Search Documents

By K. E. Nelson

The effect of thorium and zinc variations on the strength and 100-hr creep characteristics of Mg-Th-Zn-Zr alloys was investigated. Optimum resistance to creep at 650° and 700°F are attainable within a certain range of thorium and zinc contents. This range does not conform to that which develops maximum tensile properties. RAPID advances have been made during the last few years in the development of magnesium alloys for elevated temperature applications demanding high resistance to creep. The beneficial effect of rare-earth metals on the creep resistance of magnesium alloys has been emphasized by a number of publications1-13 and such alloys are now in commercial production. The use of thorium as an alloying ingredient in magnesium was mentioned by McDonald and also in two Alien Property Custodian patent applications.10,17 The initial observation of Sauerwald that thorium contributes still higher creep resistance to magnesium than is attainable with rare-earth metals has recently been substantiated.'" " In fact, it has been demonstrated that the useful temperature range of magnesium alloys is appreciably extended by the use of thorium. In all cases, it was observed that zirconium must be included in the alloys in order to render them fine grained and more readily castable. Several recent publications:2-27 indicate that a still further improvement in creep resistance and a further extension of the useful temperature range can be realized by the addition of zinc to alloys. The primary purpose of this paper is to present the results of a comprehensive study of the effect of zinc on the strength and creep characteristics of Mg-Th-Zr alloys. Compositions covering the range of thorium content from M to 6 pct and zinc content from 0 to 5 pct have been investigated. The creep characteristics at 650" and 700°F reported in this paper are based on results of tests of 100-hr duration. It is appreciated that creep tests of 100-hr duration might not yield adequate data for design purposes for parts with much longer expected life. However, for the purposes of the present discussion, it is felt that the combination of stresses and temperatures used in the 100-hr creep tests have yielded a clear representation of the compositional variation of creep resistance at the temperatures investigated. Creep tests of 1000-hr duration are now in progress on a few of the most promising alloys. Preparation and Testing of Alloys The alloys studied in this intensive investigation were prepared in 25 lb capacity mild steel crucibles. The thorium, zinc, and zirconium were alloyed and poured as described in earlier publications The thorium was introduced into the melt in the form of a Mg-Th hardener," the zinc added in the metallic form, and the zirconium alloyed in the form of the commercial hardener containing magnesium and 30 to 50 pct Zr.10, 26 Fluxing practices for melting and refining were the same as for magnesium-rare-earth metal-zirconium alloys. The melts were sampled for analytical determinations and poured into separately cast 1/2 in. diameter standard tensile bars. The test bars were given a precipitation treatment of 16 hr at 600°F in laboratory furnaces. It has been shown by other tests that a high temperature solution treatment followed by an aging treatment is unnecessary for the development of optimum properties in Mg-Th-Zn-Zr alloys. The selection of 600°F as the aging temperature was based on an attempt to achieve metallurgical stability without coalescence of the undissolved phases and the attendant loss in strength. The thorium, zinc, and zirconium contents of each melt were determined chemically. The zirconium contents are reported in two parts, "soluble" and "insoluble," referring, respectively, to the portions present in the alloy which are soluble and insoluble in dilute HCl acid. Distinction is being made between these two components of the zirconium content in the alloys because it has been found that only that portion of the zirconium content which is soluble in dilute inorganic acids affects the structure and properties of the alloys. The usual impurities consisting of copper, iron, manganese, and nickel were determined spectroscopically. The analysis for each melt is listed in Table I. A description of the methods of tension and creep testing has been detailed in earlier papers. The tests were performed with the cast skin re-

Jan 1, 1954

By Henry Mulryan

THE largest and purest known deposit of diatomite is being actively mined and processed 3 ½ miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Manville Products Corporation. The workings FIG. 1.-LOCATION OF DIATOMITE DEPOSIT AT LOMPOC. cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoc, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1936

By Henry M. Howe

THIS paper gives the composition of the iron and slag at different stages in the "air-furnace" process of preparing "hard metal," or white cast-iron, for conversion into malleable cast-iron by annealing. The details of the process are given in an appendix. One of us had been trying for years to work some chemist of some of our malleable-iron works up to a degree of enthusiasm which would lead him to make such au investigation. It would have had the advantage of the greater familiarity with the conditions which one habitually on the spot must have. Failing in this, he made use of an opportunity which presented itself of taking samples here represented, with such fairness as the conditions permitted, holding firmly that a rough approximation to the truth is better than the complete lack of data, or that a bird in the hand is worth two in the bush. We hope that this attempt may stimulate others effectively to duplicate this work, and thus correct or confirm it. Our results are shown in Table I. and graphically in Figs. 1 and 2. Discussion.-At the time when the first two samples were taken, the metal and slag were still too sluggish to permit fair sampling, and not until sample 6 were the conditions really favorable, because at the time of the fourth sample the metal was not fully melted, and even at the time of sample 5 it was still sluggish. Indeed, the slag was probably very heterogeneous throughout, because it took up silica and alumina rapidly from the bottom, and because it was so siliceous as to be sluggish at this relatively low temperature. This hetero-geneousness is exaggerated in the two samples of slag 8, apparently by the great viscosity due to its extraordinary acidity. Note that the manganous oxide of one sample is about two and

Mar 1, 1909

F. E. BASH, Philadelphia, Pa.-In order to make a definite check on the emissivity of crucible steel under works conditions, a test was planned and executed by the plant of the Midvale Steel Co., by a Sub-committee, as follows: Five crucibles were put in a crucible furnace with-the normal charge and were treated in the same manner as a number of others that were charged at the same time; the only difference was that the five cur-cibles had lids with.2-in. holes in the center. It was thought that after the crucibles were removed from the furnace a reading could be made through the hole in the lid with the optical pyrometer and that such a reading would give the true temperature of the steel as black-body con-ditions should prevail inside the crucible. If after obtaining the true temperature, the crucible lid were removed and the steel poured into the ladle, the apparent temperature could be taken by sighting on the steel stream and the emissivity obtained from the two temperature values. Such a test was carried out with five crucibles. About a third of the crucibles charged into the furnace with the five experimental ones were first drawn from the furnace and poured into the ladle. The experimental crucibles were then drawn and readings of the true temperature were made

Jan 12, 1919

1938 ABERNATHY, G E Feb 6, 1948 Min & Met Apr 1948 1937 ADAMS, ARMY Aug 20, 1949 Min Eng Dec 1949 1946 ADDY, GEORGE E Sept 24, 1950 Min Eng July 1951 1920 ALDERSON, WILTON P Feb 1951 Min Eng Sept 1952 1896 ALDRICH, T H , JR May 24, 1950 Min Eng Aug 1950 1942 ALDRIDGE, LEONARD June 8, 1952Jrn Met Sept 1952 1919 ALLEN, ROLLAND C July 18, 1948 Min &Met Sept 1948 1950 ANDERSON, C P Unknown Min Eng Feb 1951 1937 ANDERSON, JOHN H May 10, 1950 Min Eng Aug 1950 1914 ANDERSON, L DOUGLASS Unknown Min Eng Nov 1951 1948 ANDRAU, E W K Oct 20, 1951 1936 ANDREWS, CHARLES B Apr 19, 1950 Min Eng June 1950 1918 ARMITAGE, PAUL June 28, 1949 Min Eng Oct 1949 1924 ARMSTRONG, PERCY A E Jan 23, 1949 Min Eng May 1949 1906 ARNOLD, CHARLES LE NEVE Aug 7, 1949 Min Eng Oct 1949 1945 ARNOLD, HAROLD S Aug 7, 1950 Min Eng Oct 1950 1936 ASH, JAMES E Dec 17. 1949 Min Eng Apr 1950

Jan 1, 1952

By ERNEST A. HERSAY

ACCURATE ore-sizing with screens is drawing attention to certain details that now, more than ever before, require attention. There are many tests that must be preceded by careful sizing. The assayer often could profit by a more careful selection of screens. In milling, more attention is given the slimes produced. Cement-manufacturers are pulverizing and screening finer than they formerly did, and others are reducing materials to fine sizes at high cost, with screens used to govern the fine¬ness of the pulverized product. Fine screens are expensive, easily injured by mis-use, are carried in stock sparingly by most dealers, and are handled often by those who know little about them except their designated number. More attention, on the whole, needs be given the actual size of the mesh-openings, and less emphasis placed upon any custom or conventionality in numbering. An effort to classify wire screens, in this respect, leads at once into computations, where one is confronted with details of sizes and standards, of different wires, different gauges, and different customs. There is always uncertainty about the exact working-size of a screen until one gives the matter special attention, and devotes more time to it than its simplicity seems to demand. To know only the number is not sufficient for all uses. Often, in sets, superfluous sizes are used; and sizes are omitted that are of critical importance. In wire screens, the use of different standard sizes of wire makes important differences in dimensions that must be taken into account. The dealer usually grades screens by the number of openings per linear dimensions, regardless of the size of the openings or of the wire. Certain 100-mesh screens in use are found, by measurement, to he actually coarser than others of 90-mesh, a result which is due, of course, to the use of larger

May 1, 1906

By William Wraith

At the Washoe smelter, Anaconda, Mont., the blister-copper from the converters is transferred, by means of a crane, to a re-fining-furnace, in which it is brought to proper pitch by means of air and poles. From this furnace the refined copper, containing gold and silver, is poured into cast-iron molds placed on a platform-convejor, giving an anode 36.75 in. long, 35 in. wide, and 2 1/16 in. thick. By reason of a disagreement between the smelter and the refinery, in reference to the silver-content of the anodes, it becanle necessary to investigate the methods of sampling used. 11. SMelter Method of SampliNg. At the smelter the sampling is done by " shotting " into water a small portion of the molten stream of copper as it flows from the furnace, by " batting " the stream'with a wooden paddle. The first sample is taken 30 min. after the pouring i.: started, three other samples being taken at 1-hr. interrals, each sample Weighing from 4 to 6 oz. The samples are dried, esamined for particles of burnt wood, screened on a 10-mesh screen of NO. 8 wire to remove the fines, the oversize then screened on a 4-mesh screen of No. 20 wire to remore the coarse, the undersize of this screen being taken as the sample. The four portions thus obtained are thoroughly mixed and split in half by passing over a 16-slot splitting-device, slots being 0.5 in. wide. One-half of the sample is sent to the laboratory for analysis and one-half kept as a duplicate. 111. Refinery Method of Sampling. The method used at the refinery and also used in this in1-estiyation is the one developed by Dr. Edmarcl Keller, of

Jan 1, 1911

By John C. Osmond

One of the least known geologic regions in the U.S. is the area now called the Basin and Range Province. It is paradoxical that so little geologic information has been compiled for a province that has yielded billions of dollars worth of metals and is currently producing a small amount of oil. Regional stratigraphic studies of parts of this large territory have been published only recently, and regional structural interpretations of even parts of the province are rare in the literature. This, of course, does great injustice to the earliest workers: Gilbert, Russell, Le Conte, Spur, Louderback, and others, who recognized the area as distinctively different from the rest of North America. Their simplified picture of the structure of the ranges and the province as a whole is the groundwork for present understanding and has never been superseded. Since their early works, however, geologic data from the province has consisted largely of detailed reports of widely scattered mining districts. Each district has been described as though it were an island in an unknown sea.

Jan 3, 1960

By R. W. Snyder, W. H. Guilinger, B. S. Gottfried

Two numerical methods are presented JOT solving the equations Jor one-dimensional, multiphase /low in porous media. The case oF variable physical properties is included in the Formulation, although gravity and capillarity are ignored. Both methods are analyzed mathematically, resulting in upper and lower bounds for the ratio of time step to mesh spacing. The methods are applied to two- and three-phase waterflooding problems in laboratory-size cores, and resulting saturation and pressure distributions and production histories are presented graphically. Results oJ the tuo-phase flow problem are in agreement with the predictions of the Buckley-Leuerett theory. Several three-phase flow problems are presented which consider variations in the water injection rate and changes in the initial oil-and ujater-saturation distributions. The results are different physically from the two- phase case; however, it is shown that the Buckley-Lez~erett theory can accurately predict fluid interlace velocities and displacing-fluid frontal snturations for three-phase flow, providing the correct assumptions are made. The above solutions are used as a basis JOT et~aluuting the numerical methods with respect to machine time requirements and allowable time step for a fixed mesh spacing. INTRODUCTION Considerable progress has been made in recent years in obtaining numerical solutions of the equations for two-phase flow in porous media. Douglas, Blair and Wagner2and McEwenll present different methods for solving the one-dimensional case for incompressible fluids with capillarity (the former using finite differences, the latter with an approach based upon characteristics). Fayers and Sheldon4 and Hovanesian and Fayers8 have extended these studies to include the effects of gravity. West, Garvin and Sheldon, l4 in a pioneer paper, treat linear and radial systems with both capillarity and gravity and they also include the effects of compressibility. Douglas, Peaceman and Rachford3 consider two-dimensional, two-phase, in compressible flow with gravity and capillarity and Blair and Peaceman1 have extended this method to allow for compressible fluids. No one, however, has examined the case of three-phase flow, even for the relatively simple case of one-dimensional flow of incompressible fluids in the absence of gravity and capillarity. In obtaining a numerical technique for simulating forward in situ combustion laboratory experiments, Gottfried5 has developed a method for solving the one-dimensional, compressible flow equations with any number of flowing phases. Gravity and capillarity are not included in the formulation. The method has been used successfully, however, for two- and three-phase problems in a variable-temperature field with sources and sinks. This paper examines the algorithm of Gottfried more critically. Two numerical methods are presented for solving the one-dimensional, multi-phase flow equations with variable physical properties. Both methods are analyzed mathematically, and are used to simulate two- and three-phase waterflooding problems. The numerical solutions are then taken as a basis for comparing the utility of the methods.

Jan 1, 1967

INTRODUCTION TO PROBABILITY THEORY The mathematical theory of probability provides the foundation for the interpretations and inferences that can be made from statistical techniques. Probability theory is a broad field of study in itself, and can only be touched on here in order to provide the necessary back- ground for a more complete understanding of statistical analysis. Probability is concerned with the outcome of random events. It had its beginnings in the theory of games of chance which were of great interest to European mathematicians during the last half of the 17th century. The outcome of a random process or experiment is defined as an event. The collection of all mathematical points associated with each event is called the sample space for an experiment. Consider a random experiment having a finite number, n, of possible outcomes, some of which have a characteristic A. What is the probability that A will result from a single

Jan 1, 1980

By Clarence Zener

IT is customary to regard the stress-strain relation as consisting of two parts, the elastic region and the plastic region. The essential attribute of the plastic region is the presence of a permanent set, which remains upon removal of all stresses. The essential attribute of the elastic region is the absence of such a permanent set. Absence of a permanent set does not imply a linear relation between stress and strain, nor even a single valued relation. In fact, in no real metal is stress a single valued function of strain in the elastic region. The property of a solid in virtue of which stress and strain are not uniquely related in the elastic range will be called "anelasticity." The purpose of the present article is to review and correlate the past work upon the anelasticity of metals. The following paper by W. A. West124 describes investigations upon anelastic properties of iron. Many manifestations of anelasticity have been observed, the first as early as 1835 by Weber.1,2 In his experiments Weber subjected a specimen to a constant load (or deformation) for a given time, and then suddenly removed the load. He observed that most of the deformation suddenly disappeared, but that there remained a residual deformation, which disappeared only gradually with time, as is illustrated in Fig. I. The occurrence of a residual deformation which only gradually disappeared, Weber called the elastic after-effect (Elastische Nackwirkung). An extensive review of the early work upon elastic after-effects has been given by Auerbach.3 Another manifestation of anelasticity is the dependence of the elastic constants-e.g., Young's modulus upon the method of measurement. Thus, if dynamic methods are used, the measured value will depend upon the frequency of oscillation. Still another manifestation is dissipation of energy attending vibration, called damping or internal friction. One objective of metallurgical science is the understanding of the plastic and fracture properties of metals in terms of their microstructure. Through such an understanding will come the ability to design microstructure to give the desired mechanical properties. A study of an elasticity will furnish an invaluable aid in the attainment of this objective. Such studies, when properly guided, yield information regarding the relation between stress and strain in the individual components of the microstructure. In order, however, that this type of information may be obtained, it is necessary that the experimental studies of anelasticity be interpreted by the appropriate mathematical analysis. This article, therefore, starts with the mathematical formulation of anelasticity.

Jan 1, 1946

By C. H. Lieb

ONE astounding fact in the production of petroleum is the comparatively recent realization by producers that flowing production is the cheapest crude produced. About 1910 or even later, operators actually endeavored to get a producing well to pumping as quickly as possible after completion. A well was not really considered to be completed until it was operating on the pump. Remarkable progress has been made since then. It was not until about 1920 that producers began to take a serious interest in pressures and to think a little about proper methods of handling oil wells. Pressure gauges were installed, and records of pressures maintained, which was quite an innovation. Desultory experiments were made with tubing of different sizes, as well as experiments with placing the bottom of the tubing string at different levels in the well. Probably the first important departure from customary procedure was about 1926, during the Seminole development, when gas lift

Jan 1, 1936

By E. M. Chance

HERBERT M. WILSON, Pittsburgh, Pa. (written discussion).-Permit me to endorse the author's conclusions and their form of presentation as ,being, in my judgment, the last word 'on the subject of lights for the illumination of coal mines. I also feel that the open-flame oil lamp has outlived its usefulness, and that it should go, in the interests not only of safety but of efficiency. Where an open-flame lamp can be used with safety in non-gaseous mines, the acetylene light adds materially to efficiency by its better illumination, and to safety for the numerous reasons given by Mr. Chance. The latter, however, lays chief stress on the value of the acetylene because of its non-fouling and non-obscuring effect on the atmosphere. Another important advantage over any other form of illumination is the clear, bright light projected at the point where the workman may look for danger. The better illumination materially safeguards the worker against obstacles over which he may stumble when traveling, and against dangers from falls of roof or of coal, weakness in timbering, and similar conditions. The acetylene lamp, where it may be used with safety, has advantages even over the present electric cap lamp, in that it gives a higher luminosity; and when the miner comes to learn its signals, as he will in time, just as he learns those given by the open-flame or the safety lamp, he will find that the acetylene lamp is a fair detector not only of methane but of carbon dioxide, as clearly shown by Mr. Chance. The only, serious objection, raised against the use of carbide lamps. has been recently in Pennsylvania, due to the belief of the State Mine Inspection Department that it endangered miners working on pillar work, or other places where carbon dioxide might accumulate, or where there is lack of sufficient ventilation, and because it was believed that the indications of the carbide lamp would not give the miner sufficient warning. On this point Mr. Chance has clearly shown the fallacies of the objections. I may add that for those unable to detect carbon dioxide with the acetylene lamp, the maximum of protection would be afforded by using an open oil lamp or a flame safety lamp in such places; or, because the miner might not watch his oil light, a better, protection still would be offered by a sufficient number of daily inspections of such working places by a fire boss or other official, with flame safety lamp.

Jan 4, 1917

By Earl W. Palmer, Cyril Stanley Smith

A study of the precipitation-hardening of copper steels1 led the authors to investigate malleable iron containing copper, for the low-carbon ferritic matrix in malleable iron should lend itself admirably to precipitation-hardening. It was soon found that in addition to rendering malleable iron susceptible to improvement by precipitation-hardening treatments, copper has another potentially useful effect as an accelerator of graphitization. Brief mention of these effects was given in a general paper by Lorig and one of the present authors2; the present paper gives further details on the graphitization and precipitation-hardening effects only. After the completion of this work a paper by L. Lykkin3 appeared, confirming the authors' conclusions regarding graphitization. Material Used After some preliminary heats had been made in the laboratory to determine the effect of copper, several castings from commercial air-furnace heats were obtained, and data from these alone are given here. Part of the metal was poured directly and part was treated in the ladle with the desired amount of copper before pouring. Green-sand molds were used, each holding two tensile test pieces of the form adopted by the Malleable Iron Research Institute, or two bars for graphitization studies, 5/8 in, in diameter and 9 in. long, fed through two enlarged sections equidistant from the middle and ends of the bars. Risers of suitable size insured sound castings. Tensile tests were made on the castings after commercial mallealleizing and after special heat treatments to be described. The analyses of the white irons are given in Table 1.

Jan 1, 1935

By Cyril Stanley Smith, Earl W. Palmer

A study of the precipitation-hardening of copper steels1 led the authors to investigate malleable iron containing copper, for the low-carbon ferritic matrix in malleable iron should lend itself admirably to precipitation-hardening. It was soon found that in addition to rendering malleable iron susceptible to improvement by precipitation-hardening treatments, copper has another potentially useful effect as an accelerator of graphitization. Brief mention of these effects was given in a general paper by Lorig and one of the present authors2; the present paper gives further details on the graphitization and precipitation-hardening effects only. After the completion of this work a paper by L. Lykkin3 appeared, confirming the authors' conclusions regarding graphitization. Material Used After some preliminary heats had been made in the laboratory to determine the effect of copper, several castings from commercial air-furnace heats were obtained, and data from these alone are given here. Part of the metal was poured directly and part was treated in the ladle with the desired amount of copper before pouring. Green-sand molds were used, each holding two tensile test pieces of the form adopted by the Malleable Iron Research Institute, or two bars for graphitization studies, 5/8 in, in diameter and 9 in. long, fed through two enlarged sections equidistant from the middle and ends of the bars. Risers of suitable size insured sound castings. Tensile tests were made on the castings after commercial mallealleizing and after special heat treatments to be described. The analyses of the white irons are given in Table 1.

Jan 1, 1935

CHARLES CATLETT, Staunton, Va.-A great many important things have been said in an interesting way but the most startling, to me, is that for 25 years, the price has been in the neighborhood of $1.00, with a minimum of 86 cents and a maximum of about $1.25. It is evident that during all that time the price was inadequate. The amount paid to be divided between the land owner, the capitalist, and the laborer was too limited or too irregular to permit of a healthy condition; yet it is evident that the enormous industrial development of this country was fostered by this very cheap coal, probably the cheapest that has been provided in quantity in any country. I entered the coal business when the price was lowest and my interest and sympathy went out to the man who spent his days in the dirt and foul air of a mine and I was filled with schemes for helping. But at the end of the year, after exercising every economy and in blissful ignorance of proper depreciation and obsolescence, there was still only a profit of 1 cent per long ton for what I think is one of the best coals in the world, the best grade of New River coal. We are now paying a great deal more than we did a few years ago and probably will continue to pay more for some time; but any one who thinks we will not have low prices again is very young or very forgetful. Yet we must have larger profits if the industry is to be healthy, if the three parties to the production are to get adequate returns and be in shape to provide the improvements which will be needed to take the place of and supplement the man-power. This will come when the men are making so much money that the operator wants to replace the man by a machine, and when the operator is making so much money as to be in a shape to make the improvements. He will not put in machinery unless the machinery will save money. We have got to pay a higher prime cost for coal, but engineering skill will teach us how to handle it better and use it more economically, and the ultimate result ought to be of advantage to the public.

Jan 3, 1920

By S. F. Shaw

IT IS generally recognized that the natural gas absorbed in petroleum plays the leading r6le in moving the oil through the sands to the well and supplies the energy that delivers the oil to the surface when the wells are flowing. It is the purpose of this paper to note the amount of oil that could be lifted by this gas if 100 per cent. efficiency were obtained and the efficiencies actually obtained in the use of this gas. An article in MINING AND METALLURGY,' stated that in a Wyoming field, with a pressure of 300 lb. per sq. in., there would be absorbed 65 cu. ft. of gas per barrel, or 1.55 cu. ft. per gal. of oil. The writer does not know if data have been obtained, by experiment, for pressures beyond those indicated in this article, therefore, for the purpose of illustration, he has projected this curve to obtain figures for pressures greater than 300 lb., although probably experiment will show that the extended line is not quite correct.

Jan 1, 1926

By C. W. Allen, L. C. Moore

The Mather mine, of the Negaunee Mine Co., is within the limits of the City of Ishpeming. on the Marquette iron range in Michigan's Upper Peninsula. It is named for William G. Mather, who has served as President, and Chairman of the Board, of The Cleveland-Cliffs Iron Co. for well over 50 years. The property comprises nearly the square mile of section 2, T.47 N. R.27 W., which, except for 20 acres in the northeast corner, was leased by The Cleve-land-cliffs Iron Co. to the Negaunee company. The latter is a partnership of Cleveland-Cliffs and the Bethlehem Steel Co., organized to equip the property, retaining Cliffs in charge as operator. Shipments of ore from this area are mainly through Marquette, which is 16 miles to the northeast on Lake Superior, or through Escanaba, a Lake Michigan port, 65 miles to the south. Cleveland-Cliffs, in 1943, operated 12 mines in the Lake Superior district, with shipments of 6,635,576 tons for the year. Geology The north footwall of the Marquette Range synclinorium outcrops near the north line of set. 2, the iron formation dipping to the south at an angle of about 40. The south side of the trough reappears at a distance of 4J5 miles on sec. 26 and the surface geology between shows iron forma- tion or intrusive diorites. The latter are harder than most phases of the iron formation and, as a result of glacial action, appear as buttes or low-lying hills. The general elevation of sec. 2 is about 1450 ft. above sea level, or 850 ft. above Lake Superior, and the higher diorite outcroppings about 1600 ft. above sea level. The geological structure has been complicated by a series of major and minor faults, one of which may be illustrated by the diorite sheet, which tilts south with the iron formation in the north half of the section and then reappears near the center to repeat this sequence. Sectionally the geological series includes a nearly eroded capping of Goodrich quartzite followed by the considerable thickness of Negaunee iron formation, which is cut by intrusive dikes or diorite sheets, and underlain by the Siamo slates grading into quartzites. The ore deposits occur mainly in troughs formed by the intersection of impervious dikes and the footwall slate, but include locally enriched lenses or bands in the iron formation and also interbedded with the Siamo slate. The ore is a soft red hematite with an indicated dried analysis from the surface drilling to date of 61.50 per cent Fe, 0.134 Per cent P, 5.40 per cent Si, 2-87 Per cent A1 and 0.015 per cent S. Exploration A diamond-drilling campaign started in 1937 actually had its inception in 1917, when a number of shallow test holes were put down for the purpose of locating ore that might be quickly developed and mined

Jan 1, 1946

By B. S. Butler

PART I SUMMARY CERTAIN relations between the formation of ore deposits and other geological processes are pretty generally accepted, namely: that many ore deposits are closely associated with igneous activity; that ore deposits accompany certain types of intrusive bodies, notably batholiths and stocks, and that they are concentrated near the tops of such bodies; that igneous activity occurs in belts of strong folding and faulting; that folding and faulting are greatest in basins of extensive sedimentation and least in areas of erosion or slight sedimentation; that areas of erosion or slight sedimentation and of heavy sedimentation persist over long periods and exert a major control over structure, igneous activity, and ore deposition; that cycles of erosion, deposition, folding and faulting, igneous activity, and ore deposition, have been repeated through geologic time resulting in rather definite periods in which metal deposits have formed. In short, ore deposition is but one phase of a series of closely related geological events. It is attempted in this chapter to point out the relations of these interreacting geologic processes to the distribution of ore deposits in the western United States. Three great periods of mineralization are recognized; pre-Cambrian, post-Jurassic, and late Cretaceous-Tertiary. In distribution the deposits of the three periods, with certain exceptions, show a concentration about two large positive areas, the Colorado plateau and the Columbia plateau, which suggests a causal relation. The most general age divisions of the rocks of the Cordilleran region of the United States are (1) pre-Cambrian, and (2) Cambrian and later rocks. The pre-Cambrian rocks are exposed mainly through the Rocky Mountain belt from the Canadian boundary southward to Arizona and westward through Arizona to southern California. They have commonly

Jan 1, 1933

ALABAMA Alabama City.-Eddy, L. Altoona.-Cain, J. America.-Foreman, J. T. Anniston.-Foster, R. N. Ashland.-Sturdevant, J. C. Bessemer.-Ball, E. M. Calhoun, F. W. Maschmeyer, W. L. McKenzle, W. C., Jr. Birmingham.-Abbott, C. E. Aldrich, T. H. Aldrich, T. H, Jr. Ashton, J J.

Jan 1, 1923