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By Charles R. Keyes

Prefatory,........323 Foundation of classificatory schemes in general..325 Past opinion on the classification of ore-bodies,.326 Nature of ore-deposits,....... 326 Definition........326 Fundamental law of origin.... 327 Significance of ore-bodies,.... 327 Date of origin........328 Original source of ores..... 328 Alteration of ore-bodies,....329 General methods of ore-formation.... 330 Ascension verm lateral secretion... 330 Replacement.......330 General factors in classification....332 Genesis in ore-classification....332 Literature of ore-deposits...... . 333 Criteria of ore-classification,..... 335 Primary grouping of ore-deposits..... 338 Hypotaxic deposits......341 Eutaxic deposits...... 341 Ataxic deposits....... 313 Secondary categories of ore-bodies....343 Ternary phases of ore-deposition.....344 Types of hypotaxic or surface deposits..... 344 Illustrations of eutaxic ore-bodies.... 347 Examples of ataxic ore-bodies.....352 Recapitulation.. .. .. .. 355 Prefatory. Much has been written on the genesis and classification of ore-deposits. Much remains yet to be written on the subject

Jan 1, 1901

By S. A. Allison, N. P. Finkelstein

After a brief consideration of the properties of zinc sulfide minerals, their flotation characteristics, and their reactions with thiol collectors, the literature on the activation of the minerals by cupric ion, their deactivation by cyanide, and their depression is reviewed in detail. The distinction between deactivation and depression is stressed. The contradictions in the published results and theories are discussed and attempts are made to resolve them. It is concluded that, whereas all aspects of the subject require further investigation, the study of depression is most likely to yield benefits in practice.

Jan 1, 1976

J. D. Fast and J. L. Meijering (Philips Research Laboratories, N. V. Philips' Gloeilampenfabrieken, Eindhoven, Netherlands)— After the departure of our friend Dijkstra to the United States, investigations on the effect of alloying elements on the behavior of nitrogen in a iron were continued in Eindhoven. We too found internal friction curves with two separate peaks for iron containing nitrogen in addition to 0.5 atomic pct V or 0.5 atomic pct Mo. Our first publication on these investigations" appeared almost simultaneously with the paper now under discussion. At first sight our experimental results seem to be in harmony with their conclusions, but a closer examination reveals that in the case of the Fe-V-N alloy the abnormal peak is not controlled by one time of relaxation only. Whereas iron containing 0.5 atomic pct Mn or Mo absorbs an amount of nitrogen of about the same magnitude as that absorbed by pure iron under identical conditions, iron containing vanadium absorbs in addition one nitrogen atom for every vanadium atom. This last amount, far exceeding the first amount in the case under consideration, combines chemically with the vanadium and causes no internal friction. The "free" nitrogen in the vanadium alloy gives rise not only to a damping peak corresponding to that in pure iron but— due to the presence of VN particles in the metal—also to the abnormal peak at higher temperatures. The VN particles create interstitial sites around themselves where the free nitrogen atoms are bound much tighter than in the normal interstices. These abnormal interstices, therefore, will capture free nitrogen atoms rapidly, whereupon these give rise to the abnormal damping. The binding energy in the abnormal interstices is not the same for all, and with coarsening of the VN precipitate the distribution of these energies is displaced toward the side of stronger binding. This is deduced from a shift of the summit of the second peak toward higher temperatures (from 80" to 88°C in our experiments) caused by prolonged heating at 950°C. From the intermediate state where they cause the abnormal damping, the nitrogen atoms pass over rather rapidly into the fully precipitated state (iron

Jan 1, 1954

By W. M. Weigel

WHILE electric lamps both of the cap and hand type are being introduced into many mines requiring the use of safety lamps, the oil-burning safety lamp is still used in the great majority of cases, and even where the former are used the latter must continue to be employed when testing for gas. It is not the intention to discuss here the relative merits of the two types, but simply to give a comparison of the illuminating effect or candlepower of several kinds of ordinary safety lamps used for general work and for testing. Few data have been published in recent years on this subject and because of this it is hoped that the following information may be of some interest and value. The lamps tested were in all cases. of standard size and in good condition, all practically new, and were selected from a collection of about 100 with a view to obtaining results on as many different common types as possible. With the exception of the gasoline-burning lamps, five different oils were used in each lamp to determine whether -particular oils were suited to particular lamps and whether there was any great difference in the illuminating power of the different oils, or whether some oils would maintain their illuminating power better than others throughout a working period of 8 hr. No attempt was made to determine the amount or cost of oil burned by each lamp, but the condition of the lamp, wick, glass, and gauzes was noted after each test.

Jan 8, 1916

By David Kramer, Cecil G. Rhodes

Critical transport currents were measured as a function of perpendicular external magnetic field in Ti-22 at. pct Nb wire samples. These samples were heat-treated to yield w Phase precipitates at denslties ranging from 10 to 10 17cm-3. The Precipitates are ellipsoids of revolution with major axes of 50 to 1300A. Flux-Pinning by w precipitates is responsible for the high critical transport currents that were ob- ThE ability of a type II superconductor to sustain a zero-resistance transport current (Jc) in an external magnetic field (H) is due to the presence of micro-structural features which can impede the motion of magnetic flux penetrating the superconductor under the influence of a Lorentz force. Such features are referred to as pinning sites. The pinning strength is tained. A sample cooled from 800°C and annealed 1 hr at 450°C carried a critical tramport current of 10 amp per sq cm at 30 kG. Variations in the current-carrying ability of this alloy are due to changes in its pinning strength which is a function of precipitate density and composition and of the composition of the matrix. the reaction of the bulk superconductor to the Lorentz force and depends on the efficiency of the individual pinning sites and on their volume density. The super -current density increases with pinning strength, other things being equal. The above concepts are discussed in detail in a comprehensive review by Livingston and Schadler.' In Ti-Nb alloys, as in other binary titanium alloys, the metastable hexagonal w phase usually forms below the p/a + p phase boundary near the titanium side of the phase diagram. Stiegler et a1.' have summarized much of what is known about w phase in titanium and zirconium binary alloys. The present work deals with

Jan 1, 1968

By William A. Edmiston, R. E. Grace

A simplified model for the theory of reaction rates near equilibrium has been applied to the reduction of wustite. A linear relationship between the net rate of reaction and the Gibbs free-energy change, ?F, is predicted. The reduction of wustite in H2 -H2O gas mixtures was studied with a microbalance technique at temperatures from 850° to 950 °C. The predicted model was found to be valid to -?F/RT = 0.1 or approximately -200 cal per mole away from equilibrium. ThE theory of reaction rates near equilibrium has been developed by a number of authors. Prigogine, Outer, and Herbo1 have studied the catalytic hydrogena tion of benzene in an attempt to deduce some intrinsic connection between reaction rates near equilibrium and thermodynamics. Manes, Hofer, and weller2 have derived more general expressions for reaction rates near equilibrium from classical thermodynamics. Hollingsworth3,4 has commented briefly on the work of Manes et al. Benson5 has summarized in a general way the results of the earlier contributions. It is the purpose of this paper to apply the theory of reaction rates near equilibrium specifically to the reduction of wustite in H2-H2O gas mixtures. The basic premise is that the reduction of wustite proceeds by a surface reaction, rather than by solid-state diffusion ,or gaseous diffusion. Richardson and Dancy6 and Gellner and Richardson7 have suggested that the reduction of wustite may be governed by iron diffusion in wustite. Mckewan8-11 has proposed that reduced iron layers on various oxides are sufficiently porous to offer a negligible impedance to the reducing gas. The linear motion of interfaces reported by McKewan and discussed by Themelis and Gauvin12 indicates the lack of diffusive control during reduction. The reduction studies of magnetite reported by Quets, Wadsworth, and Lewis13 give additional evidence that reduction rates are linear when the reaction products are porous and nonprotective. The interpretation of measurements reported in this paper is predicated upon a surface-controlled reduction reaction, at least in the earliest stages of reduction when the reduced iron layer is thin.

Jan 1, 1967

By Keith G. Kirk, Lawrence E. Welborn, Patrick A. Ley

Over the past two years the Office of Surface Mining in conjunction with Energy & Minerals Technology Assessment, ENCORE Systems Inc., and Boeing Computer Services has developed the Economic Coal and Ore Reserve Estimation (ENCORE) Coal Seam Modeling System. This system is being used by OSM, certain states, and industry for mine planning and mine plan permit review. The ENCORE system enables the mining engineer to start at the reserve estimation stage of surface mine planning and continue through the entire mine planning process and into the permit preparation process. The ENCORE system enables the state and federal regulatory authorities to assess a given mining and reclamation plan permit application in a rapid and efficient manner and greatly speeds up the mine plan review and permitting process. The ENCORE system is user friendly and menu driven thereby permitting the engineer with minimal computer training to rapidly learn and utilize the system. Data are input both through digitized map files and bore hole information files and stored in a data base that is an integral part of the ENCORE system. The system performs reserve estimation through standard polygon methods, least square methods, and geostatistical (kriging) techniques. Geostatistical routines permit rapid evaluation of coal and overburden quality and quantity. System outputs include drill hole sumnary and resource summary reports, cross sections, isopach maps, structure contour maps, premining topography maps, postmining topography maps, and three-dimensional perspective views. The maps can be displayed on a high-resolution, color graphics terminal or generated by a high quality plotter and are suitable for direct inclusion in the mining and reclamation pl an permit application. This paper gives detailed examples of ENCORE'S use together with example outputs.

Jan 1, 1983

By Thomas F. Torries, George H. K. Schenck

Crushed and broken stone is used directly in construction as an aggregate and accounts for about half the value and two-fifths of the quantity of natural aggregates consumed in the United States. Sand and gravel provide most of the balance of aggregates except for some lightweight materials such as pumice and expanded shale. Conditions necessary for production of crushed stone from a deposit are : 1) Quality-should pass rigid specifications for strength and durability. 2) Cost-low average total delivered cost. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass either (1) by the addition of cementing or binding materials that produce a concrete or (2) by compaction or by natural weight to produce a road base or foundation. Aggregates usually provide about 80 to 100% of the material volume of the construction masses in which they are used. The construction industry utilizes as aggregates about 70% of all crushed stone produced in the United States according to statistics provided by the U.S. Bureau of Mines (USBM) , [Table 1], using definitions as shown below. Nonconstruction uses of crushed stone, [Table 2], are included elsewhere in Industrial Minerals and Rocks because such uses require the special physical or chemical characteristics which are discussed in those chapters.

Jan 1, 1975

By B. G. Slay, J. P. Pritchard, J. T. Pierce

A short discission is given of the cryotron us a supercozductitzg- switch. The parameters of interest such as gaiz, critical gate current, critical control current, and critical surface current density ave described. The photomask-photoresist process makes possible the study of much narrower dimensioned cryotrons than previously possible using mask stencils. Data is given for the above parameters as a function of width, thickness, temperuture, and crossing ratio. Photographs of the various circuits used are shown. The techniques involved in making connection to the circuits and the precautions taken to avoid side effects in the measurements are discussed. In particular data is given for critical currents of sipercotzducting. lines down to 2X 104 in. A vise in critical surface current density is obserced jor the strallev lines in both lead and tin. A discussion of the ihact of these measurements in the design of future cryotron circuitry is given. In addition to the improvement in device density achieved by simple scale reduction. additonal gains in density may result through improved device form factor. THE cryotron is a superconducting current switch, invented by D. A. Buck.' Fig. 1 shows a typical crossed-film cryotron. Usually the gate is made of tin and the control is made of lead. The critical gate current, is the current that drives the gate resistive with zero current flowing in the control. The critical control current, I is defined as the current in the control necessary to switch the gate resistive with a small monitoring current in the gate. The gain of the device, G, is defined as Since for uniform thin films G should be proportional to the gate width divided by the control width, it is convenient to define the critical surface current density, Jcg, to be the critical gate current divided by the gate wldth. The data which follows will show that, for a given control width, I, is relatively constant. Thus, by measuring Jcg the change in gain as a function of gate width may be measured without measuring I,.

Jan 1, 1967

By R. E. Hook, R. L. McGaughey, A. M. Adair

The initial yielding characteristics of a vacuum-melted iron have been measured as a function of thertnal history after slow cooling or quenching from a 700°C recrystallizntion anneal. A thermal history favoring the segregation of interstitials to grairz boundaries results in a material having high values of upper and lower yield stress and long, irregutar Luders' plateaus, wheueas specimens treated to minimize grain boundary segregation have significantly lower values of these yielding characteristics. The struc- ture of typical grain boundary areas as revealed by electron transmission microscopy is consistent with these findings. The grain boundaries in iron are considered to be principally responsible for the release of dislocations during macroscopic yielding and it is suggested that strong locking results when a substantial amount of grain boundary segregution is present; it follows that weak locking results from a more random distribution of interstitials to grown in dislocations. RECENT years have seen an increased emphasis placed on a more quantitative study of the influence of grain boundaries on the yield behavior of bcc metals. The earlier picturk of dislocation pileups at grain boundaries building up a sufficient stress concentration to unlock dislocations in neighboring grains1

Jan 1, 1967

By T. Egleston

The origin of gold both in placer deposits ancl in veins, and especially the origin of nuggets, has been the subject of repctated discussions and investigations, which have been recently brought to my attention by several extremely interesting specinlens sent to me for examination, and mare especially by the one exhibited at the meeting of the Institute in February, 1880.* In the year 1874 I made some exan~inations of the hydraulic mines of California, and was very nluoh struck with the distribution of the gold throughout these deep placers, which were almost invariably poor on'the surface, while gradually growing richer towards the bedrock. The constant presence of fossil wood, and the large quantity of organic matter contained even low down in these beds, was also remarkable. Not being satisfied with the various theories advanced to account for the formation of these deposits, I began an investigation early in the pear 1879 on the conditions of solubility of gold and the causes of the loss in working gold ore in a large way. The researclles which I have undertaken show that gold must be considered a soluble rather than an insoluble metal, and that the conditions of solution are such as will be found anywhere where gold is likely to occur, and the solution may take place even under the ordinary circumstuncee of surfiace drainage, and may be going on freely even where the presence of gold has never been suspected, and that there are causee enough in nature to produce the solution of the gold in sufficient quantities to account for all the phenomena of both the vein and placer formations. The general theory with regard' to the formation of these placer deposits and nuggets has been that they were the result of the deatruction of pre-existing. vein-matter, which does not accord with the fitcts as sholvn in the deep placer deposits. The gold in such case would be distributed in layers of unequal richness throughout

Jan 1, 1881

By Thomas Adair

Moderator-Thomas Adair is now a tunnel consultant with Perini Corp., Spring Lake, N.J. He has had 40 years experience in tunnel and shaft-sinking work in both soft and hard rock, as well as subaqueous rock. He has used moles in various locations and has traveled around the world studying the problems. SOME BRIEF COMMENTS ON "MOLES" by Thomas Adair We of the Perini Corp. have been, over the past 15 years, in the forefront of the battle to develop the mechanized miner. We have contributed much to pioneer, develop, and promote the use of the mining machine. Our money and talent have not been spared in this effort. However, we are sorry to say that as of the present time (1968), at least from the economic stand- point, this effort has not been very rewarding. But, I must say to those who are presently involved in the work of building mining machines, do not be discouraged. There is money in it. We of Perini Corp. know because we put it in there. It has been estimated that during the next 15 years, some $20 billion will be spent on underground excavation; more than 13 thousand miles of sub- surface tunnels will be excavated throughout the nation. An aggressive, properly structured research and development effort would produce, within the next five or ten years, a better excavation technology and improved boring system capable of reducing present costs drastically, with a resultant great saving. The time for this effort is now, but where the enabling money for this effort will come from, I have no idea. Machine builders should be encouraged to design and develop a shield- type boring machine capable of continuous mining through varying types of ground or rock by incorporating the possibility of making minor modifications such as change of bit type, power package, etc. Such a machine could

Jan 1, 1970

By R. Maddin, N. Ujiiye

ALTHOUGH the cold-rolled texture for body-centered-cubic metals and alloys is well known (see, e.g., Barrett'), the pole figure representing the texture may be interpreted in two ways. It may be regarded as consisting of several ideal preferred orientations with an associated spread (a view which is shared among several investigators2), or it may be regarded as consisting of two sets of continuous preferred orientation also with an associated spread."." Recently, Chen and Maddin7 noted a stable (001) [loo] end orientation for molybdenum single crystals rolled at low rates of reduction provided the initial rolling. orientation" was close to the cube ori-

Jan 1, 1957

By J. Chipman, J. C. Fulton

Reduction of silicon from blast-furnace-type slags by carbon-saturated iron is a very slow reaction even under conditions of rapid stirring. Equilibrium under atmospheric pressure of carbon monoxide was approached from both sides, and the silica-silicon relation was established at temperatures of 1425º to 1700°C for slags containing up to 20 pct Al2O3. Silicon carbide is formed by reaction of graphite with high silica slags and the conditions for its formation were determined. Activities of SiO2 and of CaO in their binary solutions at 1600°C were determined. The effects on the activity of SiO2 were established for additions of 10 to 20 pct AI2O3 and of 10 pct MgO. STUDIES of chemical reactions between blast-*>-5 furnace slags and metal have been focussed on the transfer of sulphur from metal to slag. The important role which silica reduction plays in this process' has led to a study of the transfer of silicon from slag to metal and the equilibrium represented by the equation SiO2 (in slag) + 2C (graphite) = Si + 2CO (g). [I.] The authors2 have published an account of the experimental method employed in attacking this problem and of three series of experimental results at 1600°C. This paper contains data on some additional compositions and extends the observations to cover the temperature range 1425° to 1700°C. The data are used to determine the activity of silica in the slags. As in the earlier experiments, the atmosphere was carbon monoxide which flowed through the furnace at 150 ml per min. In certain heats designated in the tables and figures, the gas was bubbled through the melt using a graphite tube. The latter increased in porosity during a run and in some cases bubbling ceased as indicated by cessation of surging. Some results were discarded for this reason. Experimental Results The new data are shown in Tables I through V and both old and new data are plotted in Figs. 1

Jan 1, 1955

By L. C. Weiner

For zinc single crystals, xo = 3o, a surface coating raises both the cleavage and yield strengths over a large temperature range. The "brittle temperature," associated with slip after completion of twinning, does not coincide with the point of intersection of the flow and cleavage curves, which is associated with twinning. A surface film has no effect on the brittle temperature, while it lowers the intersection temperature some 20°. For crystals, yn = 83o, a coating decreases the cleavage strength, making it temperature independent, as well as increases the brittle temperature or its equivalent, the intersection temperature, 20°. These observations are described on the basis of a dislocation-pile-up-at-a-barrier model for brittle fracture; in crystals x,, = 3o the number and distribution of twins play a vital role. IN a recent investigation on the effects of solid environments on the brittle fracture of zinc single crystals,' it was demonstrated that the presence of a surface film changes the cleavage strength of these crystals, either increasing or decreasing it, depending on the crystal orientation. An increase in cleavage strength of some 43 per cent was found for coated crystals oriented x, — 3o K = 28",* while a decrease of 48 per cent was observed with crystals X" = y» — 83". Moreover, these effects were found

Jan 1, 1959

By David B. Scott

When mining operations were first instituted in the mines of the Miami Copper Co., at Miami, Ariz., the relatively hard character of the ground in the western section of the property made it seem advisable to use a wide shrinkage stope and pillar system. The system as finally evolved was applied to the mining of 2,300,000 tons of ore by the use of stopes and pillars each 50 ft. in width. Development, mining and extraction of this reserve has been continuously in progress since 1910, and the final stages of extraction are now reached. A complete survey of all phases of this system can therefore be made. Modification in working methods was obviously necessary, and the system to be described is believed to be typical of the best features. Development The preliminary work had three main objectives: The opening of a haulage level, the construction of a drawing-off level, and the driving of sublevels for use in stoping. In addition to these, some extra sublevel drifting was necessary to determine exactly the boundaries of the orebody, the general outline having been determined by churn drilling. This development was based on the requirements of stopes 50 ft. wide, with pillars 50 ft. wide between each stope. The length of these units varied from 200 to 500 ft.. Haulage Level The tramming level was 50 ft. below the floor of the stopes, and the tramming lines were run parallel with the long axis of the stopes. These lines were also beneath the middle of the stopes and pillars. Each line therefore served one stope or one pillar, this arrangement making it possible to load along an entire stope without switching or uncoupling. This advantage is apparent principally during the process of stoping when rapid drawing of excess broken ore is desirable. Furthermore, the arrangement of the drawing-off level chutes at 25-ft. intervals, as shown

Jan 1, 1917

By Joseph G. Debanné

Foreword The three case histories and the liquid fuels planning scenario presented in this paper span a twenty year period, from the pioneering days of computers in the petroleum producing industry during the mid-fifties, to the energy crisis era of the seventies. Inasmuch as two of the main actors, Ian McKinnon and I, are featured in all three case histories, while I am currently involved in the fossil fuels scenario, this paper provides four related and personal spot readings along an evolutionary path: from the one dimensional technical domain to the multi-dimensional techno-socio-economic domain of computer applications in the petroleum industry. Coincident with this evolution in the direction of increasingly comprehensive and powerful computer applications, the evolution in hardware/software capability and in analytical power are also kept in perspective. The three case histories are: 1. The Bonnie Glen-Wizard Lake Case (Calgary, Alberta, 1955-1957); 2. The TransCanada-Great Lakes Gas Transmission Case (Ottawa-Washington, 1966); 3. The Westcoast Transmission - El Paso Pipelines Gas Export/ Import Case (Ottawa-Vancouver-Washington, 1966-1967). The liquid fuels planning scenario is a demonstration exercise rather than a case history; however, it represents an important point on the evolutionary curve and, provides a concrete example of tech-

Jan 1, 1977

By William Fink

ALUMINUM forms not only binary compounds with most of the metallic elements but also forms many ternary or more complex constituents. Several of those occurring in the more important alloy systems have been identified under the microscope and the action of various etching reagents has, been carefully studied.' The determination of the structure and composition of these complex constituents is a matter of some difficulty and little information is available. X-ray crystal analysis offers a promising method for the study of such constituents. First, and of considerable importance, is the possibility of recognizing the presence of a given constituent by means more positive than microscopic observation. Evidence can also be obtained concerning the nature and composition of the constituent in question and ultimately it should be possible, at least in some cases, to describe the structure including the relative locations of the various atoms. In this paper some results of an uncompleted study of the constituents of the aluminum-iron-silicon system are given and the methods employed are described. Inasmuch as iron and silicon are the chief impurities in aluminum, the constitutional relations of this system are of fundamental importance in the metallurgy of pure aluminum and its alloys; the system has been studied by several investigators and the more important contributions have been reviewed recently.2 Fig. 1 shows the structure of the aluminum-rich alloys after prolonged annealing at 560° C., in accord with one of the most recent investigations.3 The ternary alloys examined in the course of the present investigation were all annealed at 550° or 560° C.; in fact, some of the specimens were the identical ones used by Dix and Heath, who kindly supplied them for this work. Since the results

Jan 1, 1930

NORTH AMERICA Number Members Alaska 43 Canada 340 Mexico 205 Newfoundland 4 United States Alabama 39 Arizona 120 Arkansas 11 California 699 Colorado 168 Connecticut 89 Delaware 18 District of Columbia 140 Florida 20 Georgia 6 Idaho 78 Illinois 214 Indiana 77 Iowa 12 Kansas 24 Kentucky 33

Jan 1, 1936

By George Kunz

(Butte Meeting, August, 1913.) THE manifold inconveniences resulting from the absence of a uniform standard of mass for determining the weight of precious stones have long been obvious. This lack has been keenly felt in commercial transactions, and those who have devoted time and research to the study of historic diamonds and precious stones have had frequent occasion to deplore the absence of such a standard in the past. In a paper read in Chicago in 1893, before the International Congress of Weights and Measures, held in connection with the World's Columbian Exposition, the writer suggested dividing the carat into 100 parts, and constituting a standard international carat of 200 mg. ; that is, 5 diamond carats or 20 pearl grains to a French gram, making 5,000 carats or 20,000 pearl grains to a kilogram. He also called attention to the fact that while this would depreciate the present diamond carat or pearl grain only about 2.5 per cent., it would abolish the troublesome discrepancies between the various carat-weights now in use, and could be easily explained and understood everywhere.1 The subject of the various diamond carats, their incongruity, and the resulting confusion as to the correct weights of historic gems when definite records of them are searched for, has been fully treated by me in an extensive study of this subject in The Book of the Pearl.2 To the earnest and unremitting efforts of C. E. Guillaume, Director of the Bureau Internationale des Poids et Mesures at Sèvres, is largely clue the eventual success of this eminently desirable reform, which lie has constantly urged both by articles on the subject and by addresses delivered in Paris before the International Committee for Weights and Measures.3

Jan 7, 1913