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By William Gleason

"During the past nine years the number of cellular phones connected to a network has increased from 34 percent of the world’s population in 2005 to 93 percent in 2014. These phones are powered by a combination of materials including elements such as gold, silver, copper and rare earths. And, as more parts of the world become connected to networks, the number of phones being produced, and the elements they will need, will continue to increase. The demand comes as prices for these commodities are slumping and access to the commodities is getting more difficult, technically and socially.These mobile devices have connected people around the world in ways that could not have been imagined two decades before, and, ironically, this communication has strengthened opposition to the development of the mines that produce the very materials they need to operate.In his keynote address to the 2014 SME Arizona Conference at the JW Starr Pass Resort in Tucson, AZ, on Dec. 8, 2014, John O. Marsden, SME President and president of Metallurgium, spoke to more than 500 attendees about the challenge to produce the materials that society needs while at the same time challenging the general public’s perception of mining that is often inaccurate and less than favorable.Marsden highlighted the amount of raw materials that will be needed not just for phones, but also for things such as automobiles, including electric cars, as a way to illustrate the importance of mining. Even so-called green products such as Tesla cars, which require about 317 kg (700 lbs) of aluminum, 13 kg (30 lbs) of copper and 36 kg (80 lbs) of cobalt for their eco-friendly batteries, will need materials mining provides.These are some of the numbers that the general public is often unaware of. They are part of the necessary things that mining provides for society but are rarely reported on. Instead, it is the accidents like the tailings spill at the Mount Polley Mine in British Columbia and at the Buena Vista Mine (Sonora, Mexico) that grab headlines and stick in the minds of the public, adding more challenges to an industry that already has its own complex technical challenges to deal with."

Jan 1, 2014

By YONGQIONG YANG, Ning Wang, CHONGGUANG LUO, LI ZHU, Hanjie Wen, SHENGJIANG DU, Hannian Gu

Kaolin clay from Late Permian sequences has been considered a potential resource for niobium (Nb) due to high concentrations reported at several hundred micrograms per gram and large areal distribution. A previous case study identified titanium (Ti)-bearing minerals associated with kaolin clay as the main host phases for niobium. Correlation between the Nb and Ti concentrations was poor, however, and the types of Ti-bearing minerals and modes of Nb occurrence were unclear. To investigate this, typical kaolin clay samples from Late Permian sequences in southwest China were characterized, and final products derived from them were investigated using X-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDS). The results revealed three types of titanium dioxide (TiO2) mineral phases in the clay samples: (1) massive TiO2 minerals, (2) aggregates of nano TiO2 minerals and (3) granular TiO2 minerals. The first two did not contain niobium. From the EDS analysis, the granular TiO2 minerals, including anatase and rutile, were the source of Nb in the kaolin clay samples. 

By Chris Howell

PotashCorp?s Aurora phosphate mine, in Beaufort County, NC, operates four low pressure boilers and four high pressure boilers to meet its process steam requirements. Maintaining these boilers is critical to meeting production demands. Processing phosphate ore into phosphoric acid requires large amounts of sulfuric acid and steam. Ore is mined from the phosphate deposit with large bucket excavators after 9 to 30 m (30 to 100 ft) of overburden is removed. The phosphate ore is mixed with water to make a slurry that is pumped to the mill. Elemental sulfur is burned in the presence of air to make sulfuric acid. This process is highly exothermic and boilers produce steam while cooling the process. The phosphate ore is reacted with sulfuric acid and the resulting products are refined into different grades of phosphoric acid for fertilizers, feed stock and food additives. Plant operators at the mine were challenged with boiler feed water that was high in silica and other contaminants. As a result, boiler operations were experiencing difficult, labor-intensive operations and equipment deterioration. This resulted in higher operating costs and diminished processing performance. The facility was operating an aged boiler feedwater pretreatment system that included warm lime softening followed by pressure filtration and a cation/anion/mixed bed demineralizer system. The demineralizer required frequent regeneration and chemical usage was high and costs were difficult to predict. Depressurized well water (DPW water), used for plant utility water and boiler makeup, is very high in silica, in the range of 60-70 ppm. Silica can form scale at pressures below 600 psig. Above 600 psig, silica starts to volatize, carrying over with steam to potentially form deposits on downstream equipment and processes. Mine officials decided to upgrade the boiler feedwater pretreatment system to a state-of-the-art reverse osmosis (RO) membrane system. This new system, which started up in March 2009, has improved operating performance and reduced water consumption and overall operating expenditures.

Jan 1, 2011

By H. I. Meyer

The mine is a large open-pit copper mine located near Tucson, AZ. Mining operations involve shovels digging at relatively fixed locations and haul trucks moving the muck to a primary ore crusher, a primary waste crusher, and directly to waste dumps. The total investment in shovels and trucks is some $100 million. Fig. l is a schematic drawing of the operation. A static method of truck assignment is used; i.e., each driver is given one particular shovel to serve until reassigned by the dispatcher. A dynamic system is one where trucks are reassigned after each trip. The problem is to compute a near optimum assignment of trucks for efficient operation.

Jan 1, 1979

By Alafara A. Baba, Yakubu A. Dallatu, Kehinde I. Omoniyi, Shemang Y. Chindo, Edith B. Agbaji

With the rise in global demand for pure copper, there is an urgent need to consider the processing of low-grade chalcopyrite ores. Ammoniacal leaching solutions have been reported as effective and efficient leachants for the dissolution of chalcopyrite. This work reports on different parameters that influence the leaching kinetics of a Nigerian chalcopyrite-rich siderite ore obtained from the Wase local government area of Plateau state, Nigeria, and assayed as 11.30 weight percent copper.

May 1, 2023

By Liming Yuan, Isaac Zlochower, RICHARD THOMAS, Thomas H. Dubaniewicz, Teresa Barone

Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane (CH4)-air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) measured thermal-runaway pressures of lithium iron phosphate (LFP) cells as a function of free space within sealed enclosures and observed an inverse power relationship. A well-confined cell produced 4260 psia (294 bar) of pressure during a thermal runaway, far exceeding minimum pressure containment specifications for conventional explosion-proof enclosures. Results indicate that adding enough free space surrounding LFP cells can reduce thermal-runaway pressures to levels below that expected for CH4-air ignitions. Measured thermal-runaway temperatures were below the minimum autoignition temperature of CH4-air.

By H. Colijn

Feeders are used to provide a means of control for the withdrawal of bulk materials from storage units, such as bins, bunkers, silos and hoppers. This control function can only be performed properly as long as the bulk materials flow by gravity to the feeder in a uniform and uninterrupted fashion. A feeder can do many things, but it should never be considered a suction pump: During the past few years various papers have been written and presented on feeders and their application. 1,2,3,4,5,6,7,8,9)* It is not the intent of this paper to cover the same ground, and the readers are therefore ad¬vised to consult the referenced publications for supplementary information. This paper will be confined to some specific design criteria of bin feeders, such as feeder load and power requirements. Special attention is given to the basic design criteria of vibratory feeders.

Jan 1, 1968

By Robert W. Bruhn

The prediction of damage to a structure that is to be undermined is generally a two step process. First, the expected ground movements (the displacements, slopes, curvatures, and strains) are estimated using available (often empirical) predictive methods or survey data from a site of comparable geology, topography, and mining geometry. Second, the prospects for damage to the structure are assessed by comparing the expected ground movements to tolerable limits, some of which appear in the technical literature as damage criteria. The inverse problem of relating observed building damage to causative ground movements involves essentially the same elements. In either case, the usefulness of published damage criteria to subsidence problems may be limited in all but the most elementary cases. This paper considers several cases where structural behavior and site specific details had to be taken into account in assessing the relationship between damage and ground movements.

Jan 1, 1986

By C. S. Thompson, P. A. Ciullo

Pyrophyllite is a naturally occurring hydrous aluminum silicate with the molecular formula SiO,,AI,,(OH), or, as more commonly expressed, the oxide formula A120,~4Si02~H20. Pyrophyllite is rarely found in deposits as the pure mineral and is often intimately associated with quartz, sericite, kaolinite, and diaspore. These associated minerals, to a large degree, help determine the most appropriate commercial application for a given pyrophyllite ore. Structural similarities plus the generally soft platy nature of pyrophyllite has in the past caused it to be included with talc in applications and production data. The Minerals Yearbook, published annually by the US Bureau of Mines (USBM), still reports on talc and pyrophyllite together, although admitting that they do not share the same uses. Pyrophyllite has also at times been considered a clay mineral because of its structure and chemistry. The refractory properties of pyrophyllite have been known for nearly 200 years, but it has only been in the past 60 to 70 years that a variety of applications have been developed to exploit the unique characteristics of this mineral. Worldwide, pyrophyllite is a component of refractories, whiteware, foundry mold dressings, pesticides, paint, plastics, rubber, cement, fiberglass, and soap. Historical Overview The most salient refractory features of pyrophyllite are its low coefficient of thermal expansion, high thermal conductivity, low moisture expansion, and good resistance to corrosion by molten metals and basic slags. One of the first recorded uses of this mineral was as firebrick in Japan in the early 1800s. This followed its discovery in 1797 on Mount Omotoyama at the site of the present Mitsuishi mine. In addition to firebrick, sawn blocks of ore were used for carvings and in the manufacture of slate pencils and signature seals. The Mitsuishi mine is still one of Japan's largest. By the mid-1800s, refractories were being made in Japan from roseki (a pyrophyllite-bearing ore) for the construction of metal melting furnaces. The mineral did not get its name until 1829 when R. Herman, testing a sample of supposed talc from the gold-quartz veins at the Berezovo deposit in the Urals, showed that it was actually an aluminum silicate and designated it pyrophyllite. This name was derived from the Greek pur for fue and phullon for leaf, in allusion to the effect of heat in causing separation of the laminae in foliated varieties (Mellor, 1927). The exact date of the discovery of pyrophyllite in the United States is uncertain, but it is believed that the talc and soapstone deposits noted in an 1827 report on the geology of the slate belt of North Carolina were actually pyrophyllite occurrences (Olmstead, 1827). Pyrophyllite was first used in North Carolina on a local basis in the early 1800s. Blocks were sawn and cut for use as stove linings, mantels, chimneys, fireplaces, and gravestones. This was the material of choice because it did not shrink when heated, but cut easily and hardened as it weathered. Pyrophyllite crayons were sold commercially by local gold miners for steel marking and as tailor's chalk from about 1800 until 1922. It was during this period that pyrophyllite was discovered near the town of Hemp (later renamed Robbins), NC. The large quantity of scrap resulting from the sawing of crayons at this deposit prompted the construction in 1921 of a grinding plant. The ore scrap was ground to fine granules and sold to asphalt producers to prevent shingles from sticking together. By the mid-1930s, milled pyrophyllite from North Carolina was also being successfully utilized by the ceramics industry in whiteware for its low cost and ability to shorten firing time. Also during the 1930s, pyrophyllite was first used in kilncar furniture in the United States. Canada was another early entrant in the pyrophyllite business. Mining at the Foxtrap deposit on the Avalon Peninsula of Newfoundland began in 1904, with ore shipped to the United States. Production from this deposit was mostly sporadic in the ensuing years until 1956 when mining began for shipment and captive use in US tile manufacture. This production has remained continuous and still essentially captive to the present. The Foxtrap deposit is currently the sole commercial source of pyrophyllite in Canada.

Jan 1, 1994

By M. G. Gorman

The effects of particle size, particle shape and degree of aggregation on n-dodecylamine flotation of -20 µ m quartz and glass beads were studied. A microflotation cell suitable for use with very fine particles was used in the flotation experimentation. Degree of agglomeration of particles was estimated by comparing size distributions of the quartz and beads in a dispersed system to size distributions in systems in which the collector was present. Results obtained show that in such flotation systems the fine particles are not generally present as individual particles during flotation but rather as aggregations. However, the quartz floats more readily than the beads indicating that there are some shape effects in the systems, considering the large specific surface areas of the materials it also appears that substantial amine consumption in the systems may limit flotation or lead to a requirement of greater reagent dosage for equivalent flotation to that tor larger particles.

Jan 1, 1990

By John E. Husted

Universities have education as their primary purpose. This appears to be an innocuous statement with simple meaning. In an age of conflicting semantics, however, cords and meanings are often lost or changed. The term education is often broadly expanded to encompass any form of learning process, or the accumulation of knowledge, and even to the beneficial application of knowledge to man's problems, hence one find that education in universities is not solely the formal process of texts, lectures, recitations, and testing by a batch process known as class room teaching. Despite critics of education batch is spelled with an "a", instead of an "o" - at least we hope so If one defines teaching as causing to learn, then the learning objectives may necessitate a variety of approaches within the teaching concept and research is among those favored at the graduate and some undergraduate levels. Research has been among the glamour words and certain fields such as oceanography and space science have had more than their share of glamour. Unfortunately, industrial mineral research has not had the competitive drawing power of enamoring students of the "note" generation in terms of glamorous accomplishment. Research today usually requires sophisticated equipment and such equipment is expensive, both for initial purchase and operation. Again, administrations, be they industrial, government, or academic, usually require

Jan 1, 1970

By D. H. Stonehouse

There is no such thing as an industrial minerals industry. There are, however, many industries operating in the general field of industrial minerals. And although we use the phrase "industrial minerals industry" out of sheer convenience, the only common denominator among, say, the potash mining and processing industry, the sulphur-sulphuric acid industry and the granite industry is, in fact, that they each are exploiting an industrial mineral resource. May I quote the person whom I consider to be the reigning Mr. Industrial Minerals, Robert L. Bates, who in the 4th edition, 1975, of Industrial Minerals and Rocks states: "An industry is considered to belong to the industrial minerals field if its operations consist of extraction and processing, but not manufacturing. Thus the mining and beneficiation of feldspar is a mineral industry, but the manufacture of ceramic products is not. In the cement and lime industries, processing merges into manufacture, and the line is less distinct. It disappears altogether in a plant that extracts salt as artificial brines, and makes sodium and chlorine chemicals, all under the same roof."

Jan 1, 1981

By M. R. Rosen

A technique is presented for simple characterization of the performance of flocculents in various mining applications. The method utilizes three key parameters obtained from raw settling data and combines them into a single athematical parameter called the desirability coefficient. The first two parameters are the timesrequired for the slurry-supernatant interface -to fall to two selected fractions of the starting height, and the third is the clarity of the supernatant liquid. The relative values of the three parameters may be assigned different weights in order to make them correspond with laboratory and field performance requirements of a particular industry. Provision is also made of an, internal comparison of test flocculant data with that of a control.

Jan 1, 1980

By Gary Brierley, Lok Home

"The majority of tunnels for civil engineering applications are now being constructed using some form of mechanical excavation. Beginning in the 1960s with rock tunnel boring machines (TBM), the tunneling industry has introduced both earth pressure balance (EPB) and slurry pressure balance (SPB) soil machines; mixed soil and rock machines and a variety of different mechanical devices for the construction of small diameter tunnels. Over time, these machines have become more powerful and more adaptable to a wider variety of ground conditions; so much so that tunnels are now being constructed in ground conditions and in the vicinity of third-party impacts that would have been considered beyond the state of the art just 10 years ago. Figure 1 is an example of a mixed ground crossover TBM used successfully at Mexico City’s Túnel Emisor Poniente II.All of the above is highly advantageous for the tunneling industry, but it has also placed a much higher level of risk on the performance characteristics of the tunneling machines, on the contractors operating those TBMs and on the manufacturers of those machines. Most of the risks for a tunneling project are associated with creating the space inside of which the finished facility will be constructed. In order to create that space, the tunnel contractor must make many decisions about the best way to excavate the ground, the best way to control the ground at the face of excavation and the preferred method for supporting the ground around the tunnel in a manner that is safe for the workers and stable with respect to all of the overlying and adjacent existing structures. If it is proposed to use some form of TBM in order to build the tunnel, then the TBM becomes central to all three of these activities and becomes an integral part of managing the risks associated with these activities."

Jan 9, 2018

By NICHOLAS BELLUSCI, D. Erik Spiller, Patrick R. Taylor, VICTOR BRAMAN

Approximately 30% of the world’s production of soda ash comes from mining and processing of naturally occurring deposits of sodium carbonate containing species. Of these deposits, the largest and most profitable have been the trona beds found near Green River, Wyoming. Processing of trona ores is water-energy intensive, particularly due to unit operations of calcination, dissolution, and evaporative crystallization to wield a high-quality dense soda ash product and reject the insoluble gangue species, primarily in the form of oil shale. However, it is speculated that the glass-manufacturing industry, the largest consumer of soda ash, may be able to use a product of a lower grade and consistent level of the insoluble constituents. Thus, pre-concentration of trona ore was investigated using sensor-based sorting, to produce a beneficiated trona stream that would be fed to calcination. The study encompassed preparation of a run-of-mine (ROM) Green River ore sample, selection of 25–75-mm-sized specimens, imaging of the specimens by x-ray transmission (XRT), color, and laser-induced fluorescence (LIF)-based sensors, insoluble analysis of the specimens, and a bench-scale sorting test. Results of the study established that a correlation between the color of the individual ore particles and their insoluble content existed and that a surface detection-based sensor, particularly LIF, was apparently more suitable than XRT to produce a beneficiated trona stream. The bench-scale sorting test demonstrated that a 65% separation efficiency and a 70% recovery of trona could be achieved.

Aug 9, 2022

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

In early March 2011, a 6.2 m (20.3 ft) diameter Rob-bins Double Shield tunnel boring machine (TBM) crossed the finish line in Sochi, Russia. The machine completed a 4.5-km- (2.8-mile-) long section of tunnel that will ultimately become part of the transportation infrastructure for the 2014 Winter Olympic Games. The TBM advanced through difficult ground at aver-age rates of 100 to 120 m/week (330 to 390 ftpw) for contractor OJSC Bamtonnelstroy, a division of the SK Most Company. The section of tunnel will ultimately become a service tunnel for Complex #3 - a section of Sochi?s transportation infrastructure under construction, which includes road and rail tunnels. A second, 10 m (32.8 ft) diameter Robbins Double Shield TBM is currently excavating the parallel 4.6-km- (2.9-mile-) long main railway tunnel using a continuous conveyor system for efficient muck removal. A 13.2 m (43.3 ft) diameter highway tunnel is also under construction. The 6.2 m (20.3 ft) Robbins TBM achieved high rates despite difficult conditions. The tunnels run through mixed ground including massive to completely fractured limestone with clay seams. Some sedimentary rock including sandstone and siltstone is present, along with fault zones consisting of breccias and conglomerates. In May 2010, the machine was stopped after encountering a significant fault zone consisting of broken rock and running soft ground. Field service personnel and crew successfully freed the machine by excavating a bypass tunnel around the TBM, freeing the cutterhead. Following the restart, a combination of continuous probe drilling and ground treatment with cement silicate and foam kept the machine moving forward.

Jan 1, 2011

By J. Brad Dalton, Sam Vance, Trude V. V. King, Roger N. Clark, Raymond F. Kokaly, Gregg A. Swayze, Dana J. Bove

Visible-wavelength and near-infrared multispectral image cubes for the Animas River Watershed from Hermosa, Colorado to the headwaters at Animas Forks, Colorado were acquired on June 18, 1996 using the Jet Propulsion Laboratory's AVIRIS (Airborne Visible and InfraRed Imaging Spectrometer) instrument (Green et al., 1998). These image cubes have been analyzed using the USGS Tetracorder V3.4 implementation (Clark et al., 1995), an expert system which utilizes a database of more than 300 laboratory spectra of endmember minerals and mineral mixtures to generate maps of mineralogy, vegetation coverage, and other material distributions. Major iron-bearing, clay, carbonate, and other minerals were identified along with several minerals associated with acid-generating hydrothermal systems including pyrite, jarosite, alunite and goethite. Additionally, distributions of alkaline minerals such as calcite and chlorite indicate a relation between acid- buffering assemblages and stream geochemistry within the watershed.

Jan 1, 2000

By David J. Akers

INTRODUCTION The variety of uses of coal and the wide range of characteristics of coal combine to produce a need for a wide variety of laboratory analysis. Coal is used to heat homes, produce electricity, and make coke for steel manufacture. It can also be used to produce both gaseous and liquid fuels as well as a variety of chemical products. Various applications may require specialized analytical procedures. For example, some of the procedures developed for the coke industry, such as expansion or contraction during carbonization, have little value to the power generation industry. Even for a single application, the type of analysis needed can depend on the source and/or general nature of the coal. This section provides a general overview of the types of analytical procedures commonly applied to coal from the perspective of the user of this information, not the producer. The intent is not to detail laboratory procedures, but rather to discuss the application of commonly used laboratory tests in coal preparation. Accordingly, laboratory procedures are categorized by type of information produced. Gravimetric Analysis Procedures that produce weight-based information (parts per million, pounds per cubic foot, or weight percent). Such analyses can relate to the coal's physical, chemical, or mineralogical characteristics. Volumetric Analysis Procedures that produce volume-based information (amount of a mineral present as a volume percent). The primary source of volumetric information is from petrographic analysis. Application Tests Procedures that measure some characteristic of coal that has been empirically related to some application or handling or processing step. Typically, these procedures attempt to duplicate some aspect of the commercial application at laboratory scale and may produce information in the form of an index. Applications procedures do not measure a single component of the coal but infer the combined effect of multiple components. Each class of information is discussed in the order listed. References are provided as a source of more detailed information. The American Society for Testing and Materials (ASTM) publishes the most inclusive reference to analytical procedures. This publication,16 which is revised annually, provides extensive information concerning generally accepted methods of laboratory analysis. ASTM also provides standards for sampling and some information concerning sample handling.

Jan 1, 1991

By Dave Southworth

After Abe Lee discovered gold (in April 1860) near the site of present-day Leadville, Colorado, he and is group staked nearly all of California Gulch with "speculative claims." They did so in an effort to grab any property that might be potentially profitable. But the plan did not work. New prospectors demanded a miners' meeting, from which arose the official "Bylaws of California Mining District, California Gulch, Arkansas River." These bylaws, adopted on May 12, 1860, established provisions as to the number, size and type of claims that could be filed. Fair laws invited more newcomers. By mid-summer, 5,000 people with tents and wagons were scattered from one end of the gulch to the other.Among the earliest arrivals to the region that spring were Horace Austin Warner Tabor and his wife, Augusta. H.A.W. Tabor, who was to become a pillar in the development of Leadville, arrived at California Gulch during a food shortage. He sacrificed his oxen so that hungry miners could eat. By doing so, he immediately became the friend of many. Augusta established a little store where she sold her baked goods and provided meals. Like most of the men, Horace prospected the surrounding hills. He only did so, however, for a short time. California Gulch yielded more than $5 million in gold during the next five years. By 1866, however, the placer gold was gone and most of the miners had packed up and left. Charles J. Mullen and Cooper Smith, who were grubstaked by a Philadelphian named J. Marshall Paul, found a new, rich lode at the Printer Boy Mine in 1868. It was the first underground gold mine in the Leadville area and marked the transition from surface mining to underground hard rock mining. Its discovery created a new but modest flurry of activity. Heavy black sand covered the region and made gold mining difficult. In 1875 William Stevens and Alvinus Wood decided to have the sand assayed. They discovered that it contained 15 ounces per ton of silver and was rich in carbonate. Stevens and Wood kept their find a secret for nearly two years. When the word spread in late 1877, the silver boom was on. In 1878 prospectors, merchants and others trickled into town from all directions. Dr. David H. Dougan closed his office. in Alma, crossed Mosquito Pass and set up shop in Leadville. Nobody seemed to need a doctor, however, and Dougan sat in his office for 28 days without a customer. On the 29th day he received word that there had been a mining accident and he was needed immediately. -That was the begin¬ning of his illustrious career in Leadville. Dougan was a successful physician, became mayor in 1881 and was later president of the Carbonate National Bank. Leadville was a simple community of log structures in 1878. By June of the following year, however, it had blossomed considerably. According to Cass Carpenter, as of May 1,1879, Leadville had "...19 hotels, 41 lodging houses, 82 drinking saloons, 38 restaurants, 13 wholesale liquor houses, 10 lumber yards, 7 smelting and reduction works, 2 sampling works for testing ores, 12 blacksmith shops, 6 livery stables, 6 jewelry stores, 3 undertakers and 21 gambling houses where all sorts of games are played as openly as the Sunday School sermon is conducted." Additionally, there were 36 brothels. When George E. King and other architects arrived, Leadville took on an air of elegance and sophistication. In sharp contrast to some of the Victorian-style, gingerbread-laced homes in Leadville, its suburbs were comprised of many tenement shacks and plain cabins mixed with a few commercial buildings, many mines and smelters. Mines sprinkled the area east of Leadville like pepper from a pepper shaker. Wherever there was a cluster of mines, a camp usually sprang up. Most were very close together. South of Leadville the giant Arkansas Valley lead smelter sprawled out between Stringtown and Bucktown in an area known as Smelter Valley. Founded in 1879 as the Billing and Eilers Smelter, the Arkansas Valley plant was operated by the American Smelting and Refining Company. Several other smelters operated in the vicin¬ity. In April 1878, Horace Tabor grubstaked prospectors August Rische and George Hook. For $64 worth of supplies and tools, he was guaranteed a one-third interest in their findings. Rische and Hook discovered the Little Pittsburg (often spelled Pittsburgh) Mine and made Tabor an instant millionaire. Tabor once purchased a "salted" mine, the Chrysolite; but instead of considering it a bad deal, he further developed the property and struck rich silver ore. Later, Tabor purchased the Matchless Mine for $117,000, possibly the only investment he made without partners. During its peak years, the Matchless yielded $1 million worth

Jan 1, 1998