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By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By W. H. Newhouse

During the past few years the writer has been impressed by the close relation of many epigenetic orebodies with anticlinal structures. In the literature on ore deposits there is occasional mention that an oreshoot or district is on an anticline, but in most of the descriptions no weight or significance is attached to the relation, and usually the fact is concealed in a mass of structural detail. A few writers have stressed the relationship in a few districts or on a certain type of deposit. Church, Spurr, Butler, Stahl and Schuette have called attention to certain features, but the general extent of such a correlation has not been made known in any publication that the author has seen. A recent article1 on the localization of ore deposits, by well-known geologists, does not consider this common association. The author has seen in the field a number of the structural features described, and in addition has made a fairly complete review of the literature. This paper presents enough of the examples found to show the frequency of the relation to anticlines, and since only a few deposits on synclines are known, all of these of any importance of which the writer knows are mentioned. With certain qualifications which are discussed later, epigenetic ore deposits of replacement or vein type are mostly found where local upwarps of the earth's crust have taken place. Where formations antedating the ore deposits are present in the proper attitude to demonstrate vertical warping (i. e., more or less horizontal beds) the structural feature on which a mineral district, or mineralized area is located is almost always anticlinal, or domelike in nature. Some or even most of the ore deposits in a given district may be on the flanks of the upwarp, but few major districts are located definitely on downwarped areas. Synclinal basins within certain limits of size appear to be unfavorable to the type of fracturing that admits ore-bearing solutions. Replacement orebodies frequently are localized in small anticlines or domes, the size of the anticline or roll often being more or less commensurate with that of the enclosed oreshoot. This feature certainly ranks

Jan 1, 1931

By H. J. French

At the request of a committee of the Engineering Division,' National Research Council, a study of the properties of boiler plate at various temperatures up to about 900' F. (482" C.) has been instigated. The following is a report of preliminary tests made on two grades of 1/2-in. plate and includes a description of the apparatus used in the determination of the proportional limit. Detailed reference to- the many published investigations in connection with the properties of steel at various temperatures will be omitted from this report. Suffice to state that results obtained for variation in tensile strength, elongation, and reduction in area with temperature are in substantial agreement with the effects now generally considered to be correct. Comparison of proportional limit values with results obtained by other investigators will be found in the conclusions. Materials Used The steels tested were $1/2-in. (12.7 mm.) open-hearth boiler plate of firebox and marine grades. The specified tensile strength and the analysis for each are shown in Table 1. In the manufacture of this material, a

Jan 1, 1922

It is interesting to note that during the period that has elapsed since the Institute's formation, wood charcoal, anthracite and bituminous coal, as well as beehive and by-product coke, have been used as blast-furnace fuels, that the reign of supremacy of each fuel was associated with specific periods, and that each successive era was marked by a production of pig iron greater in quantity than the one it followed (Fig 1). The transition of the manufacture of blast-furnace iron from charcoal to anthracite and then to beehive coke, and ultimately to by-product coke, is a reflection of the economic limitations of each fuel coupled with availability sufficient to meet the increased demands of each succeeding decade. It is a pattern that has been followed almost without exception in the history of pig iron in every country. CHARCOAL Colonial production of iron relied exclusively on wood char- coal as a fuel, and the iron industry of this count recognizes the important role played by this fuel. Charcoal iron has been available to consumers since the beginning of the organized iron industry in America in 1645, by John Winthrop at Saugus, Mass.,1 and although its greatest use antedates the formation of the Institute, it is still used to some extent. Until about 1840 nearly all of the pig iron manufactured in the United States was made with charcoal, and it continued as a principal smelting fuel until 1855.2 After that time, more pig iron was produced with other fuels, despite the fact that

Jan 1, 1948

By H. J. French

At the request of a committee of the Engineering Division,' National Research Council, a study of the properties of boiler plate at various temperatures up to about 900' F. (482" C.) has been instigated. The following is a report of preliminary tests made on two grades of 1/2-in. plate and includes a description of the apparatus used in the determination of the proportional limit. Detailed reference to- the many published investigations in connection with the properties of steel at various temperatures will be omitted from this report. Suffice to state that results obtained for variation in tensile strength, elongation, and reduction in area with temperature are in substantial agreement with the effects now generally considered to be correct. Comparison of proportional limit values with results obtained by other investigators will be found in the conclusions. Materials Used The steels tested were $1/2-in. (12.7 mm.) open-hearth boiler plate of firebox and marine grades. The specified tensile strength and the analysis for each are shown in Table 1. In the manufacture of this material, a

Jan 1, 1922

By Alan Morris

The investigation of the hot-working properties of metals and alloys furnishes a problem which has been attacked in many ways. Tensile, impact and hardness tests on heated specimens have furnished interesting data, but in most cases either the tests are difficult to make or the results hard to translate into terms of practical value. Some investigators have used the drop hammer to advantage. It furnishes a rapid and simple method of comparing the plasticity of metals at elevated temperatures. The indications obtained by its use are of value only in so far as their significance is understood and they can be intelligently used to predict the behavior of a given metal under given hot-working conditions. The work reported here was undertaken not only to add something to the existing volume of such data but also to contribute to our understanding of the results. Doerinckel and Trockels1 used cylindrical specimens and determined the work required to reduce the specimen to one-half the original height. Ellis2 studied the effect of constitution on the malleability of steel at high temperature. His method and that of Kent3 were similar to the one used in the present work. The tests described by Kent were made on samples of tin, zinc, aluminum, copper, lead, 70:30 and 60:40 brasses, with and without a small quantity of lead. He concluded that the test would "indicate whether a material can be forged at a given temperature without cracking." This interpretation must be used with caution. While it is probably true within limits, one must consider the severity of the forging operation. Again, it will not apply strictly to forms of hot working other than forging. For instance, an alloy running 61.0 per cent. copper, 3.25 per cent. lead, remainder zinc, will crack badly in the test, yet, it is extruded commercially. When the possibility of hot-working a new alloy is being considered a study of its drop-hammer test should help

Jan 1, 1931

By Thomas M. Chance

All gravity methods for the separation of ore from gangue, or of slate and other refuse from coal, are based upon differences in the falling velocities, in some fluid medium such as air or water, of the materials to be separated. As all materials falling in a vacuum have the same velocity, independent of the size, shape, weight or specific gravity of their individual particles, it would be more accurate to describe the operation of these methods as depending upon the retardation of falling velocities effected by the resistance of a fluid medium, this retardation being greater for small or light particles than for large or heavy particles. This generalization is true also of those appliances utilizing centrifugal force to replace or to supplement the action of gravity. The separation of materials of different specific gravities by means of a fluid having a specific gravity greater than that of the lighter particles and less than that of the heavier particles has not been applied commercially, or on a large scale, to the separation of ores or to the washing of coal, the method being limited to laboratory experimental work or to laboratory determinations for the purpose of checking up the work of jigs, classifiers, and other types of concentrating appliances. A solution of zinc chloride has thus come into general use in the laboratory to separate coal, bony coal, and slate, both to check up the work of coal-washing plants and for the purpose of making tests preliminary to the designing of coal-washing plants. The use of a heavy solution of some chemical in water has often been proposed for making such separations, especially in connection with the washing or preparation of coal. Practically insuperable difficulties, however, have prevented the commercial development of any such process, the difficulties being both physical and financial. The cost of the chemical used to make high-gravity solutions is usually prohibitive, and the freeing of the coal from all traces of the chemical is found to be practically impossible. Such solutions inevitably penetrate the individual lumps and particles of coal, transfusing into the pores and saturating the joint-planes, and very large quantities of wash water

Jan 1, 1918

By J. M. Hodge

This paper represents a start on the problem of choosing alloy steels for a given application on the basis of toughness as indicated by the room temperature notched bar impact value at the desired hardness level, and as such, is very useful. I believe, however, that the authors will agree that it is only a start on this problem. The authors state that neglecting temper brittleness or other possible effects of the tempering temperature level, the impact values at a given grain size level will be determined principally by the hardenability. This is, of course, true inasmuch as the hardenability determines the microstructure, but it serves to emphasize the broad field that hardenability now covers, since this study apparently includes mi¬crostructures ranging from full martensite to coarse pearlite. Furthermore, the + or - 20 ft-lb spread in the correlation with hardenability, which certainly limits the usefulness of these results for many applications, indubitably reflects the wide range of microstructures corresponding to a given value of hardenability in terms of the difference between full martensite and asquenched hardness.

Jan 1, 1947

By F. W. Newhall

DURING the latter part of the year 1931, the Republic mine of the Republic Steel Corporation, at Republic, about 4 miles south of Browns-ville, Pa., was mining coal along four rib or fracture lines. One of these lines, the west butt rib line, was retreating towards a concrete-lined air shaft, 320 ft. deep, which had been sunk in 1911 for ventilation purposes. With the normal rate of mining at that time, it was expected that this rib line would pass the shaft in three or four months and the shaft would then be abandoned and allowed to cave. Realizing the opportunity presented for the study of an unusual case of ground movement, the question of conducting the study was presented by the junior author to the chairman of the Institute's committee on Ground Movement and Subsidence, Mr. George S. Rice, who presented the matter to Mr. G. H. Morse, General Manager of the Northern Mines, Republic Steel Corpora-tion, and he agreed to cooperate with the Bureau of Mines in making the study, the results of which are presented in this paper. Acknowledg-ments are due to Mr. Morse for his full cooperation in this work and to Mr. G. S. Rice and Mr. J. W. Paul, both of the U. S. Bureau of Mines, for their advice and guidance during the course of the work. The authors are indebted to Mr. B. F. Herbert, mining engineer, Northern Coal Mines, Republic Steel Corporation, who assisted in all the surveys, and Mr. W. H. Smith, draftsman, U. S. Bureau of Mines, who prepared all illustrations for publication.

Jan 1, 1934

By Arthur Phillips

The progress made in recent years in the art of dispersion-hardening has naturally led to an intensive study of alloy systems capable of yielding supersaturated solid solutions at ordinary temperatures. In general, the investigations have been confined to rather precise determinations of solubility limits and to experimental approaches designed to furnish more complete information regarding the rate and nature of precipitation under appropriate thermal conditions. Efforts are being made to focus more sharply on the atomic changes that are a direct consequence of the instability of the supersaturated solution. Here precision X-ray methods have come to be of considerable importance because lattice parameter measurements indicate very precisely the concentration of solute atoms in the solvent lattice. In spite of the general acceptance of parameter values as a criterion for the placing of solubility limits, it may be suggested that no thorough appraisal has been made of the several factors that conceivably may affect such measurements. More specifically, little attention has been devoted to the significance of surface energy conditions, specimen size and method of preparation, with particular regard to the genesis of the grains and the surface concentration changes as a consequence of heat treatment and etching. Stenzel and Weertsl recently published the results of a detailed study of precipitation reactions in aluminum-rich copper alloys. They found that, although copper lowers the lattice constant of aluminum, a 5 per cent copper alloy quenched from 150" and 225' C. had parameter values unquestionably higher than that of pure aluminum. Their results seem to substantiate, at least qualitatively, the earlier work of von Göler and Sachs,2 who indicated a parameter value, for the same alloy annealed for 24 hr. at 200° C., some 0.0008Å. larger than that of pure aluminum. Stenzel and Weerts attributed the abnormal lattice dimension to the effect of strain induced by the precipitation of CuA12. Weerts3 later

Jan 1, 1934

By Howard Scott

INVAR is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100° C. and soon reaches the value of copper. Guillaume1 met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detri-mental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By William E. Ford, Edward Salisbury Dana

A. Hexagonal Division 1. Normal Class (13) Beryl Type 2. Hemimorphic Class (14) Zincite Type 3. Pyramidal Class (15) Apatite Type 4. Pyramidal-Hemimorphic Class (16) Nephelite Type 5. Trapezohedral Class (17) B. Trigonal or Rhombohedral Division 1. Trigonal Class (18) Benitoite Type 2. Rhombohedral Class (19) Calcite Type 3. Rhombohedral-Hemimorphic Class (20) Tourmaline Type 4. Trirhombohedral Class (21) Phenacite Type 5. Trapezohedral Class (22) Quartz Type 6. Other Classes (23) 7. Other Classes (24) Mathematical Relations of the Hexagonal System 119. The HEXAGONAL SYSTEM includes all the forms which are referred to four axes, three equal horizontal axes in a common plane intersecting at angles of 60") and a fourth, vertical axis, at right angles to them. Two sections are here included, each embracing a number of distinct classes related among themselves. They are called the Hexagonal Division and the Trigonal (or Rhombohedral) Division. The symmetry of the former, about the vertical axis, belongs to the hexagonal type, that of the latter to the trigonal type. Miller (1852) referred all the forms of the hexagonal system to three equal axes parallel to the faces of the fundamental rhombohedron, and hence intersecting at equal angles, not 90". This method (further explained in Art. 169) had the disadvantage of failing to bring out the relationship between the normal hexagonal and tetragonal types, both characterized by a principal axis of symmetry, which (on the system adopted in this book) is the vertical crystallo raphic axis. It further gave different symbols to faces which are crystallographally identical. It is more natural to employ the three rhombohedra1 axes for tri- gonal forms only, as done by Groth (1905), who includes these groups in a Trigonal Syslem; but this also has some disadvantages. The indices commonly used in describing hexagonal forms are known as the Miller-Bravais indices, since the were adopted by Bravais for use with the four axes from the scheme used by Miller in the other crystal systems.

Jan 1, 1922

By S. A. Falconer

Much attention and publicity has been given, during recent years, to grinding, classification, flotation, and thickening. The various technical papers, and symposiums held to discuss these important phases of milling, have contributed to a better understanding of the fundamental principles and operating variables involved. Another important part of milling— to the flotation operator—is a treatment step to which frequently too little attention is given—"conditioning," or the treatment the ground mineral pulp receives before it enters the flotation machines. "Conditioning" is a hackneyed and frequently misused term, commonly employed to describe the pretreatment of surfaces of minerals in ore pulps or mill products prior to froth flotation. In general, such pretreatment is for the purpose of changing the flotation characteristics of these mineral sur- faces to enable them to respond in some desired predetermined manner when subjected to flotation. Taggartl states that the function of conditioning is "either to insure selective collector coating of one mineral species while another species is not; or to take such steps as will compensate for departure therefrom." As 0. C. Ralston has stated? ... we are still faced with the fact that some mineral particles are water-avid, others air-avid, and that by properly modifying them they may be enhanced or diminished in desirable or undesirable avidity. Coatings on minerals must still be assumed to fall into three classes: (1) a coating of immiscible oil, (2) a layer of adsorbed substance, (3) a chemically produced coating. It is submitted that the process of preparing mineral surfaces for subsequent flotation treatment should take into consideration physical as well as chemical means for altering the normal flotation response of the mineral surfaces. A more descriptive word than "conditioning" is needed to designate broadly these procedures. The minerals in many ores cannot be made to respond in a normal manner to usual methods of "conditioning" with selectivity modifying reagents, until they have been cleansed, or interfering slimes and soluble salts have been removed from the ore. Therefore, it appears important to include under the general subject of "conditioning" a discussion of the purposes, methods used, and some of the advantages of these pretreatment steps. This is dealt with under the subject heading " Initial Treatment of Mineral Surfaces and Ore Pulps." Under this broader interpretation, the methods employed for treating mineral surfaces to alter their flotation characteristics may be divided into three general classes: 1. Physical methods.

Jan 1, 1950

By M. Cohen, W. J. Harris

The recent application of lineal analysislt2 to the austenite-martensite reaction has made possible a quantitative study of the kinetics of this transformation during rapid cooling. Martensite range curves can thus be constructed to portray the onset of the reaction at Ma and its subsequent progress as a function of temperature down to and below the ambient. It now seems in order to investigate other aspects of the martensite transformation, using this quantitative method of approach. One of the least understood characteristics of the austenite-martensite reaction is that of stabilization which has been defined by Troiano and Greninger3 as 'la lowering of Ma, resulting from aging, without change in chemical composition of the parent solid solution." In other words, if the hardening quench is arrested at a predetermined subcritical temperature (TA) for a sufficient period of time, more austenite may be retained at a given lower Or reference temperature (Tr) than if the steel had been cooled directly and rapidly to Tr in the first place. For the purposes of the work at hand, the extent of stabilization produced by the isothermal treatment at Th is measured explicitly in terms of the excess austenite (6) that exists in the steel at T,, over and above the amount that is normally present after direct quenching to T,. T, is conveniently taken to be room temperature, but this choice is not essential and is sometimes undesirable. The holding temperature (TA) may be above or below M,, and still cause stabilization depending upon the themistry of the austenite. stabilization has been found to occur in the presence of bainite4 and of martensite6,6,7,8 as well as in the absence of either,g The phe-nomenon of stabilization is not concerned with (and may even be obscured by) ferrite formation or any other type of phase change occurring at T~ that alters the chemistry of the remaining austenite. Such a structural change would obviously influence the martensite transformation during subscquent cooling. Stabilization, however, is more subtle; it appears to manifest itself without detectable variation of the austenite composition, whether in the presence or absence of transformation products. There are relatively few direct references to stabilization in the literature. The stabilizing effect of room temperature aging and tempering on the subzero transformation of retained austenite has been clearly shown in plain carbon,6,8 low alloy6s7.8 and high alloy tool steels.10'5 ssa- with the as-hardened steel, the degree of stabilization increases with tempering time and temperature through

Jan 1, 1949

By Philip B. Bucky

[CONTENTS t. How Does One Determine WhetherPAGE an ore Body Will Block-cave?R. W. Hughes13 Sherman R. Burdick 13 PAGER. T. Gallagher 14 Mark A. Smith 2 C. F. B. Price, Jr.14 Harry A. Leidich2Benjamin F. Tillson 14 McHenry Mosier2C. F. Jackson14,17 R. W. Hughes2R. Taborelli15 Sherman R. Burdick3Frank A. Ayer16 R. T. Gallagher 3Philip B. Bucky16 Benjamin F. Tillson 3Rollin Farminr6 Lucien Eaton 3J. L. G. Weysser15, 0,17 C. F. Jackson 3George S. Rice17 Philip B. Bucky32. How Does One Determine the Block4. What Determines the Procedure in Dimensions and the DevelopmentRemoving Caved Ore? Work Necessary to Make an OreHarry A. Leidich17 Body Cave?McHenry Mosier17,21 Mark A. Smith 5,7,() R. W. Hughes17 Harry A. Leidich6Sherman R. Burdick 18 McHenry Mosier6,7,12 R. T. Gallagher 18 R. W. Hughes6Mark A. Smith I8 Sherman R. Burdick 7Philip B. Bucky20, 21, 23 R. T. Gallagher 7C. F. B. Price, Jr20 Benjamin F. Tillson 7,11R. H. Bennett21 L. E. Young7C. F. Jackson 21, 23 Robert D. Hoffman8, 1 2Gerald Sherman 3 . 21 Gerald Sherman8Tell Ertl21 Philip B. Bucky10, 11, 12G. K. Foster 23 R. S. McClellan 12C. H. Shoemaker23 Tell Ertl 12 3. How Do the Forces Act and What Are5. What Are the Criteria for Determining the Stresses Developed in a Blockthe Efficiency of a Block-caving That Cause It to Block-cave?Operation? Mark A. Smith 12, ISHarry A. Leidich23 Harry A. Leidich13McHenry Mosier24 McHenry Mosier13R. W. Hughes24 Sherman R. Burdick 24 R. T. Gallagher 24]

Jan 1, 1942

By V. W. Aubel

AMONG the iron-bearing ores of the world, the titaniferous iron sands of New Zealand are probably the least known to American engineers. This is not surprising in view of the fact that. American ironmasters look with disfavor on any, even domestic ores, containing over 1 per cent. titanium. The possibilities of smelting titanium-bearing ores in the blast furnace are still undetermined, but the problem of their efficient reduction is becoming more important each year. There seems to be little inclination on the part of American furnace operators to tackle this problem, and they will no doubt continue to utilize the non-titanium ores at their command, leaving research and experiment to those countries not so fortunately endowed. New Zealand has, however, been intensely interested in her deposits of titanium,bearing iron sand, and during the last 50 years considerable English and New Zealand capital has been expended on this problem. The extent of the New Zealand iron-sand deposits is almost beyond measure. From Patea north to Manuka Heads, along almost the entire west coast of the, north island, these deposits exist. Wherever there is beach sand along this 300 mi. of coast line, the sand is iron bearing. It varies considerably in grade; but wherever the contour of the coast affords small bays and inlets, large dunes are found that are remarkably uniform in quality. Several of these large deposits, especially those at New Plymouth and Patea, are noted for their high iron content. The dune at New Plymouth runs between 55. and 60 per cent. of metallic iron; the panning action of the prevailing westerly winds and northwesterly currents has no doubt resulted in this concentration. Whatever the origin of this material may be, there is no doubt that deposition is going on continuously. At New Plymouth, a small artificial harbor, protected from the drifting sand by a large breakwall, has been dredged. Here sailing vessels have for years been loaded with iron sand for ballast by means of a crane and grab bucket operated from the wall of the breakwater. Thousands of tons of sand have been removed from this spot

Jan 9, 1919

By Charles Goodale

With notes on other mines of the Marysville district by WALTER McDERMOTT, London, England, and F. L. Sizer, Dos Cabezas, Ariz. (Salt Lake Meeting, August, 1914) THE purpose of this paper is to review the history of the Drumlummon, one of the famous old mines of the West. Mining engineers, when sent to examine new mines in old districts, or to decide whether an old property, under new conditions, will pay to re-open, have had difficulty in learning anything authentic regarding workings which are under water, and historical facts about the working character of the ore, the total production, and the value of the ore with increasing depth. Not many years elapse after the pumps are pulled, before maps, books and records are destroyed, and the value of the publications of the Institute would be increased if they contained the history of many old mines now abandoned. The unsuccessful efforts of the writer quite recently in trying to obtain reliable information about a gold mine which was reported to have produced several million dollars between 1880 and 1888, the workings of which are now partially caved and under water, impressed upon his mind the desirability of having a permanent record of old properties. In this particular case, the owners insisted that under present conditions of improved methods of treatment -particularly by the use of cyanide, which was not an applied process when the mine was operated, the property. could be made to pay a handsome profit on ore left in sight in the old workings, but no assay records could be found to confirm these assurances, and even the records of bullion shipments had been destroyed. If surveys and maps were made as the work progressed, no trace of them could be found, and therefore opening of the ground through a new shaft and drifts therefrom would be attended by some risk while exploring near the old workings. Fatal accidents by flooding under these conditions have occurred, and as an evidence that miners have fears of such dangers, it was urged upon the Mining Committee during a recent session of the Montana Legislature, by a delegation of

Jan 8, 1914

By Warren J. Jackson, John L. P. Campbell

Automatic recording of the radioactivity of the earth's formations provides a log of relative intensities that, if properly interpreted, can be applied to oil-field engineering. Production, engineering, and geological departments regard the radioactivity log as a forward step in the securing of more conclusive information for successful well completions. Explanations of the technique, together with some of the problems to which radioactivity logging have been applied, are presented in this paper. Introduction Those responsible for the completion of new oil and gas wells, or with planning workover operations on old wells, have followed closely the development of radioactivity well logging because they are interested in reducing the number of unknowns that usually are present in such work. Many operators have made use of the log, or are acquainted with at least one of the applications, but it is unlikely that any one operator is familiar with all of the many applications that are possible. The purpose of this paper is to present a representative example of each of the many applications, wherever the information has been released by an operator, and to illustrate by hypothetical examples other applications, releases for which have not been given. In this way, it is hoped that a better understanding of the scope of this new engineering tool may be obtained. Athough the literature contains many references that describe in detail the theory, development, and application of radioactivity well logging, a brief discussion of the technique may be helpful to those who are investigating the subject for the first time, All rocks contain radioactive material in varying concentrations. In general, shales contain relatively more radioactive material than sandstones or limestones. These radioactive materials disintegrate with time into other materials of lower atomic weight, and in that process of disintegration the rocks are emitting many rays, the most penetrating of which is the gamma ray. The intensity of emission of the gamma ray is proportional to the quantities of radioactive materials present. A higher rate of emission would be observed, therefore, opposite a shale than opposite a sandstone or limestone. Since measurable intensities of gamma rays are capable of penetrating as many as five concentric strings of casing, and as the gamma-ray intensity is relative to the formations, the measurements of variations in gamma-ray intensities offer a means of identifying cased-off formations in their proper stratigraphic sequence. TEe Gamma-ray Curve The measurement of gamma-ray intensi ties is accomplished by means of an ioniza-tion chamber that consists of a heavy cylinder, about 3 ft. long, that contains two insulated electrodes and is Med with an inert gas under high pressure. Under normal conditions no current will flow through the gas when an electrical potential is set up between the electrodes, but when

Jan 1, 1946

By John L. P. Campbell, Warren J. Jackson

Automatic recording of the radioactivity of the earth's formations provides a log of relative intensities that, if properly interpreted, can be applied to oil-field engineering. Production, engineering, and geological departments regard the radioactivity log as a forward step in the securing of more conclusive information for successful well completions. Explanations of the technique, together with some of the problems to which radioactivity logging have been applied, are presented in this paper. Introduction Those responsible for the completion of new oil and gas wells, or with planning workover operations on old wells, have followed closely the development of radioactivity well logging because they are interested in reducing the number of unknowns that usually are present in such work. Many operators have made use of the log, or are acquainted with at least one of the applications, but it is unlikely that any one operator is familiar with all of the many applications that are possible. The purpose of this paper is to present a representative example of each of the many applications, wherever the information has been released by an operator, and to illustrate by hypothetical examples other applications, releases for which have not been given. In this way, it is hoped that a better understanding of the scope of this new engineering tool may be obtained. Athough the literature contains many references that describe in detail the theory, development, and application of radioactivity well logging, a brief discussion of the technique may be helpful to those who are investigating the subject for the first time, All rocks contain radioactive material in varying concentrations. In general, shales contain relatively more radioactive material than sandstones or limestones. These radioactive materials disintegrate with time into other materials of lower atomic weight, and in that process of disintegration the rocks are emitting many rays, the most penetrating of which is the gamma ray. The intensity of emission of the gamma ray is proportional to the quantities of radioactive materials present. A higher rate of emission would be observed, therefore, opposite a shale than opposite a sandstone or limestone. Since measurable intensities of gamma rays are capable of penetrating as many as five concentric strings of casing, and as the gamma-ray intensity is relative to the formations, the measurements of variations in gamma-ray intensities offer a means of identifying cased-off formations in their proper stratigraphic sequence. TEe Gamma-ray Curve The measurement of gamma-ray intensi ties is accomplished by means of an ioniza-tion chamber that consists of a heavy cylinder, about 3 ft. long, that contains two insulated electrodes and is Med with an inert gas under high pressure. Under normal conditions no current will flow through the gas when an electrical potential is set up between the electrodes, but when

Jan 1, 1946