducibility improves, 2 to 5%, depending on the amount of gold coarser than 850 11m (20 mesh) and sample weight. The test has been applied to greenfield project and retrofit applications, to determine the suitability of gravity recovery. For existing circuits, it has been coupled with a model of gravity recovery for optimization studies.

Jan 1, 1996

By Joseph Peterson, Alexander May

The Bureau of Mines used geochemical modelling computer programs to characterize a site containing lead slag generated by a lead processing facility. Tests for toxic elements by the U. S. Environmental Protection Agency (EPA) extraction procedure showed that all elements except lead were in compliance. Concentrations for lead ranged from 28 to 30 ppm. However, analysis of water samples from monitoring wells resulted in no lead concentrations that exceeded the National Drinking Water Standard. A discussion of a computational program to calculate concentrations of lead species and several other ions is presented.

Jan 1, 1991

By C. Zhou, R. Jacksha

This paper reports measurement results for radio frequency (RF) propagation around 90° corners in tunnels and underground mines, for vertically, horizontally and longitudinally polarized signals. Measurements of signal power attenuation from a main entry into a crosscut were performed at four frequencies — 455, 915, 2450 and 5800 MHz — that are common to underground radio communication systems. From the measurement data, signal power loss was determined as a function of signal coupling from the main entry into the crosscut. The resultant power loss data show there are many factors that contribute to power attenuation from a main entry into a crosscut, including frequency, antenna polarization and crosssectional entry dimensions.

Jan 1, 2016

By G. E. Viens

The electric arc furnace has characteristics which make it attractive for a number of metallurgical applications. Some of these characteristics are: high thermal efficiency, the possibility of attaining very high temperatures, low off-gas volume compared to fuel-fired furnaces, no impurities are introduced by the heat source, and impurities in only minor amounts are introduced by the electrodes. It also has disadvantages, the chief ones being the relatively high cost of electrical energy compared to fossil-fuel energy and the fact that, when oxide ores are smelted using carbon as reductant, the off-gases emitted are rich in carbon monoxide. As in many other pyrometallurgical processes, fumes and dust are emitted from melting or smelting operations. In many installations, some or all of the off-gases are flared, thereby wasting their energy and contributing to atmospheric pollution. During the last eight years, a shaft-electric furnace has been under development at the Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada. This project was initiated to try to overcome, or at least minimize, the disadvantages of the electric furnace. Experience on other projects, prior to the beginning of this program, had indicated that preparation of the charge materials, for example by sizing raw ore, sintering concentrates and crushing and sizing the sinter, or agglomerating concentrates into uniform-sized pellets, could make a substantial contribution towards achieving success in arc-furnace smelting projects; This entire

Jan 1, 1971

By Ray Brainard, Adriana Ventimiglia, Amanda Kerr

The $2 billion Horizon Lateral includes over 30 miles of trenched and tunneled pipeline with diameters up to 120 inches.Related infrastructure includes large and small pumping stations, reservoirs, and flow control facilities. This paper will discuss the strategy and processes used to determine contract packaging and contracting delivery methods for the various project elements with an emphasis on the tunnels and trenchless crossings. Prior Authority experience and the rigorous risk-based approach to develop the preferred alignments played a large role in determining the outcomes along with schedule concerns and permitting and easement acquisition.

Jun 13, 2023

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries to be developed in recent years Minera Peñasquito, S.A. de C.V., a wholly owned subsidiary of Goldcorp Inc. has developed the Peñasquito property to produce an average annual production of 120 kilo tonnes of lead containing 0.5 million oz gold and 30 million oz silver and 250 kilo tonnes of zinc containing 20 thousand oz gold and 1.5 million oz silver.. The Peñasquito property covers a 39,000 hectare area in the western half of the Concepción del Oro district in the northeast corner of Zacatecas State, Mexico, approximately 24°45'N latitude/101°30'W longitude. The sulfide reserves are 1,009 million tonnes containing 3.33 million tonnes of lead, 7.26 million tonnes of zinc, 16.5 million ounces of gold and 1,000 million ounces of silver. This paper describes the work to justify the installation of HPGR to process the crushed SAG mill pebbles. The SAG mill-Ball mill and Cone crusher (SABC) grinding circuit is an accepted grinding circuit to optimize power consumption relative to throughput. The installation of a HPGR to process the Cone crusher product is the next step in optimizing the power consumption relative to throughput. The concern expressed by some on not moving on this change in grinding circuit was the capital and operating cost of a HPGR. The pebbles from the SAG mill can be the more abrasive and are the harder particles of the ore. Goldcorp investigated the wear and processing costs of installing a HPGR to treat the crushed pebbles. The conclusion was the installation would be a very positive economic factor in the operation of Peñasquito. This is the first application of the use of HPGR to process crushed pebbles. Minera Peñasquito and M3 Engineering selected Polysius to provide a Polycom 2417 with twin 3,000 kW drives. A comprehensive test program at Polysius has shown for 7% higher circuit power it is possible to get approx 23% higher tonnage. This coupled with full utilization of the SAG and Ball Mill available energies and with proper control of the transfer size from the SAG to Ball mill circuit there is the potential to achieve 65,000 mtpd per line or a 30% total capacity increase. The cost of power for this increase in grinding capacity is 4.8 kWh/tonne.

Jan 1, 2010

By B. R. Waples

Sometimes a project is born easy, sometimes a project has a hard time being born. Probably every project can say we had tremendous problems to overcome and they would all be right. This project had all things happen to it. Born easy, a hard time after being born, there were tremendous problems to overcome but here it is, a major copper project, a major operation, and a new source of copper for Mexico and the world market. La caridad is an ore body located in the state of Sonora in northwestern Mexico. It is at an elevation of 1,200 meters above sea level and the nearest major city is Hermosillo, the capital city of Sonora. Hermosillo is located approximately 270 kms (about 168 miles) to the southwest of la caridad. North of la caridad, 130 kms (about 81 miles), is the U.S. border town of Douglas, Arizona, which has a sister city on the Mexican side of the border -Agua Prieta.

Jan 1, 1979

By M. J. Hrebar

A study was conducted to evaluate the applicability of large wheel loaders (Cat 994 class) as primary loading equipment in open pit iron ore operations. Field visits were made to taconite and gold mines that used large wheel loaders. Data were gathered on loader selection rationale; operating and maintenance experience; and production, availability, and cost information. Brief time studies were conducted to indicate machine performance and utilization. The paper summarizes the field data and includes economic comparisons of wheel loaders versus cable shovels in an iron ore application.

Jan 1, 1996

By James M. Barker

Industrial minerals are critical to most aspects of modern society. They are pervasive in both industry and in everyone's lives (McVey, 1989; Barsotti, 1993). They are also the dominant class of minerals produced in the United States but this fact is little known outside the industry. For example, in 1993 (U.S. Bureau of Mines, 1995, table 1) industrial mineral dollar value was double that of metals ($20.86 billion vs. $10.88 billion) and employment levels were nearly so (74,000 vs. 40,000). A further difference is that transportation tends to dominate production costs (FOB end user) whereas they are much less significant in other mining ventures or other industries. Finally, metal mines are more concentrated west of the Mississippi; industrial mineral operations are more prevalent to the east (U.S. Bureau of Mines, 1995, p. 16-17). The significance of transport cost is discussed in Part 2, which is essentially Barker and Austin, 1995. Part 1 will update and expand portions of Barker and Austin (1995) and provide a more detailed discussion of import/export relationships using a China/United States reference point because of China's dramatic influence on some industrial mineral markets since the mid-1980s (barite, etc.).

Jan 1, 1996

By G. L. Simmons.

Many large. low-grade (refractory) sulfide gold resources exist in Nevada and other parts of the world that are not amenable to concentration by conventional flotation practice, Over the past several years Santa Fe Pacific Gold (SFPG) has investigated flotation process options to economically treat low-grade refractory resources of this type at Lone Tree and Twin Creeks. Conventional flotation technology applied to the original high-grade gold resources at Lone Tree and Twin Creeks was initially unsuccessful. Review and analysis of auriferous (gold-bearing) iron sulfide mineralogical characteristics and flotation chemistry provided a fundamental understanding that led to the development of a new flotation process that SFPG refers to as N2TEC. This paper discusses the development of this technology and compares N2 TEC results with conventional flotation practice.

Jan 1, 1997

By J. A. Ober

"In 2016, the estimated value of total nonfuel mineral production in the United States was $74.6 billion, a slight increase from the revised total of $73.4 billion in 2015 (Table 1). Increased construction activity spurred increased production of industrial minerals, especially those used in infrastructure and residential construction. Although starting the year relatively low, prices for several metals, especially for some of the precious metals, began to trend upward. Decreased production of most metals produced in the United States, however, contributed to an overall decline in the value of metal production.Several U.S. metal mines and processing facilities were idled or closed permanently in 2016, including iron ore mines in Michigan and Minnesota; three primary aluminum smelters in Indiana, Missouri and Washington; one secondary zinc smelter in North Carolina; a titanium sponge facility in Utah and titanium mineral operations in Virginia. In addition, in May, the weekly average rig count for oil and gas drilling reached its lowest level since the 1940s when that measurement was first recorded. The reduced drilling activity resulted in decreased production of some industrial mineral products used in the drilling sector. Trends in mineral-related sectors of the domestic economy declined or held steady, except in the manufacturing of nonmetallic mineral products and nonferrous metals excluding aluminum, which increased. Overall, mining trended downward as the result of significant declines in coal mining, oil and gas extraction and metal mining (Table 2). Discussion of mine production is frequently segmented according to the type of materials produced within the broad categories of metals and industrial minerals (also known as nonmetallic minerals). Industrial minerals can be further subdivided as construction aggregates and other industrial minerals. Metals tend to have higher unit values but very low production quantities compared with those of industrial minerals, which have higher production quantities but are lower-valued materials, such as crushed stone or construction sand and gravel. Therefore, for discussion and analysis of the performance of the nonfuel minerals industry, the value of production is used rather than the tonnage produced. Tonnages of construction aggregates are orders of magnitude larger than those for most other mineral commodities thus making direct compar"

Jan 5, 2017

By U. S. Geological Survey Staff

"In 2017, the total estimated value of nonfuel mineral production in the United States increased by 6 percent from 2016 (Table 1). The value of metals produced domestically increased by 12 percent and the value of industrial minerals produced domestically increased by 3 percent. Some metal commodity values (cobalt, magnesium metal and palladium) increased by more than 35 percent in 2017 from 2016 owing to higher prices.Some U.S. metal mines and processing facilities remained idle in 2017, including three primary aluminum smelters in Indiana, Missouri and Washington; a titanium sponge facility in Utah and a byproduct vanadium production facility in Utah. In contrast, new gold mines opened in late 2016 and 2017 in Nevada and South Carolina, respectively, and iron ore mines in Michigan and Minnesota restarted or operated for the full year. In addition, increased oil and natural gas drilling activity led to increased production of some industrial mineral commodities that are used for oil and gas drilling. Production of some industrial minerals, especially those used in infrastructure and residential construction, remained essentially unchanged in 2017, a reflection of the limited growth in construction activity. The production of some metals, including iron and steel, aluminum and other nonferrous metals and nonmetallic mineral products increased. Overall, mining activity trended upward as the result of increases in coal mining, oil and gas extraction and metal mining (Table 2).Discussion of mine production is commonly segmented according to the type of materials produced within the broad categories of metals and industrial minerals (also known as nonmetallic minerals). Industrial minerals can be further subdivided as construction aggregates and other industrial minerals. Metals tend to have higher unit values but very low production quantities compared with those of industrial minerals, such as crushed stone or construction sand and gravel, which have higher production quantities but are lower-valued materials. Therefore, for discussion and analysis of the performance of the nonfuel minerals industry, the value of production is used rather than the tonnage produced. Tonnages of natural aggregates are orders of magnitude larger than those for most other mineral commodities, thus making direct comparisons based on weight meaningless (Fig. 1)."

Jan 5, 2018

By E. S. Forbus

A process for producing reductive bleach in-situ in kaolin slurries has been developed. The bleach is formed by mixing an iron sponge powder (-325M) with slurry treated with SO2. The process has been successfully demonstrated in production, and applied to several grades. The color, brightness, and viscosity of the bleached product is equivalent to or better than that of product bleached with commercial sodium hydrosulfite . The tested products can be bleached at a cost, which is 38-54% of those associated with the use of commercial bleach.

Jan 1, 1993

By D. J. Lachel, Douglas E. Hansen, Bruce Kennedy

The very high cost of exploration and development for new mines requires that a carefully planned, complete, and technically competent geotechnical evaluation be applied to the ore body and the surrounding rock. The ground conditions must be predetermined sufficiently so that, during the development and exploitation stages, unexpected conditions will be of minor consequence. Ground conditions are a major factor affecting the cost of excavated items such as shafts and inclines. For example, shafts cost less to sink in tight dry ground than in highly pervious ground below the water table, with all other factors being equal. The proper mining methods also is dependent upon the ground conditions. Bad ground for room-and-pillar mining may be ideal for caving methods; whereas, ideal ground for room-and-pillar mining would be extremely difficult for a caving operation. To do a proper engineering design, the parameters of strength, deformability, and permeability must be determined, in addition to the loads that will be applied as a result of the mining activity. The required degree of accuracy for each parameter depends upon the individual case. For example, the strength of massive rock in which openings of small cross-sectional area are to be driven at shallow depths needs to be resolved only within several thousand kilopascals (pounds per square inch). Under such conditions, the rock strength is not likely to be of great economic importance unless the rock is very weak. Large openings at great depths require a much more accurate appraisal of rock strength and deformation characteristics. Ground water conditions are important at any depth. Today, a number of techniques exist for evaluating conditions before opening up the ground for development. These techniques and their applications are described in more detail later in this text. The evaluation of ore body ground conditions should start at an early stage, as soon as the deposit has been proven viable for a mine. Economic geology investigations mainly serve to define the value and limits of the ore deposit. To do this properly, the geology of the site is determined in at least as much detail as is necessary to define the "controls" for the ore body. The ground-condition evaluation must determine the engineering properties of the ore body and the surrounding material. This includes the structural geology as it relates to rock strength; i.e., the frequency, extent, and orientation of discontinuities such as faults, joints, bedding, etc. Ground water conditions also must be determined. It is important that the detailed geology of the site be determined at an early date. Reasonable geotechnical parameters must be established during this time period, so they can be used in mining model studies that include both physical and mathematical models. The ultimate goal bf-the geotechnical evaluation is to predict the ground behavior as the excavations are made and how the ground behavior will affect the safety and economic well-being of the mine. The formulation of a ground-condition evaluation program should be planned carefully to determine the particular geotechnical parameters only in as great a detail as will have a bearing on the mine design. For instance, it is not necessary to make numerous triaxial tests in strong rock when the mining will be conducted within a few meters (feet) of the surface in a regime of gravity loading and an absence of tectonic stresses. Similarly, it is not necessary to invest large amounts of time and effort in the determination of joint strengths if the orientations of the joints are such that the failure could not occur along them. Generally, the determination of ore body ground conditions can be divided into four main steps: 1) The general and structural geology of the site must be determined; this is determined primarily during the economic evaluation. 2) The material behavior characteristics of the deposit and the vicinity must be determined. 3) The ground water hydrology of the deposit and the vicinity must be determined. 4) Miscellaneous ground support considerations must be established. Gross features are defined first, followed by a series of increasingly detailed investigations. Specifically, the geology study should start by utilizing techniques such as remote sensing, topographic map interpretation, geologic mapping, etc. After the gross features, such as major faults, have been delineated, the studies are directed toward defining the more detailed elements of jointing, rock strength, ground water hydrology, and other characteristics. This information is used to formulate an assessment of the strength of the ore body and the surrounding rock. Finally, all of the gathered information is integrated to make an assessment of the rock behavior in relation to the types of openings, the excavation methods, the support requirements, etc., that should be used for the rock conditions that are present. The mine design and the geotechnical assessment should be an iterative process. General conclusions about the rock conditions will dictate a type of mine plan. The specific mine plan then should be modified by specific geotechnical considerations. For example, an initial assessment may conclude that the ore body is strong and that a strong rock unit is present over the ore body. Thus, one definite possibility is to mine the deposit by room-and-pillar methods. However, subsequent investigations may reveal faults through the deposit, requiring relocation of the mine openings so that pillars and other structures are in sound rock. In other words, the final mine plan should be compatible with the geotechnical aspects of the ore body.

Jan 1, 1982

By James M. Barker

The borate deposits of Death Valley, first exploited in 1882, were a major world source of boron-bearing products until shortly after very large deposits near Boron, California (Kramer) came on stream in 1926. Borate mining in Death Valley then became moribund, with most extant deposits held as reserves backing Kramer. Tenneco began borate operations following acquisition of claims in 1967 and is the only active borate producer inside Death Valley National Mon¬ument. Borate ores, confined to the lower Furnace Creek Formation (early to middle Pliocene), initially precipitated in a shallow lake fed by boron-rich volcanic hot springs associated with the Basin and Range province. Later diagenesis and remobilization plus regional folding, faulting, and erosion altered and complicated originally simple borate mineralogy and distribution. Dominant ore minerals are ulexite (NaCaB509.8H20), probertite (NaCaB509.5H20), and colemanite (Ca2B6011.5H20). Tenneco currently operates two open pits near Ryan, California. Mining is by bulldozer-pushed scrapers hauling waste and front-end loader/off-highway truck combinations for ore and waste haulage. Archeological, environmental, and aesthetic considerations influence both mine plans. Boraxo Pit, opened in 1970, has deep ore (stripping ratio 10 to 13:1) which occurs along a fault and as beds in shale on the hanging wall. Problems include pit wall instability (adverse bedding), non¬ripable calcareous shale (11,000 fps), and mixed ore separation. Sigma Pit, opened in 1975, has shallow (stripping ratio 1 to 1). low dipping, bedded ore in shale. Massive ulexite and "granular" un- cohesive colemanite present problems in mining and milling. Colemanite is crushed to -6 inches, washed, dried at 350°F, then calcined at 800°F with 100 tpd capacity. Crushed (-6 inch) ulexite or probertite is Raymond milled to customer specifications with a capacity of 1000 tpd.

Jan 1, 1976

By M. Wasel

The Gross Rosebel gold deposits are located in the Guiana Shield of north central Suriname. Initial discovery of surficial gold in 1880 by local artisanal miners preceded small-scale mechanized mining from 1885 to 1939. The first systematic exploration program was carried out by Placer Development from 1974 to 1977. In May 1992 Golden Star Resources optioned the property. Initial shallow reconnaissance diamond drilling of the extensive surface geochemical anomalies intersected sporadic gold mineralization with no apparent continuity between drill sections. Successive deep augering, trenching and systematic grid drilling based on information from surface mapping allowed development of a preliminary geological model. Further drilling of specific structural-lithologic targets and more complete synthesis of geological data from the trenching and deep auger sampling added to the geological model and defined the multiple controls of gold mineralization. Carefully planned infill drilling on a tighter grid spacing resulted in progressive definition of reserves within six discrete gold deposits. In a complex geological setting, the key to success at Gross Rosebel was persistent, systematic exploration, detailed mapping, careful core logging and perceptive geological interpretation. Reserves now stand at 48.6 Mt at 1.6 glt Au, or 2.4 million ounces of gold. The purpose of this paper is to describe the progression of exploration activity that led to the definition of substantial gold reserves and to summarize the geology of the deposits.

Jan 1, 1998