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By P. C. McLeod

THE GECO OREBODY, located north of lake Superior in the Thunder Bay district of northern' Ontario, was discovered in 1953. Diamond drilling in the following year indicated a 15,000,000-ton ore-body, and production plans were made for the shipment of copper and zinc concentrates in three years. To accomplish this, the Geco Project was initiated. The property was in an undevdoped, inaccessible area, and the project involved the conversion and extension of a logging road to the property, the construction of two railways and seventy miles of hydro transmission line, the erection of a municipality, the building of a plant, and the development of an underground mine to produce 3,300 tons per day. This paper describes some of the methods used in the underground development phase of the Geco Project.

Jan 1, 1958

President Robert M. von Storch, General Superintendent, Coal Mines and Quarries, Columbia-Geneva Steel Division, United States Steel Corporation, Dragerton, Utah, called the meeting to order at 9:30 a.m. in the absence of John Peperakis, Past President, who was usable to attend because of a mine fire. He welcomed the members with a paper entitled "With Serene Confidence." He also showed a short movie, "The Waiting Harvest," with his speech. Following the president's speech, the first business meeting of the Institute was held. Secretary-Treasurer Fred Whiteside presented the Treasurer's Report. Motion made by Mr. Whiteside, second by Stan Shubart that this report be accepted. Motion carried. Because the minutes of the last meeting were published in the Institute's booklet, the reading of the minutes was dispensed with, and the President announced the members of the various committees: General Chairman ? Charles M. Schloss

Jan 1, 1958

By Strathmore R. B. Cooke, Iwao Iwasaki

RECENTLY spectrophotometry has been reported to provide a convenient technique for the rapid and reproducible determination of xanthate concentration in pulp solutions,12 and for a kinetic study of xanthate decomposition in acid solutions." Since the application of this analytical technique is feasible for those compounds showing pronounced light absorption maxima in the near ultraviolet region, it was deemed advisable to investigate the absorption spectra of some of the organic compounds that are used in flotation. It is known empirically that certain groups of atoms in an organic compound cause characteristic light absorption in the ultraviolet and near ultraviolet range, and the wavelengths and intensities of the corresponding absorption maxima are relatively independent of the nature of the remainder of the compound. The characteristic values of such groups, which are known as chromophores, are given in the literature.4,5 According to this information, many of the sulphydryl compounds are expected to show absorption maxima in the near or long wavelength ultraviolet region, whereas the saturated fatty acids and the saturated alkylamines do not. This article reports the absorption spectra of the six following types of sulphydryl compounds; mono-, di-(xanthate), and trithiocarbonates, dithiocarba-mate, dithiophosphate (aerofloat), and mercaptan. A Beckman DU quartz spectrophotometer was used to investigate the spectra in the wavelength region of 215 to 350mp. Materials: All the mono-, di-, and trithiocarbonates used in this investigation were prepared in the usual manner" from appropriate compounds obtained from Eastman Distillation Product Industries. The dithiocarbonates included the normal alkyl compounds from methyl to octyl inclusive, as well as the isopropyl, isobutyl, and isoamyl xanthates. Iodo-metric titration gave 99.7 and 99.5 pct purity for

Jan 1, 1958

By William M. Nabors

As a part of a program to promote conservation and efficient utilization of petroleum resources, Bureau of Mines engineers are studying secondary oil-recovery projects in the United States. Published reports that set forth the pertinent facts of these operations help others to profit by the experience gained. This report presents the results of a study of secondary-recovery methods used in Kentucky by the Cumberland Petroleum Co. on its L. C. Bailey lease, Oil Springs pool, Magoffin County, Ky. This is believed to be the first water-flooding project in eastern Kentucky (fig. 1).

Jan 1, 1958

By Paul B. Crawford, Bobby L. Landrum

An electrical model study has been mode to estimate the effect of horizontal fractures in thick reservoirs on pattern conductivity. For the patterns studied, it is shown that fracturing all the wells in the pattern in-creases the conductivity considerably more than frac-turing only single wells. For certain conditions one large fracture is more effective in increasing conductivity than several fractures of half the radius. Particularly in thick reservoirs and with large fractures, the center of the pay is found to be more responsive than other locations. For the seven-spot pattern fracturing the center well is more effective in increasing pattern con-ductivity than fracturing all outer wells with fractures of the same size. INTRODUCTION Although commercial fracturing has been used for some time very little quantitative information is known about the effects of fractures on reservoir behavior. The purpose of this work was to estimate the effect of horizontal fractures in thick reservoirs on the con-ductivity of various flooding and cycling patterns.2 Circular fractures originating at the wellbore and extending symmetrically into the pay were considered. ANALYSIS Electrical models were used in making this study. Horizontal fractures were simulated by copper sheets shaped like the fractures and of a proportional size; the wellbore was simulated by a copper wire. A dilute salt solution served as a conducting medium. A con-ductivity bridge was used to measure the conductivities of the various patterns studied. EFFECT OF HORIZONTAL FRACTURES ON CONDUCTIVITY Fig. 1 shows the effect on square and staggered line drive patterns of horizontal fractures located in the center of the pay. The model is shown schematically in the insert. The upper and lower groups of lines show the effect on conductivity when all wells are fractured, and when only one well is fractured, respectively. In general, pattern conductivities are substantially improved by fracturing all wells. Fig. 2 shows the effect of multiple horizontal frac-tures on the conductivity of a line-drive pattern. At

Jan 1, 1958

By L. J. Howell, R. C. Sommer, H. H. Kellogg

WORK described herein was undertaken with the aim of determining some of the physical-chemical properties of electrolytes suitable for the electrodeposition of pure zirconium metal. In this paper the phase diagram, vapor pressure, and activities in the melt are considered. In a companion paper,' the electrolytic conductivity of some of these melts is reported. The melts studied were mixtures of NaCl and/or KC1 with ZrC1,. Chloride melts were chosen for study because 1) if the electrolyte is to be useful for industrial electrodeposition of zirconium, the chlorides will be preferred to the relatively costly bromides and iodides; 2) fluoride melts were being studied in another laboratory (Horizons Inc., Cleveland); and 3) melts containing oxygen, in any form, are unsuitable for preparation of pure zirconium, because of the great affinity of this metal for oxygen. Unlike electrodeposition from aqueous solution, the fundamental behavior of fused-salt electrolysis is poorly understood. In most cases, such basic electrochemical information as the phase diagram of the melt system, activities in the melt, conductivity, the nature of the current-carrying ions, the equilibrium electrode potentials, and the overvoltage behavior of the electrodes is unknown to the researcher who would develop a new electrodeposition process employing a fused salt. This research project was designed to supply information about some of these basic physical-chemical properties so that an intelligent choice of electrolyte for electrodeposition studies could be made. Experimental The experimental difficulties-encountered in this work result from the properties of zirconium metal and ZrC1,. ZrC1, is a solid which sublimes at 334°C. It is rapidly hydrolyzed by moist air to HC1, ZrOCl,, and ZrO,. Unusual precautions were exercised in this work to prevent hydrolysis of ZrC1, and rigidly to exclude oxygen, nitrogen, hydrogen, and carbon from the melts under study. These elements are known to react with and contaminate zirconium metal. All melts were studied in vacuum systems, i.e., in the presence of ZrC1, vapor only. Transfer of ZrC1, to or from the melts was accomplished entirely by vacuum sublimation. In this way, neither the melts nor the ingredients thereof were permitted to

Jan 1, 1958

By R. Maddin, S. K. Tung

SUCCESS of the dislocation theory in formulating the transitional lattice theory proposed by Har-greaves and Hill in 1929' is well established for low angle grain boundaries. The theoretical work of Burgersa and Read and Shockley,3 together with the experimental observations of Aust and Chalmers4 and Parker and colleagues,6 leaves little doubt as to the structure of grain boundaries with differences of orientations up to between 15" and 20". Beyond these angles, the structure of the boundary is not so clear, and is still a matter for conjecture. There have been notable experiments devised from which the data could be used to calculate energetics for possible arrangements of atoms in forming a large angle boundary.6 Most of these experiments deal with diffusion through and along the grain boundary. The recent work of Rhines and Cochart7 and Rhines, Bond, and Kissel18 was concerned with the relative movement of grains in aluminum bicrystals under constant tensile loads with their boundaries aligned at 45 " to the tension axis. The gliding along the grain boundary was cyclic and began after an incubation period. The velocity of gliding increased with the sum of the angular difference, 8, between the operative slip direction in the conjugate crystals and the angular difference between the active slip planes as measured between their traces upon the grain boundary. The initial gliding rate varied with temperature, and the logarithm of the average gliding taken over a considerable period was a linear function of the reciprocal of the absolute temperature: the slope gave an activation energy of 11,000 ±1,000 cal per mole. Since the rate of grain boundary shear is sensitive to the misorientation of the grains themselves, as shown by several workers,7,8 it is suggested that further work of this type might be fruitful in adding information regarding the behavior of boundaries under stress. The techniques devised by Chalmers" added impetus to the facility for observing grain boundary behavior, in that they provided a simple means for producing bicrystals of predetermined orientation so that the angle of the boundary could be controlled,

Jan 1, 1958

By A. A. Wallach

During the early design stages of the San Manuel Concentrator, numerous questions were raised concerning the required slope for tailings pipelines. The tailings disposal area which had been selected was so situated, that an average down-slope of 5% existed. A gravity tailings disposal system was to be designed and it was necessary to determine the optimum pipeline slope for design purposes. This information was also necessary to determine the life of the available disposal areas before tailings pumping would be required. At approximately the same time as this problem arose, it was reported that a concentrator in the southwest was having considerable operational difficulties due to periodic plugging of tailings lines. These factors combined made it seem desirable to conduct some sort of test work which might give information concerning the flow characteristics of the tailings to be produced, from the San Manuel Concentrator. It was felt that the maximum information could be obtained if a tailings line could be erected which would allow for varying slopes, varying heads and accurate measurement of pulp velocity. A five-foot Denver Agitator was installed on a bank overlooking a cut for a rail- road track. Approximately 160 feet for new &-inch pipeline with victaulic connections was installed on low trestles along the track, with provisions made for varying the slope of the line by use of accurately constructed sets of shims, A valve discharge was installed on the tank so agitated pulp could be run into a standpipe at controlled volumes. This standpipe was 10 inches in diameter and approximately 5 feet high. A 4-inch nipple welded into the side of the standpipe approximately one inch from the bottom was connected to the 4-inch pipeline. At the discharge end of the 4-inch pipeline a launder arrangement was so constructed that the entire discharge could run into a pump sump or into 50-gallon measuring vessels. In normal operation the flow was from the agitator to the standpipe through the pipeline into the pump sump and from there pumped back to the agitator tank.

Jan 1, 1958

By R. A. Campbell

Pig iron and silicospiegeleisen were produced experimentally from a very low-grade manganiferous iron ore from Steep Rock, Ontario, by a two-stage electric smelting process. The most favourruble operating conditions were determined for each stage. Cement clinker then was made by calcining the slag from the second stage of smelting, with additional limestone and alumina. (This slag would normally be a waste material). The cement clinker produced had the composition of commercial Portland cement, and met the physical test requirements of the Canadian Standards Association Specification A5-1951 for normal Portland cement as well as could be expected for a material produced on .such a small scale.

Jan 1, 1958

By W. T. Wertman

A research program to aid development of better and more efficient methods for producing petroleum and increasing its ultimate recovery from underground formations is an integral part of the work of the Bureau of Mines on conservation of the Nation's natural resources. Economic, efficient production of recoverable oil and gas from a reservoir depends to a great extent upon the best and most accurate information that can be obtained from a study of the reservoir rock and its fluid contents. Information on oil and water saturation is pertinent and essential in wildcat, extension, and pool wells for good reservoir operations and prediction of performance. This report presents results of an investigation by the Bureau of Mines of core recovery and degree of drilling-fluid contamination occurring during cable-tool coring operations using oil-base mud. Representative core samples were obtained from 6 major oil-producing sands in 8 fields of West Virginia, Pennsylvania, and New York. Field-mixed, oil-base drilling mud was used for the first coring test, and lightweight, premixed oil-base mud, with an organic chloride tracer added, was used in coring eight other wells. Tracer analyses were made to determine contamination of core by drilling-fluid filtrate. Core analyses, including oil and water content and minimum interstitial water-saturation tests, were made on selected core samples to compare and evaluate water saturations determined by the two methods.

Jan 1, 1958

By M. I. Sherman, J. D. H. Strickland

PRELIMINARY experiments in these laboratories showed that whereas pyrite1 produced only sul-fate the action of aqueous chlorine solutions on most other sulfide ores resulted in the formation of a mixture of sulfate and elemental sulfur, the production of the latter being favored by a very dilute solution of oxidant. The reactions taking place were obviously complex and only a detailed kinetic study could be expected to clarify the position and enable a prediction to be made of conditions leading to the rapid formation of metal salt and the economically desirable elemental form of sulfur. Galena was chosen for the first investigation as it is of widespread occurrence and is representative of a simple cubic lattice sulfide containing the monosulfide unit, S2-. Experimental Procedure The apparatus and general technique used in this work have already been described.' Analyses for chlorine and sulfate were carried out by the same methods as those used for pyrite. The lead in 1 ml aliquots of solution was determined polarographi-cally, after destroying chlorine with hydrazine hy-drochloride and making solutions 0.5 molar with hydrochloric acid. A large sample of Kansas galena, assaying at better than 98 pet PbS, was crushed and wet sieved to give fractions of —10 + 14, —20 + 28, —28 + 35, and —48 + 65 Tyler screen. The particles were almost perfect cubes and the apparent surface Per gram was calculated assuming each particle a cube Of side equal to the mean mesh opening. A volume shape factor, calculated as for pyrite, was exactly unity. The main apparatus was unsuitable for direct visual examination of the ore particles during the reaction. For this purpose a small cell from a Spekker Absorptiometer optical flats 1 cm apart) was l by a greased microscope slide after filling with oxidant solution. One or two ore particles were placed in the cell and the solution was stirred by a glass covered speck of iron wire activated by an external rotating magnet. The surface of an ore particle was examined under a binocular microscope at between 10 and 40 magnifications. Results Experiments were made under a wide variety of conditions, the form of presentation of the data being illustrated by Fig. 1, where the concentrations of chlorine, sulfate, and sulfur are plotted against time. The fictitious concentration of solid sulfur is used for convenience and is the molarity of sulfur which would be recorded if the elementary sulfur formed during the reaction were dissolved in the liquid iii the reaction vessel. As some lead sulfate is occluded with the sulfur on the ore particles the amounts of sulfur and sulfate formed during a reaction cannot be calculated

Jan 1, 1958

By A. Dreimans

Tracing of 'float' against the latest ice-flow directions ha!' led to or assisted in discoveries of several mineral deposits in Canada at lP.ast since 1891, e.g., fluorite and corundum in eastern ?Ontario, Steeprock and Josephine iron ore in western Ontario, Malartic, Fisher-Quebec, and Lamaque gold ore, and Vendome zinc ore, in western Quebec, Sullivan zinc and lead sulphides in British Columbia, Orvan Brook or New Calumet sulphide deposit in New Brunswick, Lynn Lake nickel sulphide de-posit in Manitoba, etc. Pebbles or ore boulders whose source has not yet been found include diamonds in the Great Lakes region and ?sulphides in several localities in Ontario and Quebec. Complexity of transport of ore boulders, including non-glacial transport, may be the explanation. Tracing of ore boulders requires knowledge of the Pleistocene history of each particular area (ice flow directions, their ?changes during glacial oscillations, existence of pre-glacial lakes with ice-rafted boulders, later interference by streams, lakes, mass movements). Important also is distinction of till from similar non-glacial deposits and knowledge of the bed-rock geology. Quantitative methods, e.g., pebble counts, maybe applied while tracing magnetite, hematite, or goethite. Fragments of sulphide ores are less abundant in indicator trains, and quantitative methods are less suit-able for tracing them. Heavy-miner-al investigations may give good results for minerals resistant to weathering. Geochemical methods are of value only in the vicinity of ore deposits.

Jan 1, 1958

By A. F. Henderson, C. F. Cornell, A. F. Dunyon, D. A. Dahlstrom

IN processing magnetic taconites several steps of crushing, grinding, classification, and magnetic separation are required to produce a 60' pct Fe concentrate. Usually the final concentrate is in a slurry form of 55 to 70 pct solids by weight and is further characterized by a particle size of 60+ pct —325 mesh. In taconite plants already completed or under construction the conventional method used to obtain pellets suitable for blast furnaces is to filter the concentrate slurry, ball the filter cake, and then harden the green pellets in a traveling grate or in a vertical shaft furnace. Large tonnages must be handled in minimum floor space, with reduced maintenance and lowest possible operating cost. Filtration must therefore achieve two objectives: I) high filtration rate—in terms of pounds of dry solids per hour per square foot of filtration area—at a low filtrate solids concentration, and 2) a filter cake moisture that will always permit efficient balling within the normal fluctuations of ' plant operating conditions. If moisture contents are too high, balling may be impossible or result in a mushy ball .without enough green strength for the firing operation. Development work has met these objectives. At low investment and operating costs, filtration rates of 250 to 600 dry lb per hr per ft2 have been attained for concentrates of 60' pct —325 mesh. By combining the disk-type continuous filter with proper agitation, the Agidisc filter produces a homogeneous filter cake, easily discharged from the disk sectors. This application provides the lowest initial cost per square foot of filtration area, minimizes floor space, reduces down time for changing filter media to a negligible factor, and simplifies process control and maintenance for the operator. It is now possible to predict very closely the taconite concentrate filtration rates for a wide variety of conditions—either by experience or with a few simple leaf tests. When balling and pelletizing operations began on a continuous basis, it became apparent that moisture content of the filter cake was a critical factor and must always be controlled by the filter operator below some maximum allowable value. Accordingly the Reserve Mining Co. and the Eimco Corp. joined in a study of the many variables affecting filter cake moisture content. The study was conducted at the Reserve Mining Co. taconite plant at Babbitt, Minn. To process plant tonnage the Babbitt plant utilizes a 6-ft diam Agidisc filter with six disks and an 8-ft diam drum filter with 10-ft face. However, most of the plant filter investigations were made on the Agidisc because of its superior performance. A considerable amount of small-scale test work was first carried out to study more closely the individual variables and ascertain their effect on filter cake moisture content. A general correlation method was then developed which allowed reasonable prediction of moisture content at any operating conditions. This step was made necessary by the fact that in full-scale filtering, operating variables usually interact to produce a combined rather than a singular effect. Studies were then made on the full-scale filters to prove the validity of the correlations developed, and past operating records were examined to ascertain whether or not significant variations could be traced to any single factor or to a combination of factors.

Jan 1, 1958

By A. L. Engel

High extractions of lead, gold, and silver resulted from treatment of an oxidized, arsenical refractory ore by chloride volatilization. The ore was roasted in an oxidizing atmosphere at 1,000° C. for 1 hour. The chloridizing reagent was 300 pounds of CaC12?2H20 per ton of ore. Ninety-nine percent of the lead, 98 percent of the gold, and 96 percent of the silver, and only 6 percent of the arsenic, were volatilized. These results indicated that a satisfactory method could be developed for treating this type of ore. Recovery and separation of the volatilized values and developing metallurgical and operating data for this process require further investigation on a more extensive scale. Tests by gravity concentration, flotation, and cyanide leaching did not give satisfactory results.

Jan 1, 1958

By J. M. Hollicky

The economical processing of wet and sour natural gas presents a problem due to the seasonal demand for natural gas. The plants must be sized to handle the peak loads but may only operate at half capacity on the average, in which case the sales value of sulphur and hydro-carbon liquid by-products cannot support the operating and capital costs of the plant. This must result in an increased price for the gas. This problem was solved by Pacific Petroleums and Westcoast Transmission in the design of their pipeline and plant facilities now operating in the Peace River area, where there are both wet and dry gas fields. By .building a plant to process sufficient wet gas to pro-vide the base load requirement, and by drawing on the dry gas fields for peak loads, an optimum economic operation was ?possible. The sulphur, L.P.G., and gasoline produced not only are able to support the operating and capital costs of the pro-cessing plant, but were instrumental in the sharp drop in retail prices of these commodities in the area. The sour gas and condensate is gathered from the fields in the area and transmitted in a two-phase gathering system to the gas processing plant at Taylor, B.C. The condenrnte is knocked out in inlet scrubbers. Hydrogen sulphide and carbon dioxide are removed in an amine scrubbing unit. The hydrogen sulphide is stripped from the amine and is sent to the Jefferson Lake Sulphur Company's plant which produces sulphur by the partial oxidation of the hydrogen sulphide. The natural gas, now sweet, is processed in an absorption unit to recover additional liquids, before being de-hydrated to remove water. It is then sent to Westcoast's main c8mpression station. The condensate recovered in the inlet scrubbers and the liquid re-covered in the absorption unit are fractionated to remove fuel gas, used in the plant, and to produce pro-pane, butane, and naphtha. The pro-pane and butane are scrubbed with caustic soda to remove hydrogen sulphide. The naphtha is treated with hydrogen in a unifiner unit to re-move sulphur compounds completely, and is split into a light and heavy naphtha. The heavy naphtha is .catalytically reformed to produce a high-octane blending-component. These fractions are blended with components produced from crude oil at the Dawson Creek refinery to produce a high-quality balanced gasoline with special attention being paid to volatility for ease of starting, warm up, and engine cleanliness, and octane for power and ?performance.

Jan 1, 1958

By Rikuro Otsuka

TITANIUM is attacked slowly by hydrochloric acid," and corrosion rates decrease with time of exposure.' This behavior is due to the formation

Jan 1, 1958

By Lewis J. Patterson

In the period of time allotted to this paper, an attempt will be made to cover a great deal of territory, figuratively speaking, as far as our experience with ammonium nitrate is concerned. In giving this subject the "broad-brush" treatment, it will be necessary to generalize on the major points which at the same time will permit me to avoid, to a great extent, any involvement in the purely technical and theoretical aspects of blasting. The practice of theorizing before a new idea is tried has practically been discontinued in our organization simply because experience has shown that, almost without exception, theories have fallen aside as some new development takes its place. In regard to blasting, logic and experience seem to have little place in this phase of quarry operations. As the use of low cost blasting agents was introduced in our operating practice, a man who had no previous experience in the field of blasting but with sound knowledge in safety procedures was given the responsibility of supervising the drilling and blasting operations. A total lack of experience is not ordinarily recommended as a prerequisite to assuming the responsibilities of a supervisory position. However, in this case it was obviously a wise decision because there were no pre-conceived ideas as to what techniques would or would not be successful.

Jan 1, 1958

By Earl A. Berry

Someone once said, "The safest mine is one in which no one goes into." We all recognize this as being perhaps wishful thinking. We also recognize in it a certain amount of truth and an ultimate goal if we are optimistic. All of us are aware of the many things that have been done, are being done and will be done to reduce manpower in mining. For those of us; who are optimistic about this ultimate goal it would appear from the records-we are more than well on our way to the so called safest mine. Let us see what has been done in the past 20 years. T e period from 1935 to 1956. For example in the coal mining industry: In 1935 there were employed 462,903 men who produced an average of 805 tons per man per year or 4.50 tons per man per day. In 1955 there were employed 225,093 men who produced an average of 2,064 tons per man per year or 9.84 tons per man per day. There are no comparable figures compiled for the metal mining industry as a whole that can be broken down in this manner. However, from examination of figures available for different groups in metal mining there is a trend similar to that in coal mining. No-dbout the above figures reflect the intense development and perfection of machines and mining systems to tear out, transport and process our mineral wealth. The figures also show the mining industry has been able to double its production and at the same time reduce its manpower by half. When you compare the number of men employed today with the number which would have been employed 20 years ago to gain todays production at that time it become apparent that greater safety has been accomplished. For example the years 1935 to 1956 for all mining show. In 1935 there were approximately 649,226 men employed in mining and reports show 1,399 fatalities and 74,913 non-fatal injuries. In 1955 when there were 313,883 men employed in mining 496 fatalities and 25,365 non-fatal injuries were reported. To have produced the same tonnage of material in 1935 that was produced in 1955 it would have required the employment of approximately 1,298,452 men. 2,798 could have been fatalities and 149,826 could have had non-fatal injuries. You can now measure the full impact of what has been accomplished in the past 2o years by the aggressiveness of mine management, the wizardry of our engineering personnel and the thoughtfulness and devotion of our safety people and their programs. Therefore, there is a trend towards the goal of our opening statement. We whoare toptimistic believe this trend will accelerate at a-faster pace. Why? Because anyone engaged in the mining industry today can well afford to invest a minimum of $30,000.00 in capital equipment todisplace the labor of one man. This fact alone is a terrific incentive for mine management to apply and manufacturers to develop equipment of a type to get the men out of the mine. Now you can determine this problem not only becomes one of safety but also one of economics, When productivity is stepped up and manpower reduced management is learning the hard way what it means to them; in the profit and los s column when a few minutes of delay or downtime of costly machines and processes occur. They have learned that fast and efficient communication systems are the best means of combating breakdown, delays, bottlenecks, supply problems, the saving of lives and property and increasing production. One large western metal mine was able to increase Its tonnage by 4000 tons a day by using modernup to date electronic type communication system. The National Coal Board of Great Britain recently allocated 45,000,000.00 to study and develop faster and more efficient communications when a survey indicated what a serious bottleneck poor communication in their present systems of mining turned' out Lobe.

Jan 1, 1958

By Ernest L. Ohie

In 1939 the Geological Society of America published a summary of the geology of the ore deposits of the Mississippi Valley region, This volume, edited by E. S. Bastin, contained contributions from the foremost students of the area which described theregionalgeologic setting of the various deposits as wel as the detailed geology as then known. The various ideas as to the origin of the ores were discussed with the general, though not unanimous, conclusion that the deposits were hydrothermal products, Only those deposits in the immediate Mississippi Valley area were considered without any attempt to introduce evidence from other districts generally accepted as being of the "Mississippi Valley type." Since 1939, much new information has come from extended studies of two of the important districts described in the 1939 report andimportant extensions of the known ore have been found. Likewise, concentrated geologic efforts have been fruitful in severa "Mississippi Valley type" districts - both U. S. andforeign - not treated in the 939 paper. The wealth of new field information on the structural and stratigraphic relations of this interesting ore type, coupled with the results of theoretical and laboratory studies of the past 18 years, makes desirable a review of our present knowledge and interpretation of these important deposits which for many years have yielded over 20 percent of the world's annual production of lead and zinc, together with large amounts of fluorspar and barite. No restatement of the details of the geologic evidence willbe attempted here; the interested student is referred to the papers cited. Slide No. 1 shows the distribution around the world of the deposits under consideration. A principal thesis of my remarks is that there is so much similarity in all these deposits that it seems necessary for all of them to have had a similar mode of origin, whatever that may be. Variations in the shape, size and mineralogy of the orebodies give each district some individuality, but there are enough of the "typical" characteristics present in all cases to make classification in the "Mississippi Valley type" agreeableto most geologists. Thus the overall process giving rise to the ore solutions surely was the same for all in the group. Either they all have igneous affiliations or they all do not. Acknowledgment of this kinship between deposits in the various districts offers many advantages in trying to arrive at a decision as to just what the origin may have been, for the amount of guiding and limiting evidence which must fit into the hypothesis is greatly increased over that available in any one district, To a certain extent this was recognized by the authors of Special Paper 24 in treating all of the immediate Mississippi Valley areas together; by expanding the consideration to include ore deposits of this type all over the world the changes of success, i.e., arriving at the correct answer, are improved several fold. Since most of these districts are quite simple structurally, a number of hypotheses might fit the facts in any one of them, but if the facts to be met can safely be drawn from all the districts, then the explanations which will fit all the data are much less numerous. One purpose of this paper is to call attention to the field facts that have been reported from the .various areas which seem to have an important bearing on the kind of ore fluid that was responsible for the ore and on the way it circulated.

Jan 1, 1958

By N. A. McKinnon, J. H. Auld, A. M. Marshall, R. A. Coyle

IN making a study of the slip deformation and strain hardening of single crystals of aluminum, it has been found that considerable information additional to that provided by the usual metal-lographic techniques can be obtained by the use of the microfocus X-ray method described by Schulz.1 This technique has been applied to crystals both in the state as-grown by the strain-anneal method and after they have been subjected to increasing amounts of plastic strain. Kelly and Wei" have recently reported the use of this method for a study of lineage structure in aluminum single crystals grown from the melt. The crystals, prepared from aluminum of 99.99 pct purity supplied by British Aluminium Co. Ltd., were grown in the form of flat tensile specimens with a gage section of 0.3 by 0.1 in. and a gage length of 2.3 in. The microfocus X-ray tube used provided a focus of approximately 50 half width. Examination of a large number of as-grown crystals showed no sign of any macroscopic defects in the majority of cases. However, occasionally crystals grown by the strain-anneal method did show defects similar in nature to those shown by Kelly and Wei to occur in crystals grown from the melt. In some other cases a more regular appearance of black and white lines, corresponding to valleys and ridges, respectively, in the lattice, was obtained, Fig. 1. This particular crystal was slightly deformed as the lines when present in the image of an as-grown crystal are only barely visible. The angle of tilt of the blocks is of the order of 3. It seems likely that these tilt boundaries arise during the growth of the crystal due to the specimen not being perfectly flat on the hearth of the furnace and straightening under its own weight at the elevated temperatures. For the deformation studies the crystals were strained in a Polanyi-type tensile machine. A typical photograph taken after 1.2 pct elongation of a single crystal oriented with its axis fairly close to the center of the stereographic triangle is given in Fig. 2. The reflection, which is from the (111) planes, is traversed by two systems of parallel lines. These have been identified as traces of the primary (111) slip plane and the (110) plane perpendicular to the primary slip direction. The latter lines correspond to kink bands which could not be detected by the ordinary techniques of

Jan 1, 1958