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By Robert C. Collins, Clifford L. Jewett

The development and production of artificially colored roofing granules have been key factors in the success of the asphalt roofing industry. They provide protection for the asphalt from solar radiation and satisfy the home-owner's desire for a wide range of attractive colors. As a result, the asphalt shingle has become the most commonly used roofing material today. In addition to providing a stimulus to the asphalt roofing industry, artificial methods of coloring granules completely changed the nature of granule production from one of quarrying, crushing, and screening to a complex technical operation. Today's roofing granules are the result of many years of research, and they are produced in modern plants to exact specifications. History Asphalt roofing materials available today are the product of a long evolution of technological development. Forerunners of the present bituminous products, appearing as early as 1780, were primitive constructions of burlap saturated with crude tar or pitch. An early improvement to this basic effort was the dusting of talc, mica, or other finely ground material on the coated surfaces to keep the roofing from sticking to itself in storage. At times some pigmentation was added with the dusting material for initial color, but this was far from satisfactory. In fact, this early product possessed none of the qualifications of a good roof surfacing material. It was not economical; it was difficult to handle and apply; it was not attractive; it provided no resistance to fire; and it would not withstand the elements as well as other products then in use. Methods and machines were soon devised to saturate endless webs of felt with asphalt from the fast-growing petroleum industry. Even though saturated felt became available, this product of rags and wood fiber had almost the same limitations as burlap and tar. Even with heavier coatings of asphalt applied to both sides of the sheet for rigidity and longer life, the product still lacked color and fire resistance. Further, it was found that constant exposure to the sun soon caused the asphalt to become brittle, and it eventually cracked and leaked. This led to the first important use for crushed mineral products on asphalt-coated shingles and provided the key to the subsequent growth of the asphalt roofing industry. When a layer of crushed mineral was embedded in the surface exposed to the weather, the asphalt coating was protected from ultraviolet light and retained its elasticity over a much longer period of time. In addition to this protection, the mineral surfacing provided some resistance to fire. Fire resistance in the past had been found only in the expensive slate or tile roofs and the unattractive and expensive metal roof coverings which were then available. The most common mineral granule applied to the early asphalt roofing products as they began to make their first significant advances after 1900 was screened waste from slate quarries. Slate granules being available in dull shades of red, green, black, purple and a few other miscellaneous colors did provide a degree of color. Since slate has a flat platelike cleavage, it provides a cheap protective cover for the asphalt-coated sheets. Records show that coarse slate screenings were used for asphalt roofing as early as 1906. As the asphalt roofing industry developed, many other natural colored rocks and minerals were used to coat the surfaces of the roofing. The list included silica

Jan 1, 1975

By A. S. Learoyd

THE Anthracite Division, Bureau of Distribution, of the United States Fuel Administration, came into existence about Oct. 20, 1917. There had been no definite policy determined upon and the distribution had been carried out by the producers and distributors of this fuel as under normal conditions. The domestic sizes had been shipped from the beginning of the coal year on Apr. 1 in about their usual proportions to the various sections of the anthracite consuming territory of this country, which, in a general way, extended as far west as Nebraska and Montana, and in the south along the Atlantic seaboard to Florida. With the advent of cold weather, about the middle of November, acute shortages commenced to develop all over the northeastern section of the country, due to largely increased demand by the public in general, to enormously increased population in centers where industrial war activity was concentrated, and by the needs of the war industries themselves. Commencing with the early part of December, this demand was aggravated by extreme low temperatures and heavy snow; and the production decreased for the same reasons. From that date until the change in the weather, about the latter part of February, it was simply a question of getting coal into communities as emergencies occurred, to take care of individual cases. No definite plan of distribution could be followed. The coal mined between Apr. 1 and Nov. 1 had been distributed as mined and, therefore, only current production was available for distribution. The Anthracite Division, during this period, consisted of a Director, two assistants, together with an office force of seven or eight clerks and stenographers.

Jan 8, 1919

Cecil John Irving was born on 13th March, 1902. He was educated at King Edward's School in Birmingham, and at the University of Birmingham, where he graduated in B.Sc. Mining Metallurgy in 1922, and in B.Sc. Metal Mining on 7th July, 1923. Johannesburg 1986 The biggest mining exhibition ever held in Africa and several allied international conferences are to be staged in Johannesburg in September of next year.

Jan 1, 1985

By Gunnar Thaning, Goran Mathisson

The iron ores mined by LKAB in the north of Sweden have excellent beneficiation properties. This gives LKAB a favorable position as regards the production of low silica pellets for direct reduction. LKAB has concentrated on developing and marketing grades of pellets for the Midrex-Purofer-HyL process group, i. e., such direct reduction processes carried out in a shaft furnace or a static bed using reformed natural gas as a reducing agent. The paper deals with properties and quality demands of iron ore pellets for such processes. Matters such as the effect of the residual magnetite in the fired pellets on the degree of metallization, the amount and composition of the slag phase in the pellets, the mechanism of the disintegration during reduction, the state of swelling of the pellets during the conditions prevailing in these processes, the importance of the porosity, the improvement of the reducibility and lowering of the sticking tendency of the pellets by small additions of suitable additives, and the influence of the pellet size are discussed. A special test procedure for direct reduction pellets has been elaborated by LKAB. Thus, three metallurgical properties are routinely determined separately, namely reducibility, reduction strength, and sticking. The test methods are described. Finally the present and future LKAB pellets for direct reduction are presented with respect to chemical analyses and metallurgical properties.

Jan 1, 1980

By R. J. Dippenaar

In his inaugural lecture (delivered in Afrikaans at the University of Pretoria on 16th February, 1995), Professor Dippenaar defends his doctrine, philosophy, objectives, and methodology, as was required of a newly appointed professor in the days of old. Briefly, he recounts the growth and achievements of the Department of Material Science and Metallurgical Engineering at the University of Pretoria; he sketches its strategic guidelines and the obstacles encountered; he outlines the opportunities for the metallurgical industry in South Africa and the need for environmental control; and he describes how modeling techniques, together with expert systems, can aid both the industry and the community. He ends on an optimistic note, saying that his Department will continue to strive to transform adversities into opportunities, and to give its students a view of new horizons beyond the foundations laid by their teachers.

Jan 1, 1996

By Edgar Blanco

A thermodynamic and experimental investigation to develop a new process for converting molybdenite concentrate to molybdenum dioxide by a water-vapor oxidation process was carried out. In addition, the behavior of rhenium and selenium in molybdenum concentrate during the process was investigated. The kinetics of the reaction were determined by measuring the weight change of a sample with time in water vapor at temperatures between 700-1000°C. The results were analyzed by a Shrinking Unreacted Core model under chemical reaction control, which showed an activation energy value of 102 kJ/mol. To determine the behavior of rhenium and selenium, their concentrations in the molybdenum sulfide and the product molybdenum dioxide were measured by the use of ICP. While most rhenium remained with the molybdenum dioxide after the water vapor oxidation, almost all selenium volatilized. These results agree with thermodynamic analysis.

Jan 1, 2006

By Robert B. Parsons

"The Province of Manitoba tabled a Budget on March 11, 1992, which contains some important new initiatives designed to improve the fiscal environment for mining in the province. In addition, the Minister of Energy and Mines has released details of the Mineral Exploration Incentive Program which was originally announced in the 1991 Budget.Introduction""We recognize the important contribution o f mining to the economic activity of our province, including direct and service jobs and export earnings. We are determined to secure its future."" - The Honourable Clayton Manness, Minister of Finance, Province of Manitoba, March 11, 1992.With these words of introduction, Manitoba Finance Minister Clayton Manness announced a number of significant measures aimed at improving the fiscal regime for exploration and mining in Manitoba. At the same time, details of the Manitoba Mineral Exploration Incentive Program (MEIP) were released."

Jan 1, 1992

By Sally Lynn Zadra

"In May, 1994, Echo Bay Minerals - McCoy/Cove Mine petitioned for approval to recycle used oil formanufacturing ANFO. Recycling oil in this way will result in a cost savings for the minesite as well ashaving a positive environmental effect The petition has met the approval of the Bureau of LandManagement, the Nevada Department of Environmental Protection, and has received tentative approval from the Mine Safety and Health Administration."

Jan 1, 1996

By P. H. Shipway, D. G. McCartney, H. Saghafifar

The microstructural changes during thermal ageing at 650ºC in the interfacial region of Alloy 625 weld overlay on a 2.25Cr-1Mo steel was evaluated. Optical microscopy, scanning electron microscopy in SE and BSE modes, electron probe microanalysis and hardness mapping were used to characterize as-welded microstructure and its changes during thermal ageing and precipitates of interfacial region. Carbon migration across the interface was recognised as a major issue. A region of 300 µm wide adjacent to the fusion line, which was found harder in the as-welded condition decarburized during thermal exposure. Studies revealed that this region transformed to a soft region containing large ferrite grains and micron-sized carbides. In the weld overlay, a 50 µm wide hard band (over 650 Kgf mm-2) adjacent to the fusion line formed and carbide precipitates were observed along grain boundaries. Carbide precipitation mostly occured in the 150 µm wide region close to fusion line.

Jan 1, 2017

By B. P. Gilbertson

In her wonderful book, 'The Guns of August', historian Barbara Tuchman tells us that the French war plan for 1914 was dedicated entirely to an offensive strategy, not a defensive one. Plan 17, as it was called, concentrated everything on a French advance to the Rhine, leaving the French left virtually unguarded. This strategy could only be justified by the fixed belief that the Germans could not deploy sufficient manpower to extend their invasion around through western Belgium and the low provinces; and this in turn was based on the belief that the Germans would never use reserve troops in the front line. Al evidence to the contrary was ignored. But when the war came, the Germans followed Count Von Schlieffen's plan; they did use reserves in the front line and they did come the long way around on the west. The result- as you know-was a protracted war, with fearful consequences for the rest of our century.

Jan 1, 1994

By P. Whincup, T. Showell, B. Marchant, R. Dunne

An oversupply of copper on world markets in the early 90' s, coupled with a decrease in demand, resulted in a "tight" market for the sale of copper concentrate. In these conditions small producers of low grade copper concentrates found it difficult to sell their products. The situation was exacerbated for those producers also having reasonable quantities of penalty elements (e.g. As, Bi). The Telfer Gold Mine bulk copper gold concentrate, produced from treating underground sulphide ore, fell into this category (i.e. 16% to 20% copper, 30% to 35% sulphur and 3500ppm to 4500ppm arsenic). The concentrate sulphide minerals are predominately chalcocite and pyrite. Although a higher grade copper concentrate was attainable a substantial decrease in gold recovery ensued. Under the prevailing market conditions a decision was made to stockpile concentrates pending either an easing of market conditions or alternatively finding an on site method for treating the concentrate to recover both the contained gold and copper.

Jan 1, 1995

By Manlapig EV, Mackinnon IDR, Laudr DW

Orebodies at Ok Tedi contain a number of different fluorine bearing minerals. Some of these minerals report to concentrate and are responsible for the presence of the penalty element, fluorine, within the concentrate. Previous analytical work has tended to examine geological samples for content, rather than determine the metallurgical behaviour of the different mineralogical species. This investigation utilised X-Ray Diffraction combined with Scanning Electron Microscope / Electron Microprobe to identify the fluorine bearing minerals in flotation test products. Seven fluorine bearing minerals were identified, viz., talc, phlogopite, amphibole (tremolite and actinolite), sphene, apatite, biotite and clay. Talc was found exclusively in the skam ore type. Phlogopite and amphiboles (tremolite and actinolite) were found to occur in both skarn and porphyry ores, while sphene, apatite, biotite and clay were found only in the porphyry ores. Of the fluorine bearing minerals observed, only talc exhibited natural hydrophobicity to any significant degree. Phlogopite and the amphibole minerals were found to be hydrophillic, whilst the remaining minerals occurred in insufficient quantities to determine the flotation behaviour. Ok Tedi copper concentrate fluorine content prior to skarn ore treatment in the mill (typically 350ppm) was previously identified as deriving from phlogopite, while talc was believed to be the source of intermittent high concentrate fluorine contents when skarn ores were treated. This paper provides supporting evidence for this belief, and reports the nature of fluorine bearing mineral flotation behaviour.

Jan 1, 1997

By Thomas L. Barkley

My historic auditing of Underground Drilling and Blasting Practices has demonstrated to the author the need for reviews of many mines' procedures in these processes. Poor understanding of the basic principles and practices of the drilling and blasting science in Underground Development Mining has created significant costs to mining operations in many instances.

Jan 1, 2019

By Maria I. De Rosa

Table 55 and figure 19 show the number of fires and fire injuries for stone mills by state during 1990-2001. Table 55 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 118 fires occurred in 33 states. Seventy-six of the fires caused 82 injuries (including 8 fires and 6 injuries involving contractors). The yearly average was 9.8 fires and 6.8 injuries. The Ewhr value was 873 x 106 hr (In = 0.019), and the LWD value was 1,911. Missouri had the most fires (16 fires and 9 injuries), followed by Pennsylvania (15 fires and 14 injuries), Michigan (9 fires and 5 injuries), and Virginia (7 fires and 5 injuries). Of these states, Virginia had the highest injury risk rate value (In = 0.09 1). Table 56, partly illustrated in figure 20, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries decreased during most of the periods, with a sharp increase during the last period. The number of employees' working hours increased throughout the periods. The In values follow patterns similar to those shown by the injury values. Tables 57-63 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 21 shows the major variables related to fires for 1990-2001. Table 63 shows the fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By H. J. Chalmers

"Since the advent of large volume flotation machines, Cominco Ltd. has actively studied possible application of such machines to their various milling operations. A number of installations have been made and more are on the drawing board. This paper gives a description of these units, information as to choice of equipment, and information as to operating experience. Mechanical and operating details of six installations are summarized. Three different types of machines are discussed.Pine PointThe original Pine Point zinc flotation circuit comprised conventional roughing with two stages of cleaning. Over the years with increase in feed tonnage there have developed two adverse conditions; namely, a reduction in zinc concentrate grade coupled with an increase in MgO in the concentrate. This resulted in higher freight payments along with more severe smelter penalties. An intensive test program, in 1971, showed that the concentrate grade could be raised by 1.5 units of zinc along with a reduction in MgO from 0.8% to 0.47.. Subsequently this was done by adding two additional stages of cleaning using 16 cells of Denver 200-V's. The project was completed in January 1973 at a cost of $510,000 to give an estimated annual savings of about $390,000.Selection of the Denver Model 200-V was based on minimum floor space requirement, availability, and favourable operational and maintenance experience with Denver 100’s. As it happens it was possible to ""shoe-horn"" the 16 cells into place with a minimum of plant alteration. Some problems have been encountered with a tendency to ""sand up"" at high pH, particularly at the corners. Otherwise operational service has been very good."

Jan 1, 1974

By H. Rush Spedden

Antoine M. Gaudin was a vigorously creative man and throughout his career an internationally respected leader of his chosen profession of mineral engineering. To his professional colleagues and clients and to his former students he was both "Professor Gaudin," their wise, inspiring, and enthusiastic teacher, and "Tony," their, warm and beloved personal friend. Thus, his teachings and his unique inquisitive-creative approach to problems live on and grow in the accomplishments of his students. Antoine Gaudin was born at the turn of the century in Smyrna, Turkey, where his father was general manager of a French-owned railroad. It was there that he spent his earliest years, literally in the shadow of classic marbles from diggings at the site of Aphrodesias, which his father had rediscovered. From this, Tony developed an appreciation of the arts. He eventually surrounded himself with art treasures; he reveled in the beauties of nature, and he cherished his choice collection of rhododendron and azaleas. His artistic traits led him to take up painting when his daughter, Elinor, sought his help in blending her tints for a water color. In typical fashion he was not satisfied until he had become adept with pastels in capturing the muted tones of distant landscapes and the technical properties of light and color. Unfortunately not many paintings were produced. His paternal grandfather was Marc-Antoine Gaudin, for many years secretary of the Academie des Sciences in Paris, and a well known chemist and mineralogist whose primary interests included the synthesis of precious stones. In an autobiographical sketch written in 1939, Dr. Gaudin recalled: "As a child I saw many of the original synthetic sapphires and rubies which my father had inherited. This, coupled with my father's avocation of mining ventures and archaeology, early decided that I would become connected with the mineral industry." One can speculate that the archeological activities of his father, the mineral systhesis experiments of his grandfather, and his own early studies of mineralogy and geology formed a base from which his special talents as an experimentalist were to develop. Laboratory research under Professor Gaudin's personal guidance was often an intensive, fast-moving, and exciting experience--especially to a new graduate student. First of all, Professor Gaudin was a highly skilled observer with seem-

Jan 1, 1976

By Rush H. Spedden

Antoine M. Gaudin was a vigorously creative man and throughout his career an internationally respected leader of his chosen profession of mineral engineering. To his professional colleagues and clients and to his former students he was both "Professor Gaudin," their wise, inspiring, and enthusiastic teacher, and "Tony," their warm and beloved personal friend. Thus, his teachings and his unique inquisitive-creative approach to problems live on and grow in the accomplishments of his students. Antoine Gaudin was born at the turn of the century in Smyrna, Turkey, where his father was general manager of a French-owned railroad. It was there that he spent his earliest years, literally in the shadow of classic marbles from diggings at the site of Aphrodesias, which his father had rediscovered. From this, Tony developed an appreciation of the arts. He eventually surrounded himself with art treasures; he reveled in the beauties of nature, and he cherished his choice collection of rhododendron and azaleas. His artistic traits led him to take up painting when his daughter, Elinor, sought his help in blending her tints for a water color. In typical fashion he was not satisfied until he had become adept with pastels in capturing the muted tones of distant landscapes and the technical properties of light and color. Unfortunately not many paintings were produced. His paternal grandfather was Marc-Antoine Gaudin, for many years secretary of the Academie des Sciences in Paris, and a well known chemist and mineralogist whose primary interests included the synthesis of precious stones. In an autobiographical sketch written in 1939, Dr. Gaudin recalled: "As a child I saw many of the original synthetic sapphires and rubies which my father had inherited. This, coupled with my father's avocation of mining ventures and archaeology, early decided that I would become connected with the mineral industry." One can speculate that the archeological activities of his father, the mineral systhesis experiments of his grandfather, and his own early studies of mineralogy and geology formed a base from which his special talents as an experimentalist were to develop. Laboratory research under Professor Gaudin's personal guidance was often an intensive, fast- moving, and exciting experience--especially to a new graduate student. First of all, Professor Gaudin was a highly skilled observer with seem-

Jan 1, 1976

By F. F. Schmidt, H. R. Ogden, E. S. Bartlett

Continuing tantalum alloy development studies have been concerned with a more detailed investigation of promising binary, ternary, and more complex tantalum alloys containing Groups IV-A, V-A, VI -A. VII-A, and VII-A metal additions. A primary objective of these studies was to improve the elevated temperature strength of tantalum with minimum degradation of fabricability and low-temperature ductility by alloying. Several alloys were found to exhibit hot tensile strengths in the excess of 25, 15, and 10 ksi at 2700°, 3000°, and 3500°F, respectively, combined with excellent cryogenic toughness and ductility. Particularly outstanding in this respect are alloys in the system Ta-Mo-W. Ternary parameter curves describing hot-strength, low-temperature ductility, recrystallization temperature, weld ductility, and fabricability are presented for the Ta-Cb-V, Ta-Hf-W, Ta-Mo-Hf, Ta-Mo-V, Ta-Mo-W, and Ta-V-W systems. At present, only four metals qualify for large scale structural applications at temperatures above about 1800°F. These are tungsten, tantalum, molybdenum, and columbium. Research and development work on these refractory metals has progressed to the point where efforts are now primarily directed toward the improvement of high- and low-temperature mechanical properties through alloying. High melting point combined with excellent low-temperature ductility, fabricability, toughness, weldability, and high solubility and tolerance for both substitutional and interstitial solutes are important attributes of tantalum. Conversely, its high density and relative scarcity compared with other refractory metals are the major deterrents to the use of tantalum. Early studies in the Battelle alloy development program established base line data on the mechanical and metallurgical properties of high-purity tantalum.' These studies were extended to include a preliminary investigation of the effects of various alloying elements on the established base properties.2,3 Recent studies involved a more detailed investigation of promising binary alloys containing Cb, Hf, Mo, Os, Re, Ru, and W, and ternary Ta-Cb-V, Ta-Hf-W, Ta-Mo-Hf, Ta-Mo-V, Ta-Mo-W, and Ta-V-W alloys. Results of major importance obtained are given in this article. EXPERIMENTAL PROCEDURES Electron-beam-melted tantalum (Wah Chang) and high-purity alloying elements were consolidated as 150-g ingots by multiple nonconsumable arc melting under a partial atmosphere of helium. Homogeneity of the button ingots was checked radiographically. Alloy buttons measured about 1-1/2 to 1-3/4 in. in diam by about 0.35 and 0.50 in. thick. Nominal alloy compositions were checked on each alloy button by weighing after arc melting. In most instances, weight losses were within 3 pct of the total weight charged. Subsequent chemical analyses on a number of selected alloys showed interstitial contents to range as shown below: Range of Interstitial Content, ppm 0 C N H 25-75 50-100 10-50 1-5 Metallic alloying additions were found to agree well with nominal compositions based on weight change data. Fabrication directly from the cast button to sheet was conducted at low (75° to 900°F), intermediate (1800° to 2000°F), or high (3000°F) temperatures, depending upon alloy content and hardness. Evacuated stainless steel or molybdenum packs were used for fabrication at intermediate and high temperatures, respectively. The temperature required to complete recrystal-lization in one hour was determined by hardness measurements and metallographic observations (longitudinal test sections) after vacuum annealing at 180°F intervals in the range 2010° to 2910°F. All mechanical property evaluations were conducted on recrystallized sheet, nominally 0.04 in. thick. Weldability of the various alloys was screened using manual TIG welding techniques. Bend ductility (bend axis perpendicular to weld axis) was the criterion used for evaluation. Tensile specimens employed 0.200 by 1 in. gage lengths, and bend test specimens measured about 1 by 1/4 in. Low-temperature tensile tests were conducted using a crosshead speed of 0.02 in. per min up to the point of yielding, and 0.05 in. per min to fracture. High-temperature tensile tests were conducted in vacuum using a crosshead speed of 0.01 in. per min

Jan 1, 1963

By S. R. B. Cooke, H. S. Choi, I. Iwasaki

In magnetic taconite of the East Mesabi range, quartz, magnetite, and cummingtonite (OH}(Fe, Mg)(Si4O11)2) are the three major ore-forming minerals.' Fine grinding and magnetic separation of the taconite leads to a concentrate analyzing 64 to 65 pct Fe and 8 to 9 pct insoluble; the gangue content of the concentrate arising from the presence of locked magnetite-gangue particles, and of occluded gangue particles in magnetic floccules. To further upgrade such taconite concentrates, flotation appears to offer a particularly promising approach. To evaluate its effectiveness in separation, a knowledge of the flotation characteristics of each mineral comprising the concentrate becomes desirable. The floatability of magnetite and of quartz have already been reported in a previous paper,2 in which the flotation characteristics of the two minerals were correlated with the electrokinetic properties at the mineral-solution interfaces. Since cummingtonite has somewhat intermediate chemical composition between the above-named oxides, the electrokinetic and the flotation behavior of this mineral becomes of interest for both practical and fundamental reasons. In the present article the results of electrophoretic mobility measurements and of Hallimond tube flotation tests on cummingtonite are reported and are compared with those of quartz and magnetite. MATERIALS AND METHODS A sample of cummingtonite-rich taconite, received from the Mitchell pit, near Babbitt, Minn., was crushed and ground through 100 mesh, and the product was fractionated magnetically into three portions. First, a drum-type laboratory cobber was used to separate a highly magnetic portion, consisting mainly of free, but also containing locked, magnetite particles. The cobber tailing was then passed in two stages through a Franz isodynamic separator. The middle fraction was isolated, and, upon examination petrographically, was ascertained to be principally cummingtonite. The 100 to 150 mesh fraction of this sample was selected for the present study. It was cleaned by leaching briefly with hot, dilute HC1 and then by rinsing repeatedly with demineralized water. A ground and elutriated fraction of -5p cummingtonite was used for the electrophoretic measurements.

Jan 1, 1961

ONE of the fundamental reasons for the extreme rapidity with which the Porphyries developed after the trail had been blazed at Bingham was the amenability of the deposits to prospecting and proving of the ore either by churn-drilling or by diamond-drilling. At Ray churn-drill data formed the principal basis for early calculations of ore reserves; and in 1913, Inspiration floated its first bond issue for $6,000,000 on the strength of the estimate of 45,000,000 tons of sulphide ore assaying just over 3 per cent copper. The money was obtained in spite of the fact that no one ever had actually laid eyes on more than a minute fraction of that ore. The customary method of developing a copper deposit before the Porphyry era had been to sink shafts or drive adits and then to follow and expose the veins or lodes with horizontal and vertical underground workings-drifts, crosscuts, raises, and winzes. The excavated material sometimes was sampled in bulk; but always the walls of the openings would be channeled at intervals to obtain small samples representative of the ore left in place. This process was known as "blocking out" ore. It was costly and it required a great deal of time to prove the existence of immense tonnages. The early development at Utah was done in this way; likewise, at Miami. This fact helps to explain why only 3,000,000 tons of ore was reported as being developed when J. Parke Channing wrote the report on which the original Miami financing was based in March, 1908. Fortunately, his 3,000,000 tons averaged 3'per cent copper. At Ray, Seeley W. Mudd estimated 3,000,000 tons of ore in June, 1908, developed principally by underground working; but by the end of 1909, Henry Krumb was able to report 50,000,000 tons as the fruit of a little more than a year of churn-drilling.

Jan 1, 1933