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By J. C. McCarthy, J. B. Stone

AT Fresnillo a series of veins that has yielded very large quantities of silver and other metals has been developed over a length of 6500 ft. and to a depth of over 3000 ft. In the course of this work striking changes in the mineralogy and metal content of the principal veins have been disclosed and are well illustrated by assay data and ore reserve calculations. This paper describes those changes and suggests their bearing on theories of ore deposition. LOCATION The Fresnillo mines and the adjacent city of Fresnillo are in the central part of the state of Zacatecas, 35 miles northwest of the capitol city of Zacatecas, once a great silver-mining center whose total production is said to place it fourth in the world. Another famous old silver district, Sombrerete, lies northwest of Fresnillo. Fresnillo is connected by a 5-mile branch with Fresnillo station on the Mexican National Railways line from Juarez to Mexico City. Lying near the southwestern edge of the central plateau of Mexico, Fresnillo ís surrounded by a semi-arid rolling plain from which rise widely scattered low hills. One of these is Proaño hill, an inconspicuous elevation rising barely 300 ft. above the plain, but in and around Proano hill are the Fresnillo mines, and it is marked now by a great gash cut by glory-hole mining. HISTORY According to an account written in 1834 by Francisco García, then Governor of the state of Zacatecas, Fresnillo was discovered in 1554, and a presidio was established there in 1568 to protect travelers on the road between Zacatecas and Sombrerete. Little is known of the earliest mining at Fresnillo, which seemingly began soon after its discovery, but by piecing together various accounts, it appears that mines there were working in 1717 and were notably active ín 1751 under an administrator named Murguía, who left detailed notes describing them. In 1757, however, the mines became inactive because of difficulties with creditors and no doubt also because of increasing water troubles, and they remained abandoned until 1830. In 1830 the mines at Fresníllo became the property of the State of Zacatecas because the interest of Governor García had been aroused by the long disregarded notes of Murguía. Under García's energetic leadership the mines were reopened, and silver production began in 1832 ín spite of serious difficulties, including abnormal rains and an epidemic of cholera. In 1835 English capital was sought to allow installation of steam-driven Cornish pumps at the two principal shafts and to build the great hacienda de beneficio (the present Proaño hacienda). The company formed in 11835 (Cia. Zacatecano Mexicana) operated successfully until 1872, when its career was brought to an end by the political and economic disturbances

Jan 1, 1942

By A. K. Knickerbocker

Practically all underground work on the Minnesota iron ranges is done by miners working on a so-called contract wage system. This system, while it has certain advantages over the straight day's pay or company-account method of wage payment, has serious and vital defects. In view of the scarcity and demands of labor, it is important that employers of labor scrutinize their systems of wage payments carefully, not only to save losses and trouble, due to labor disturbances, but also to secure the greatest efficiency of their workmen and reduce their operating costs. It is admitted that an adequate, just, and equitable wage is the prime factor in bringing about these benefits. The wage of labor and its method of application and payment have been, and always will be, the main factors in the unrest and dissatis. faction of labor. Not only does labor want and need an adequate wage, assuming that work is adequately performed, but it wants and is entitled to a just and equitable wage. Labor must have respect for the fairness of the wage and for the fairness of the management in the application of the wage It is conceded that the Minnesota iron miners are now, and have been, in the main paid adequately, but the inherent defects of the so-called contract system prevent any just or equitable application of this wage to the various units of the labor body. The defects of the contract system, with its obvious inequalities, favoritisms, and injustices, are cancers in the brain of labor. Every thinking miner realizes these defects and knows just what they are; the unthinking do not realize the details of the subject, but each month they are forcibly reminded of these defects through the pay envelope. As practiced on the iron ranges, however, the so-called "contract " system is not a contract and the name is a misnomer. No true contractual obligation exists. As usually practised, the contract system involves the setting of a price per foot in development work, or per foot or per car, usually the latter, in slicing or stoping, by the mining captain, and assumes its acceptance, though often under protest, by the men. A price is set for each working place, in which there are usually two men per shift. This price includes labor and supplies, such as explosives, fuse and caps, shovels, carbide, etc., and the men divide the total earnings less the amount expended for supplies. The cost of the supplies charged to the men varies

Jan 1, 1920

By H. D. Hoskold

As the theory and the practice of valuing mines have never been discussed in the Transactions, a paper on the subject may be acceptable, even though not exhaustive. The method here indicated is set forth, not as a model of perfection to be followed absolutely, to the exclusion of any other system based on sound scientific, commercial and equitable principles, but merely as an aid to mining engineers and financiers in estimating the value of mining-property. This paper is intended merely to point out certain financial features of the question, and not at all to go into the theories of the formation of mineral veins, extremely valuable as it must, of course, be to understand the laws of the earth's formation and of its various changes, which are the basis of such important sciences as geology and mineralogy, and highly useful as guides in determining the probable existence and extension of mineral deposits. Financial Elements of Mine- Valuation. The practice of basing the stock-exchange price of mining shares upon reports, periodically received from the mine-captain or manager, stating that in his opinion the mine is " improving " in this or that level, and is worth so much " per fathom," is, of course, absurd. Everybody experienced in metalliferous mining is aware that a mineral vein varies in thickness and also in percentage of metal in different parts of the same mine. According to the practice just indicated, a mine must have had as many values a per fathom " as there have been given reports upon it at intervals during the year,

Jan 1, 1903

By Fred D. DeVaney

MINNESOTA taconites are extremely hard, and fine grinding is required to produce an acceptable concentrate. To reduce grinding costs, waste material is rejected by magnetic separators as soon as it is liberated. Cyclones are now used in all Minnesota taconite plants to close the grinding circuits. Erie Mining Co. installed its first grinding section at Aurora, Minn., in 1948-a 9 ½ x12-ft. mill and a fine grinding section consisting of a 10 ½ x12-ft ball mill in closed circuit with a duplex 60-in. spiral classifier. Concentrates from the magnetic cobbers treating the rod mill discharge passed directly into the classifier; the ball mill discharge was also treated in magnetic separators and the concentrate from these machines also went to the spiral classifier. Both concentrates passed through ac demagnetizing coils. It is axiomatic that for proper classification the material in suspension must be well dispersed, and it follows that magnetic concentrate must be almost completely depolarized if classification is to be successful.

Jan 8, 1957

By T. C. Mendenhall

All persons, actively engaged in your profession, must have a natural interest in the subject of weights and measures. All members of the engineering profession have to do with operations of weighing and measuring—some with measuring more than weighing, and some with weighing more than measuring—but all with both of these processes to a greater or less degree. Methods of weighing and measuring have improved constantly from the earliest times and have kept pace with the advance of other technical processes. It is, therefore, believed that you will be interested in a few remarks concerning some of the more recent advances in relation to the establishment of decimal standards of length and mass in this country. Before speaking of this, I will refer very briefly to some facts which may not be very generally known regarding our customary system of weights and measures. Although the yard is universally accepted as the unit of length, and the pound as the unit of mass, it is not generally understood, I believe, just in what respect the yard is the unit of length, or the pound the unit of mass. That is to say, it is not generally known in what degree these units have been legalized by Acts of congress. Doubtless, many of you are familiar with the facts which I will briefly recapitulate. The Constitution of the United States authorizes Congress to establish a system of weights, measures and coinage. The establishment of a system of coinage, as you know, was one of the first acts of the government, and the system then adopted is certainly one of the most perfect, if not the most perfect, that the world has yet seen. But, although Congress had the power to establish a system of weights and measures, it has never yet seen fit to exercise this power; that is to say, Congress has never yet

Jan 1, 1890

By C. C. Martin, M. C. Fuerstenau, R. B. Bhappu

Experiments revealed that quartz could not be floated in conductivity water at any pH with a long-chained sulfonate as collector. Various cations, Fe+++, Al+++, Pb++, Mn++, Mg++, Ca++, are shown to function as activators when the pH is such that the cation hydrolyzes. As the solubility product of the various cation-sulfonates was exceeded at the concentrations involved, precipitated cation-hydroxy-sulfonates, e.g. Fe (RSO3)2OH must be functioning as the collector in these systems. A number of interesting and important phenomena were revealed during a study of the response of beryl to sulfonate flotation.' Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH 3.0, about three ppm Fe+++ increased recovery of leached beryl from about 60 pct to 100 pct, whereas about four ppm Ca+ + reduced the recovery from 60 pct to 2 pct. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper Sulfonate Flotation of Beryl,' even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation-sulfonates are precipitated immediately in solution. That is, blueish-white clouds were noted to form after given additions of salts to known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe(RCO3)2OH and that bonding to the surface occurs through the hydrogen of the hy-droxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems in the presence of various cations at various values of pH. EXPERIMENTAL MATERIALS AND METHOD Sodium alkyl aryl sulfonate was chosen as the collector for the experimental work. The reagent, sup plied as a courtesy sample by the Shell Chemical Co., has the following physical properties: Physical form Solid — Finely ground Sulfonate content, pct wt 95 to 97 Molecular Weight 450 to 470 Number of carbon atoms in hydrocarbon chain 25 to 30 Melting Point, OF 250 to 260 Solubility Soluble in water with gel formation at concentrations higher than 25 pct by weight sulfonate This particular reagent was chosen because of its high active sulfonate content, long-chain length, and solid form. With the exception of the frother and sulfonate, all other chemicals were of reagent grade quality. Conductivity water was used in the experimental work. This water, made by passing distilled water through an ion exchange column, had an average measured conductivity of one micromho. Experiments were conducted at room temperature in a small glass flotation cell with the following procedure: 1) A redetermined amount of water and salt solution (e.g. CaC12 . 2H2O) were combined and the pH adjusted to a given value. 2) A given amount of sulfonate was added so that final solution volume was 130 cc. 3) One drop of Dow 250 frother was added. 4) Five g of quartz were added and the system conditioned for five minutes. 5) The pH of the system was measured (termed flotation pH).

Jan 1, 1963

By L. H. Duschak

Electrolytic zinc produced from sulfate solution and with pure lead anodes is always contaminated with a small and varying percentage of lead. The purpose of this investigation is to determine the characteristics of several lead alloys and their influence on the products of electrolysis and power consumption. The study of alloyed anodes has been a matter of interest for some years. Tainton, Taylor and Ehrlinger prepared a highly interesting paper' on this subject a year ago, in which the effects of silver-lead and some ternary alloys of lead-silver-tin were described, and the presentation of any paper on insoluble anodes will owe much to the inspirational results achieved by Dr. Colin G. Fink and Li Chi Pan in their work on insoluble anodes for the electrolysis of brine,2 and to other published papers by Dr. Fink and his coworkers embracing the development of the copper-silicon-manganese anode for the production of electrolytic copper and the general subject of anode development. The present paper describes a study of various combinations of 10 metals. The general plan of the work provides for the fabrication of the alloyed anode, its adequate conditioning by preparatory electrolytic operation, the production of cathode zinc and its analysis, the determination of the anode polarization, and other features. A list of the anodes tested, showing composition and polarization at various current densities together with the lead assay of the cathode zinc, is shown in Table 1. Determination of Anode Polarization In the determination of anode polarization under operating conditions it is essential that the anode area used be restricted to the side facing the cathode, in order that these measurements may be referred to a definite current per unit of area. It becomes necessary, therefore, to insulate the inactive face of the anode, to prevent the leakage of lines of force

Jan 1, 1930

By Philip L. Collyer

A technique for evaluating the similarity of ore deposits is presented. A Q-mode cluster analysis is performed using information on tungsten mines in North America. This is a method of grouping several samples according to their similarity based on a simple matching coefficient. Tungsten mines are grouped or clustered on the basis of geologic variables. It is possible to interpret and evaluate different ore environments according to age, mineralogy, and other variables. It is well known that variable geologic conditions influence the occurrence of certain types of minerals. If one variable is responsible and identified, that variable can be searched for in exploration. If several interrelated variables are responsible for forming a favorable environment, then recognition and identification may be more difficult or completely masked. Therefore it is helpful in exporation to isolate and identify multiple interrelated variables which control the localization of mineral deposits. Cluster analysis is useful in mineral exploration where considerable amounts of data are available for analysis. Subtle relationships that might be overlooked because the data are voluminous can be isolated using this technique. Cluster analysis can be used to establish exploration prioriy in unknown areas on the basis of similarities to known metallogenetic provinces.

Jan 1, 1976

By Ulick Evans

I SHOULD like to commence by saying how much I appreciate the honor which the American Institute of Mining and Metallurgical Engineers has done me in inviting me to visit your country, and to deliver this lecture before you. In choosing a subject, and in deciding what to include and what to omit, I have endeavored to discuss as far as possible work carried out recently in Europe with which you may not be unduly familiar. It would be poor return for your hospitality, and a mistaken sort of compliment indeed, if I were to load the lecture with accounts of researches 'carried out in your own country-researches with which you are probably better acquainted than I. Not that I have in any way excluded work done on, this side of the Atlantic from my survey; one would indeed find it difficult to write on this, or on any other branch of science, without mentioning American work. But I have endeavored as far as possible to concentrate on aspects of the case which will, I hope, be comparatively fresh to you, and I feel fairly certain that this will be in accordance with your own wishes. If a strip of iron is heated strongly at one end, the other end remaining cold, there is produced over the heated portion a layer of oxide scale, the thickness of which diminishes steadily with the distance from the hot end. Somewhere in the middle of the strip, the thickness of the oxidized layer will become comparable .to the wave length of light, and over this region the thin films give rise to a series of beautiful interference tints, commonly known as "temper colors." The colors are caused by the fact that two trains of light waves are reflected respectively from the outer and inner surfaces of the oxide film, .and the possibility arises that the "crests" of one series of waves may coincide with the "troughs" of the other, thus diminishing the intensity of the light of some particular wave length. The state of affairs in this part of the strip is shown diagrammatically in Fig. 1, in which the film thickness is enormously exaggerated, of course, in comparison with the length of the strip; the

Jan 1, 1929

By Harrison Schmitt

IN the practice of ore finding the geologist is continually confronted with the question of oreshoot extension, so that the general problem seems worthy of systematic investigation. This problem appears when the reserves are estimated and when the advisability of deepening the shaft comes up. Moreover, there is need for lower development cost to keep pace with cost reductions in other departments, or even to offset a rising cost of ore finding or ore following. This can be gained by close geologic control of the development; and much of the geology involved is that bearing on the downward, upward, and horizontal extensions of shoots. Furthermore, the purchase of a mine or prospect often depends directly on the question of shoot extension; because it is seldom that the ore is fully developed and the purchase price is almost invariably based largely on "possible" and geologically prospective ore. Most current methods for estimating "possible" and the more nebulous classes of ore are crude and indecisive. In the following pages the extension of oreshoots is the major theme, although the more basic subject, the general art of ore finding, is given some space.

Jan 1, 1929

By Arvid Holst Mortensen

The rational exploitation of deposits for cement manufacture requires evaluation of the material, the planning of the quarrying and the right choice of quarry machinery. By using a computer for all evaluations and planning work the optimal recovery of material is arrived at and a quarry layout - and machinery is decided upon. The result will be uniform production throughout the lift of the deposits using a rationally chosen quarry equipment.

Jan 1, 1977

By E. E. Brownson

THIS paper will be confined to the treatment of methods as applied in the laboratory of the Boston and Montana Reduction Department of the Anaconda Copper Mining Co. at Great Falls, Mont. As the electrolytic plant of this company operates at a current density of approximately 35 to 40 amperes per square foot when running up to capacity, the arsenic and antimony content of the anodes delivered to the, plant is of considerable importance as bearing on the purity of the refined cathodes turned out. Owing to the rather high relative percentage of antimony, it has always been the custom to determine antimony as well as arsenic in all forms of copper. Thus, anodes have been analyzed in which the antimony was about equal to the arsenic although the average shows about 2 parts of arsenic to 1 of antimony. In the refined copper the relative proportions of the two impurities vary considerably, but probably in the average are about equal. In this latter case, the percentage of the two is so small that ordinarily no attempt is made to separate them, the report of analysis showing percentage of As and Sb combined. Although rapid and exceedingly accurate determinations of arsenic may be made by means of various distillation schemes, the determination of antimony, either by itself or together with arsenic, has always been more or less cumbersome and has required a considerable amount of time. By the methods, details of which follow, the determination of arsenic and antimony, either separated as in the case of anodes or together in case of refined copper, is accomplished in 24 hr. from the time the sample is received by the chemist.

Jan 8, 1913

By Alphonse Hennin

It is well known that under certain conditions ammonia is found in the gas produced by the distillation of coal. Until recently it was held, and many still believe, that this ammonia exists in the coal, and is a natural product of the destructive distillation, varying in percentage, like the other products, according to the nature of the coal, but not formed synthetically beyond that limit. This opinion is in contradiction with well-established facts concerning the formation of ammonia from the elements of the coal. If any ammonia exists as such in the coal, the quantity is insignificant. The purpose of this paper is to explain the theory of the formation of ammonia during distillation, and call the attention of the members of the Institute to its application in connection with the production of heating-gas for metallurgical purposes, etc. For many years little or no importance was attached to the presence of ammonia in coal-gas. It was deemed by the gas-manufacturers an undesirable product of the process, as one of the impurities to be removed; and no attempt was made for its recovery. Not until its practical extraction and utilization was found possible, did scientists commence to investigate the question. Little was known about the nitrogen of the coal, and still less about the reactions leading to its transformation into ammonia. A. W. Hofmann, I believe, was the first to establish a relation between the percentage of nitrogen in the coal and the proportion of ammonia in the coal-gas. As early as 1863 he pointed out that, in dry distillation, such as is practiced in the manufacture of illuminating-gas, only one-third of the total nitrogen in the coal is liberated, two-thirds remaining in the coke. It is no longer possible to doubt that the ammonia is a synthetical product, resulting, under certain conditions, from the combination of the,elements of the coal. Chemistry teaches that ammonia is formed in many cases when

Jan 1, 1893

By R. S. Archibald

THE Blueberry mine is about 10 miles west of Ishpeming, Marquette County, Michigan. The property consists of about 2000 acres in sets. 3, 4 and 5, T. 47, N.R. 28W. and sets. 32, 33 and 34, T. 48, N.R. 28W., and, excepting one intervening 80-acre tract, contains the iron formation for a length of about 2 1/4 miles. The property is traversed by State Highway M-28 and is served by three railways, the Chicago & Northwestern, the Duluth, South Shore & Atlantic, and the Lake Superior & Ishpeming. The Northwestern transports the ore to a dock at Escanaba; the other railways, to Mar¬quette. Ore for Chicago goes via Escanaba and that for Lower Lake ports, as Detroit, Cleveland, and Buffalo, via Marquette.

Jan 1, 1935

By W. E. Forsythe

Different forms of optical pyrometers are discussed and the advantages and disadvantages of the different types for measuring high temperatures are pointed out. These advantages and disadvantages lead to the selection of the disappearing-filament type of optical pyrometer for most work. Attention is directed to the necessity for the use of a monochromatic screen with a pyrometer, which leads to a discussion of the meaning and use of the effective wave length of the screen. Methods of calibrating the optical pyrometer are outlined and it is shown that an optical pyrometer can be calibrated just as definitely as any other temperature-measuring device. Accuracy tests are included, in which it is shown that excellent results can be obtained by even untrained or slightly trained observers with this form of optical pyrometer. The various corrections that are necessary in this kind of work are indicated, including corrections for stray light, for absorption of windows, of smoke, and so forth. The troublesome problem of measuring the temperature of bodies that do not radiate like a black body is discussed and the corrections for reducing such readings to the true temperature are given for a number of different materials. Introduction The fundamental idea of temperature depends upon our temperature sense and bodies are said to be hot or cold depending upon the reaction of our hands or some other part of the body to the heat from the source investigated. For measuring the temperature some instrument must be devised, since the temperature of the source studied is apt to be so hot as to greatly injure any part of the body that comes near it, to say nothing about direct contact with it. Definition of Temperature.—The temperature scale is based upon two fixed points, the temperature of freezing water and the temperature of boiling water. This temperature interval, depending upon the scale

Jan 1, 1936

By W. E. Forsythe

Different forms of optical pyrometers are discussed and the advantages and disadvantages of the different types for measuring high temperatures are pointed out. These advantages and disadvantages lead to the selection of the disappearing-filament type of optical pyrometer for most work. Attention is directed to the necessity for the use of a monochromatic screen with a pyrometer, which leads to a discussion of the meaning and use of the effective wave length of the screen. Methods of calibrating the optical pyrometer are outlined and it is shown that an optical pyrometer can be calibrated just as definitely as any other temperature-measuring device. Accuracy tests are included, in which it is shown that excellent results can be obtained by even untrained or slightly trained observers with this form of optical pyrometer. The various corrections that are necessary in this kind of work are indicated, including corrections for stray light, for absorption of windows, of smoke, and so forth. The troublesome problem of measuring the temperature of bodies that do not radiate like a black body is discussed and the corrections for reducing such readings to the true temperature are given for a number of different materials. Introduction The fundamental idea of temperature depends upon our temperature sense and bodies are said to be hot or cold depending upon the reaction of our hands or some other part of the body to the heat from the source investigated. For measuring the temperature some instrument must be devised, since the temperature of the source studied is apt to be so hot as to greatly injure any part of the body that comes near it, to say nothing about direct contact with it. Definition of Temperature.—The temperature scale is based upon two fixed points, the temperature of freezing water and the temperature of boiling water. This temperature interval, depending upon the scale

Jan 1, 1936

By R. H. Lee

WITHOUT doubt, one of the most frequent and serious annoyances connected with the practical running of a blast-furnace, especially in single-furnace plants, is caused by low steam, in spite of the fact that all boilers at blast-furnaces have grates for burning coal, and that coal is more or less continuously burned upon them, from three to a dozen men being pretty constantly engaged around the boilers as firemen or coal- and ash-handlers. At times, when the furnace is ? tight," all available men are put on to assist the regular firemen; yet sufficient steam cannot be got to keep the engines up to their regular number of revolutions, while the stoves, deprived of the gas which has been sent to the boilers, run cold, so that, when the furnace loosens-up and resumes the regular rate of driving, the blast is very considerably below normal temperature, and a.' cold," or at best a " high-sulphur," east is the result. Again, it often happens that a furnace, running at its best, becomes temporarily a little too hot; the pressure rises; the amount of gas made' is diminished; the steam soon commences to go down; and a small scaffold is likely to form before the furnace has been brought back to the proper rate of driving, and thus enabled to take its regular amount of blast. The usual remedy is either to "jerk" the furnace by a sudden, brief intermission in blowing, or to cool the furnace by lowering the heat of the blast; but if the lower blast-temperature be maintained too long, the hearth and descending stock may be cooled below the " critical temperature " mentioned by Mr. .Johnson, and the furnace may go to the other extreme, and become cold. This is especially the case when coal or coke, high in sulphur, is used:

Jul 1, 1906

By C. H. Hewitt, J. T. Morgan

The Fry cocurrent in situ combustion project was carried out in a 3.3-acre portion of a lenticular body of Robinson sandstone of Lower Pennsylvanian age. This particular sand body is about 12,000 ft long and 3,500 ft wide; it varies in thickness from 0 to 55 ft, trends northeast-southwest, and occurs at depths between 880 and 936 ft. The reservoir is made lip of three distinct types of sandstone, each having characteristic reservoir properties. (See Table I.) Textural gradients, sedimentary structures, erosional basal contact, absence of marine fossils, and geometry of the sand body all indicate that the sandstone is of fluvial origin and part of an extensive complex of river-deposited sedirnents. Geographically oriented cores reveal that the direction of depositing currents was to the southwest, parallel with the sand-body trend. Directions of maximum pernleability also parallel the northeast-southwest trend. The layered nature of the sandstone reservoir and its directional properties have controlled the areal distribution of produced gas, the ignition behavior, and the vertical profile and horizontal extent of the conbustion zone. INTRODUCTION This paper is the first of a series of three papers that describe Marathon Oil Co.'s Fry in situ combustion test. This first paper contains the results of a detailed study of the geology and reservoir characteristics of the Robinson sandstone reservoir in which the Fry test was conducted. The second and third parts of this series report on the field operations' and performance. The geologic work reiated to cores cut through the combustion zone, and to the effect of reservoir properties on the combustion process is included in the third paper.' GEOLOGIC STUDY OF THE FRY RESERVOIR The close spacing of continuous cores in the Fry combustion site provided an unusual opportunity to study the details of distribution of lithology and reservoir properties within a petroleum reservoir. The objectives of the study were: 1. To determine the distribution of rock types within the Robinson sandstone in the Fry area; 2. To determine the relationship of porosity and permeability to rock properties and establish the distribution and homogeneity of reservoir properties; 3. To determine the origin of the Robinson reservoirs so that attempts could be made to predict the size, shape, distribution, extent and continuity of Robinson reservoirs; and 4. To determine what effects, if any, the reservoir rocks might have on the combustion process, so that the process might be better evaluated. AVAILABLE MATERIALS Continuous cores were cut from 14 wells in the vicinity of the Fry site. Ten of the cores are from within the 3.3-acre pattern; six of the 10 were cut prior to combustion, and four were cut through the combustion zone. Cores from the Emma Fry No. 15, Wampler 0-2 and Fry B wells (Figs. 1, 2 and 9) were geographically oriented by the Eastman Oil Well Survey Co. Maps, electric

Jan 1, 1966

By T. Sterry Hunt

This remarkable mine, to which attention has lately been drawn, is situated not far from the New River, in Ashe County, North Carolina, on a spur of the Blue Ridge which lies between the main crest of this name and the so-called Iron Mountain, a part of the Unaka or Smoky Mountain range. It is on a true fissure-lode, which cuts the strata of gneiss and mica-schist of the region. These, which have the lithological characters of what I have called the Montalban or White Mountain series, have here a dip of about forty-five degrees to the southeast, while the lode is vertical, with a course north 60' east. Both the country-rock and the lode, as is usual in this region, are decomposed to considerable depths; and the latter exhibits a cap of hydrous peroxide of iron or gossan, blocks of which, left by the denudation of the softer inclosing rock, are scattered over the surface, and first called attention to the locality as a source of iron ore. In sinking upon this lode, it was found that the porous gossan at a certain depth became charged with carbonate and red oxide of copper, and lower down was replaced by sulphuretted ores of this metal of remarkable richness. This deposit was worked for copper, in an irregular manner, before the late civil war, but was afterwards abandoned, and only reopened during the present year, by Messrs. S. S. & J. E. Clayton, of Baltimore. The outcrop has been traced for 1900 feet, and the sulphuretted copper ores have been met with in five shafts in a distance of 661 feet, a drift having moreover been carried for the above distance through the solid ore. The breadth of the lode, so far as opened, varies from six to eight feet to fourteen feet in places, and that of the outcrop of gossan is, in some parts, twenty feet. After comparing this deposit with the copper mines of Ducktown, Polk County, Tennessee, and those of Carroll County, Virginia, it is evident that we have, at Ore Knob, to do with the same kind of black ores as were met with in these mines, and will be noticed further on, Beneath the gossan, at Ore Knob, is found, in some parts, an iron-black, friable, drusy, crystalline, sulphuretted ore, inclosing grains of quartz, garnet, and magnetite, besides a black non-magnetic mineral, not attacked by nitric acid. This ore contains about 36 per cent. of copper, and portions have the mineralogical charac-

By Earl Hunner

IT is common knowledge that the iron orebodies of the Mesabi range lie nearly horizontal and are of trough or blanket-like types. These orebodies are from a few feet to several hundred feet thick and vary from a few acres in extent to the size of the largest one, at Hibbing, Minn., which is over 1 mile wide and 3 miles long. They are covered with sand, boulder and clay overburden and occasionally, shallow depths of ledge material, varying in total depth from about 20 to 200 ft. Large areas are not capped with overlying ledge material; the top of the ore lies directly underneath the surface material. Because of the comparatively great tonnage of ore, open-pit mining has made tremendous strides since the first open-pit ore was shipped from this range by the Merritt brothers, from the Mountain iron mine in October, 1892, and along with the great development of open-pit mining on the Mesabi range has gone a tremendous change in the character of equipment used.

Jan 1, 1930