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By Edward Saibel

THE various theories that have been advanced to explain or predict the conditions under which a metal fractures may be divided into two categories: First, there are the macroscopic theories generally used in engineering practice. These are empirical in nature and limited in application. For example, the maximum normal stress criterion, which is quite satisfactory for a mild steel in simple tension at atmospheric pressure, no longer suffices when this steel is pulled under hydrostatic pressure.2 In all of these empirical theories, the critical condition characteristic of the material and of the loading conditions must be obtained experimentally. Secondly, there are the theories based on interatomic forces,3,4 or on the energy required to form new surface.5,6 These have all dealt with the theoretical evaluation of the tensile stress necessary to bring about rupture in a purely brittle manner; that is, without plastic flow preceding fracture. All of these attempts have led to values of the tensile strength of crystals or of polycrystalline bodies that are 100 to 1000 times higher than observed values. On this account, it has been thought necessary by some investigators to conceive of a microcrack structure or distribution of flaws throughout the specimen such that the resulting stress concentrations provide the factor necessary to bring about agreement between calculation and experiment. It has been pointed out by several observers7 that this point of view is highly unrealistic, in that the weakening effect of these flaws or microstructures must be very uniform from specimen to specimen, since the fracture stresses found for various specimens of the same material tested under similar conditions are so - nearly constant. Furthermore, since calculations based on atomic forces or atomic energy are for purely brittle fracture, a condition probably never satisfied in tests, agreement is hardly to be expected. Thermodynamic Theory Of Fürth In order to resolve this apparent discrepancy between the theoretical cohesive strengths and the observed fracture strengths, Fürth8 advanced a thermo- dynamic theory of the tensile strength of isotropic bodies based on work of Born9 relating to the melting of crystals. Assuming an isotropic material free from imperfections and flaws, behaving elastically up to the breaking point, and assuming a connection between rupture and the melt- ing phenomenon, Fürth obtains an expression for the rupture stress u, in the form [ ] where Q is the melting energy per unit mass, ? is the density, and µ is Poissons’ ratio. Fürth compares fracture stresses computed from Eq I with the fracture stresses of metals as given in the Landolt-Bernstein Tables (1927) and in the Hand-

Jan 1, 1947

By William Klement

KNELLER' has recently reported that extensive metastable solid solutions may be obtained in Cu-Fe alloys by simultaneous vapor deposition. This note reports that solid solutions, apparently single -phase, can be obtained for Cu-Fe alloys containing 0 to 20 and 85 to 100 at. pct Fe by rapid quenching from the melt; the inability to extend the solid solubilities further is related to the liquid miscibility gap, Fig. 1, as for Cu-Co alloys.2'3 Accurate lattice spacings of the copper-rich fcc and iron-rich bcc solid solutions have been obtained. Homogeneous alloys were prepared by casting4'5 and sintering2 from elements of 99.9+ pct purity. The quenching techniques were as before,' except the iron-rich alloys were liberally covered with argon while at elevated temperatures. Flakes about 1 sq mm in area were obtained and investigated with the Debye-Scherrer technique, as previously described.2,4 All X-ray work was done at 25° 2°C using filtered copper and cobalt K radiation. Relative visual intensities of the diffraction lines for the phases in the quenched alloys are shown in Table I. The lattice spacings of the fcc structure for alloys containing up to 80 at. pct Fe are plotted in Fig. 2. The variation of these lattice parameters with composition is in good agreement with the re- of cementite spots usually present (all hkl reflections are allowed) and the ease of confusing them with ferrite or martensite reflections. Copies of the report can be obtained by writing to the Materials Research Department, Rocketdyne. 6633 Canoga Avenue, Canoga Park, Calif., 91304. A copy is also available at the Engineering Societies Library, 2nd floor, 345 East 47th Street, New York, N.Y., 10017. Photocopies, either full-size or microfilm, may be purchased from the Engineering Societies Library. sults6 of Andersen and Kingsbury, Fig. 2, although there is some disagreement in absolute value. This discrepancy may be due to the different temperatures at which the X-ray measurements were carried out and perhaps to the different extrapolation procedures. Also, Andersen and Kingsbury6 state that their lattice spacings were computed relative to the wavelengths given by Siegbahn in 1933; this reference has not been found and it is assumed that the well-known 1931 wavelengths were used, the lattice spacings then being in kx units which are converted into angstroms by the factor 1.00202. There is no support for the contention that solution of iron decreases the lattice parameter of copper, as con-

Jan 1, 1965

By W. A. Schaeffer, Sidney A. Justin, Jr. H. D. Easton

Restriction and proration of petroleum production have increased materially the difficulties attendant upon the estimation of reserves, particularly in large, "flush" fields. Such practices preclude the use of decline or other curves, from which, under capacity production conditions formerly prevalent, much could be learned as to the ultimate recovery to be expected from a given field or lcase therein. In restricted fields that would produce at many times the low rate allowed by the regulations in force if allowed to flow without restraint, one is forced to use other information than production performance to predict the volume of oil recoverable. Examples are: at Kettleman Hills, California; the Conroc, Van and East Texas fields, Texas; the Iowa field, Louisiana. It is beyond the scope of this paper to apply a definite method to the determination of the reserves in any actual field, therefore the discussion will be limited to a consideration of available methods and an enumeration of important factors governing the accuracy of such estimates. The problem is to determine not only oil in place but recoverable oil in place, for a given field or tract, which is complex and depends not only on the characteristics of the reservoir but also on the plan of development, the production allocation scheme, the rate of production and many other factors. Many data must necessarily be considered, weighed as to inportance, and assigned quantitative values. Estimates of recovery in prorated fields have been discussed by Brace', Shaw2, Snider3 and others. The wide difference in estimates of ultimate recovery from a number of important recently developed fields demonstrates the inadequacy of

Jan 1, 1935

By AIME AIME

THERE is a constant reiteration in some quarters that technical societies are autocratic and that democracy is utterly lacking and that members would welcome democratic societies in which they had full, control of affairs. While we may not speak for other societies, than our own, in so far as th's Institute is concerned such charges- can only come from people uninformed as to the circumstances. It. is no curtailment of the democratic privileges of the members that a -slate is prepared by the Nominating Committee to be voted on at the annual meeting. The Constitution of the, institute stipulates how the nominating committee shall; be chosen and who shall compose it, which prevents anything like- a- clique controlling- the situation. The Constitution further provides how the nominees shall be distributed geographically and the by-laws specify geographical boundaries: for-these nomination districts. Further more, any man or complete ticket can be placed in nomination by means of a petition signed-by only; twenty-five members,- and three or four times such an independent slate has been so nominated and elected.

Jan 1, 1920

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

ROBERT WOOLSTON HUNT, who joined the Institute in 1874, served twice as its President, was made Honorary member in 1919, in whose honor the Hunt prize and medal were established, and who, within a month, had received the Washington Award, died at his home in Chicago on July 11, 1923. Robert Woolston Hunt was born Dec. 9, 1838, in Fallsington, Buck County, Pa., His father, Dr. Robert A. Hunt, of Trenton, N. J., graduated from Princeton College in the class of 1824, and later from the Uni-versity of Pennsylvania. His mother was Martha Lancaster Woolston. Mr. Hunt spent several years learning the practical side of iron making in the roll-ing mills of John Burnish & Co. at Pottsville, Pa. Later he took a course in analytical chemistry in the laboratory of Booth, Gar-rett & Blair, upon the completion of which he entered the employ of the Cambria Iron Co. at Johns-town, and for them, on Aug. 1, 1860, established the first laboratory in Amer-ica forming an integral part of an iron or steel organization. In the fall of 1861 he en-tered the United States military service, and was in command of Camp Curtin at Harrisburg, serving as mustering officer for the State of Pennsylvania, with the rank of Captain. In 1864 he assisted in recruiting Lambert's Independent Mounted Company, and was mustered into active ser-vice as a sergeant, having tossed up with a friend who had also participated in recruiting the company, as to which one should receive a Lieutenant's commission. Upon being mustered out of service, Mr. Hunt returned to the employ of the Cambria Iron Co. which sent him to the works at Wyandotte, Mich., where experiments with the new Bessemer process of making steel were being conducted. He was placed in charge of those works in July, 1865, and so continued until May, 1866, when the Cambria company called him back to Johnstown to take charge of their steel business, intending at once to begin the erection of a Bessemer steel plant. The plant, however, was not built for several years, and in the meantime the Cambria company began the rolling of steel rails for the Pennsylvania Railroad, using ingots of Bessemer steel produced by the Pennsylvania Steel Co. at their Steelton works. Mr. Hunt had charge of the steel for these operations; and in August, 1867, the first steel rails made in America on a commercial order were rolled.

Jan 8, 1923

By Theron Wasson

During 1936 the state of Michigan produced 11,868,573 bbl. This is approximately 4,000,000 bbl. less than produced in 1935. The principle reason for the decrease in production over the previous year was the rapid decline of the Crystal field, which reached its peak in October 1935. The old producing area—Mt. Pleasant, Porter, Yost-Clark— accounted for over 7,000,000 bbl. during 1936. Crystal produced a total of 2,400,000. Outstanding among the old fields were Vernon and

Jan 1, 1937

By C. B. Murray

"OUR experience from time immemorial has been that the furnace sampler and analyst usually find one or two, and sometimes more, points less iron than the Lake Superior shippers, but, fortunately, their contracts are `iron bound'; and, generally speaking, analyses at this end are practically useless, for we are obliged to settle on basis figured out to a half dozen decimals, and, as a rule, without recourse in the event of flagrant discrepancies between the two analysts." The above is an extract from a letter received by the writer of this paper from the President of an iron company, discussing the question of sampling. It so well expresses the opinion of many blast-furnace owners and managers that it seems a suitable text for a discussion concerning the need of uniform methods of sampling. If all railroad cars were loaded the same, if all stock piles were the same shape, and if ore was received regularly each day, the problem of sampling would be comparatively simple. The conditions, however, vary widely at different places, and at the same place from day to day, and it is probably impossible to determine upon any one method of sampling which will apply at all times and in all cases. However, it would seem as though some general principles might be suggested which would tend to overcome these wide differences in samples of the same thing. The sampling of a cargo of iron ore begins at the breast of ore in the mine. The ore is sampled from the mine cars, from the stock piles, and from the railroad cars at the mines. At the lower Lake ports the ore is practically all sampled from the boat, occasionally from railroad cars. At the furnaces, the ore is nearly all sampled from railroad cars and occasionally from stock piles.

Jan 1, 1914

By Joseph M. Jacisin

Fatigue tests were conducted on 2017-T4 alumium in alloy in an u1lrcthig.h vacuum of 2 x 10-lo Torr and in air. The vatio of vacuum-to-air faligue life for this ~malerial varied Jrom 3.5:1 at a strain of 2.5 X 1O-3 ill. pegr in. to 8:l at a strum of 3.3 x X ill. per 171. Sotlze pvelivtlinary data were also obtained on the faligue life of the alumirnum alloy in a dvy-nitrogen atmosphere. A dark deposit observed on the fracture surfaces of the aiv-tested specimens was identified as oxides of tr~angarzese and magnesium This observalion, and the close correlalion betaveen results obtained in vaCuum and dry-nitrogen environtments, tend to confirm that air stvongly influences the fatigue mechanism by a covrosion process. THE fatigue life of certain metals is known to increase when the atmospheric pressure is reduced. Gough and Sopwith1-2 postulated that this is due to a joint chemical and mechanical process operating in air at the surface of the metal with oxygen and water vapor playing significant roles. Wadsworth and Hutchings3 observed that aluminum is mainly affected by the presence of water vapor. Very little information is available on the fatigue properties of structural aluminum alloys in a vacuum environment. This report describes work performed on 2017-T4 aluminum alloy in an ultrahigh vacuum (2 x 10-loTorr) and in air. Some preliminary data are also presented on the fatigue life of the alloy in a dry-nitrogen environment. 1) EXPERIMENT 1.1) Test Material. The material tested was commerciaT 2017-T4 aluminum alloy which, in addition to aluminum, has an approximate composition of 4 pct Cu, 1 pct Fe, 0.8 pct Si, 0.5 pct Mg, 0.5 pct Mn, plus smaller amounts of other elements.* Some typical naturally age to a substantially stable condition. Specimens were then machined from these rods and ground to a No. 8 microfinish. In order to minimize variation in material characteristics, specimens were made from rods procured from the same lot. 1.2) Apparatus. The apparatus and test specimen used in the fatigue tests are shown in Fig. 1. The device utilized a single-cantilever beam with rotating-bending loading. Bending stress was applied to the fatigue test specimen by placing a spacer beneath the bearing support, thereby providing a constant deflec-

Jan 1, 1968

By Charles E. Lees

The Globe Mining District is in the southeast central part of Arizona, in Gila County. Globe, with a population of about 7000, is the terminus of the Arizona Eastern R.R., a branch line 130 miles long that connects with the Southern Pacific R.R. at Bowie. In 1874, prospectors crossing the Pinal Mountains from the west located what is generally known as the Old Dominion mine. For several years, it attracted little attention, because of the greater interest aroused by the discovery of high-grade silver ores in some of the foothills northeast of Globe. About six years later, the prospector turned his attention to the abundant copper ore revealed by surface workings along the Old Dominion vein, and, in 1884, the Old Dominion company erected two 30-ton furnaces. From 1888 to 1893, the Old Dominion company is said to have maintained an average annual production of about 8,000,000 Ib. of copper. Until Dec. 1, 1898, all supplies had to be freighted into Globe by wagons and the mines of the district operated intermittently because of high expenses, but with the advent of the railroad the Old Dominion company continued to be a large and steady producer. In the Globe district, the production of copper far exceeds in importance that of any other metal. There are four operating companies along the Old Dominion vein and the total annual product of these properties for 1923 was about 45,000,000 lb. of copper. The unit size of the mineral tracts in the district is the regulation mining claim, 600 ft. wide by 1500 ft. long, and all ownerships are held in fee. Globe is 3600 ft. above sea level, and lies between the Apache MOUntains to the east and the Pinal Mountains to the west. The principal drainage of the district is northward through Pinal creek into the Salt River. The general slope from the high point along the vein, where the Superior & Boston mine is, to Pinal creek, where the Old Dominion mines are, is about 250 ft. to the mile. Geology The oldest rocks in the district are pre-Cambrian crystalline schists known as the Pinal schist, which are the basement upon which all the later rocks were deposited. These latter rocks comprise shale, con-

Jan 1, 1925

By R. W. Raymond

The immense commercial value of the Gayley dry-blast process has been established beyond controversy. The testimony of practical blast-furnace managers, on both sides of the Atlantic, agrees that it reduces the cost of pig-iron about $1 per ton; but from the same testimony it appears that this direct economy does not by any means cover its commercial advantages—in fact, that under conditions frequently encountered in practice, it presents other benefits of even greater immediate financial importance. To this point I shall recur in a later part of the present paper. The history of the reception given to this invention, especially on the other side of the Atlantic, has repeated an experience familiar to American engineers. First, the reports of our practice were rejected as theoretically impossible, according to generally accepted notions and formulas; then the figures were reluctantly accepted; and finally the attempt has been made to explain how they could have been obtained. As to the Gayley dry blast, me Americans have been for several years in the last stage of the discussion, and the rest of the professional world is rapidly coming to it. Meanwhile, the remark has been repeatedly made that, whatever Mr. Gayley's process may turn out to be worth, it was not an invention on his part, but simply the energetic and persevering execution of a procedure already proposed by others. This question I wish to discuss first in the present paper. I. What Did Mr. Gayley Invent? Realizing that this is not the place for detailed argument on an issue of patent law, I shall not undertake to quote and criticise the publications prior to Mr. Gayley'a first patents. It may be admitted, without such critical analysis, that the possible advantages of removing moisture from the air forced into an iron blast-furnace were recognized and talked about a hun-

Jan 1, 1909

By Earl Oliver

IN times like these, the A. I. M. E. and similar societies have their greatest usefulness. . . . Individuals and companies acting alone in the development of public opinion are merely voices crying in the wilderness. United and organized they make a great force that can and does influence public action. . . . What part, if any, then, shall the A. I. M. E. take in these great stabilization processes of civilization? Shall it help to give direction and force to scientific knowledge which comes within its field of activity or shall it merely develop more of it? . . . Is it the A. I. M. E.'s function to help bring system, order and direction out of this situation so that the world can again have forward economic movement, or should it rest on its oars until other agenciess develop that public understanding and direction so necessary for economic progress? As we understand the functions of the A. I. M. E. Petro¬leum Division, they are to discover and promote knowl¬edge for the benefit of society on the mining of oil and gas. To the individual member of the Petroleum Division, there are certain advantages of social and professional contacts, but the collective purpose is that described. And the individual is benefited by membership only as the Division measures up to the purposes of its existence. Consequently, the welfare of this Division and that of its members depends on the extent to which it keeps pace with the needs of society on matters relating to the mining of oil and gas.

Jan 1, 1932

By C. C. Harris

The Gaudin-Meloyl equation for the size distribution of fragments resulting from single fracture is where y is the mass fraction of material smaller than size x, and x, and r are parameters to be determined from the experimental data. In physical terms, r is associated with the number of active flaws in a particle of characteristic dimension xo . The special attribute of this equation is its emphasis on the coarse size region of a distribution. There are various procedures2-5 for obtaining the parameters in Eq. 1, but a simple graphical method is awaited. This situation contrasts sharply with that in the cases of the familiar Gates-Gaudin-Schuhmann and Rosin-Rammler equations.6 The purpose of this note is to present a method based on a procedure7 which has been successful in several other applications.8-13

Jan 1, 1967

By R. S. McClellan

DURING the last year or so, with higher prices for gold and silver, many old properties in the West have come back to life. Almost every profitable producer in the old days has been considered, and the reasons for its shut-down investigated. If it seems likely that modern ore-finding, mining, and metallurgical methods, and S35 gold can again put the property on a profitable basis, someone can usually be found to back the venture. Methods of rejuvenation vary with the property, of course, but the following outline of what has been done with one group of mines in Idaho is fairly typical and may be suggestive to others. The Golden Chariot gold-silver properties, near Silver City, consist of seven old mines, working a vein system striking north and south, which had a productive length of some 3500 ft. The vein is a quartz-filled fissure with granite walls. Gold occurs in native, and with silver in the form of electrum which is the natural alloy of the two metals. Silver also occurs in a variety of sulfides. From 1064 to 1876, these old properties were worked intensively to an average depth of about 700 ft., through seven shafts which range in

Jan 1, 1934

By R. E. Reed-Hill, W. H. Hartt

The second order, {1011}-{1012} twin bands observed in critically deformed magnesium are often accompanied by an unusual form of kinking. These kinks, which lie adjacent to and run more or less parallel to the twin band habit, allow plastic deformation that occurs inside the twins to be accommodated into the matrix. The bend planes of these kinks cannot be explained using slip dislocations with Burgers vectors lying in the basal plane. A mechanism involving a single set of {1012)(1011) dislocations is proposed to account for the kink band habit, in good agreement with the experimental observations. It has been shown that second order, {101l)-{1012} twinning is an important phenomenon for magnesium deformed in the ambient temperature range. A detailed study of these twins has recently led to a better understanding of their irrational habit plane1 and their relation to fracture in magnesium.' This paper is concerned with a third aspect of these twins; this being the kink bands, originally referred to as shear accommodation kinks,3'4 that are often induced in the adjacent matrix. A twin band and its shear accommodation kink usually appear as a single macroscopic deformation, as seen in Fig. 1. The complex nature of these deformed regions is easily revealed, however, with the aid of a suitable microscope. It has been proposed374 that the primary function of these kinks is to accommodate the nonhomogeneous deformation that normally occurs in the second order twins. The twins tend to form as small discrete lamellae lined up approximately one in front of the other.''' Very large plastic deformations varying in magnitude from one twin to the next, may occur inside these lamellae. The kinks serve both to pass this strain into the matrix and to accommodate strain variations between twins. Deformation within the kinks, subsequent to their formation, has also been observed;3,4 and it is thought that this contributes to the strain accommodation process. The bend planes of the kinks have a habit near that of the twin band itself, which lies about 56 deg from the matrix basal plane. This orientation does not bisect the angle formed between the basal plane to either side of the bend plane and therefore differs markedly from the kink structure usually observed in hcp metals.'-' The present paper reports the results of a study of shear accommodation kinks and proposes a possible solution to the problem of the orientation of the bend plane. EXPERIMENTAL PROCEDURE Rectangular cross-section tensile specimens with axes parallel to (1010) and faces to (1210) and (0001) were cut and acid machined from a high-purity magnesium single crystal. After straining on an Instron machine the specimens were examined by both optical and replica electron microscopy. The basic procedures have been previously reported."' EXPERIMENTAL RESULTS AND DISCUSSION Structure of Shear Accommodation Kinks. A typical, large (101l)-{1012) twin band with its associated shear accommodation kink is shown running diagonally from upper left to lower right in Fig. 1. In this optical micrograph the twin band, consisting of a row of small, highly deformed twin lamellae, is visible as a narrow dark band along the left hand edge of the structure in question. The kink lies to the right of the twins, is approximately three times as wide, and is lighter in contrast. The horizontal slip lines visible on the general specimen surface correspond to matrix basal slip and are parallel to the tensile axis. Note that on the right-hand side of the band these slip lines can be followed from the matrix into the kink. At the kink band boundary the slip lines suffer a clockwise rotation of about 25 deg. Rotations of this magnitude are not uncommon. When a surface such as that in Fig. 1 is given an etch1 making it sensitive to polarized light, it has been observed that the slip traces in the kink are parallel to the basal plane trace in this region. This is in excellent agreement with the assumption that these regions are indeed kinks. Fig. 2 is an electron micrograph of this same twin band and kink. Note that a row of small supplimation pits has formed

Jan 1, 1969

By Leonard H. Goldman, Harold E. Marr

The PGT uranium assay probe is a borehole tool developed by Princeton Gamma-Tech over the last several years. It has the ability to do an in-situ assay of uranium in the presence of any amount of disequilibrium. It has some advantages over coring including cost, speed of analysis, and accuracy. In this paper we would like to give a brief description of the measurement and then show some sample logs from South Texas. Uranium exploration and development is carried out primarily by gamma logging since uranium daughters are prolific emitters of gamma rays. The conventional gross gamma tool for uranium logging is limited in value because of the inability of this tool to distinguish uranium from its daughters and other naturally occurring radioisotopes, such as potassium and thorium. This problem becomes severe in cases of disequilibrium. Disequilibrium, in a geological context, is defined as the condition when the gamma radiations from the daughter products are being emitted in a location different from that of the parent uranium. In the decay chain of uranium almost all the gamma radiation emitted in the entire chain comes from the daughter product, bismuth-214. Bismuth-214 is separated from uranium by several long-lived isotopes that are chemically active and have different physical properties, often resulting in shifts in the location of bismuth- 214 relative to the parent uranium. In the United States orebodies exhibiting disequilibrium are a common occurrence and the use of a gross gamma log to delineate uranium orebodies can lead to errors. At present the solution to the disequilibrium problem is extensive coring followed by chemical analyses of the cores. There are several drawbacks in using this technique. First is the high cost of coring, the second is the fact that no results are available for days, or typically, weeks after the drilling is done. Thus for development work, coring and drilling must be done on a grid basis and many additional holes are cored to ensure that the entire orebody is mapped. Another disadvantage to cores is the fact that a small volume is sampled, the volume of the core itself. This leads to problems in the mapping out of the orebody when the ore de- posit is not very homogeneous. The PGT probe described in this paper is a new solution to the disequilibrium problem. Basically, the probe measures radiations that come almost directly from uranium itself. The first daughter of uranium, which is protactinium-234 (Pa-234), is only separated from uranium by a 24-day half-life and no disequilibrium problems build up in such a short time. The PGT probe measures the intensity of a one MeV gamma line emitted by Pa-234 and, using this information, calculates the concentration of uranium. The PGT probe is 24" in diameter and 12 feet long. The probe contains a microprocessor which passes the information to a larger minicomputer in the truck. All data is analyzed on site, and the results from a high speed printer are presented to the geologist. Data is also available on 9- track IBM compatible tape for further processing. The PGT probe output is linear with uranium concentration. The only correction factor is for borehole size, and that only becomes important in boreholes bigger than seven inches in diameter. Dead time is compensated in the probe itself and no problems have been encountered in ore zones up to several percent UjO8. In addition to the uranium assay, a conventional gross gamma log is plotted alongside. Grade thicknesses for zones above cutoff are calculated as well as disequilibrium factors. COMPARISONS During its commercial operation PGT logged a series of 18 holes that had been cored and assayed. All of the holes in this series were logged in normal operation by regular field operators. The time to log each hole was generally under an hour, and in typical operation a PGT logging truck will do between 7 and 8 holes a day. The results of the comparison of the PGT and the core assays are presented in a series of figures showing plots of the PGT assay, core analysis and gross gamma measurements. The first three figures show individual holes with the gross gamma plotted along with the core and the PGT assays. All three logs were from holes on the reduced side of a rollfront deposit in South Texas. In Figure 1 we see the two wings of the roll- front at 143 ft and 150 ft separated by a barren zone. The wings are well defined both by the PGT assay and the core. There is approximately a one foot shift which can be attributed to drilling errors. The gross gamma is showing a rather severe discrepancy, being considerably lower and not showing the barren zone. The grade thickness calcula-

Jan 1, 1980

By S. J. Kidder

The Mogollon mining district is in the southwestern part of New Mexico near the southern end of the Mogollon range, from which the district takes its name. The town of Mogollon is but 371/2 miles in an air line northeast of Clifton, Ariz. The air-line distance from Silver City is 521/2 miles and from Tyrone, 57 miles. Supplies are transported by motor truck from Silver City. The distance by road is 75 miles, half of which is an improved highway of modern construction. Transportation has always been a large item of expense in carrying on operations in the district. Valuable ore is said to have been discovered in the Mogollon Mountains as early as 1870 but the first regular prospecting was carried on in 1875, by James C. Cooney, a sergeant from Fort Bayard. His discovery of rich silver-copper ores in the region of Mineral Creek led to the establishment of the Camp of Cooney. Remote from any settlements where there was a semblance of law and order, and harassed by the Apaches, development was slow and nearly 10 years elapsed before the village of Mogollon was established on Silver Creek. Prospecting in this section of the district had disclosed the outcrops of several promising veins containing silver-gold ores. Among the early claims located were the Last Chance, Top and Confidence, on what has proved to be the most productive vcin in the district. To the end of 1922, the Last Chance and Top claims had produced approximately 600,000 tons of ore and nearly 200,000 tons had come from the Confidence group of claims. The total value of the ore produced from this vein alone has amounted to about $9,600,000 in silver and gold. The Fanney vein was developed later and during its most active period of production contributed more than half of the output of the district. Other important locations, though far less productive than the above, were the Maude S, Deep Down, the Deadwood and the Pacific.

Jan 1, 1925

By H. S. Geismer

There are three general methods available for obtaining commercial brown iron-ore: hand-screening; washing; and washing and concentrating. Hand-screening has produced a large tonnage of ore in the past, but is rapidly falling into disuse, except as a preliminary step, largely because modern furnace-practice requires all forcigii material to be separated from ores before they are deliv-

Jan 1, 1912

By William P. Roe, James F. Ellis, W. P. Fishel

This paper reports the distribution of sulphur between iron and titanium in Fe-Ti-S alloys and in Fe-Ti-C-S alloys. The compound TiS was found, which exists as a separate phase at temperatures below 1200°C. Titanium in steels reacts with sulphur in preference to carbon. THE general relationship between sulphides and oxides suggests that titanium should form a sulphide having properties similar to those of titanium oxide. Specifically, titanium should form a sulphide having a high melting point, indicating a stable compound of low solubility in iron. In order for titanium to function as a desulphurizer or sulphur-fixing agent, it must form a stable sulphide. In order for titanium to be useful in steels as a sulphur-fixing agent, it must react with sulphur in preference to carbon; and to prevent red shortness, the sulphide formed must have solubility characteristics such that grain-boundary precipitation of a low melting phase be prevented. The terms desulphurizer and sulphur-fixing agent when used in this paper mean that titanium effectively ties up the sulphur as a stable sulphide of titanium and prevents the formation of FeS. The partition of sulphur between iron and titanium was studied first in a series of Fe-Ti-S alloys with carbon absent, and then in similar alloys with carbon present. It has been established1 a that titanium forms in Fe-Ti-S alloys a sulphide of undetermined composition which can be identified microscopically, and that the titanium-sulphur compound does not respond to sulphur printing. It has been suggested" that titanium acts as a sulphur-fixing agent, although little proof has been given. A report% f The Advisory Committee on Metals and Minerals summarizes the existing knowledge concerning substitutes for manganese in steels. Distribution of Sulphur Between lron and Titanium with Carbon Absent The alloys for this investigation were made by -melting Armco iron, metallic titanium, and iron sulphide in alundum crucibles in an induction furnace. The titanium was added after the other ingredients had melted. In these alloys it is recognized that some TiO, is present, since the melts were made in the air and since no other deoxidizing agent was used; therefore, some of the titanium was not available for union with sulphur. Thirteen ingots were made. Ingots 2 to 8 were cast in baked-sand molds; ingots 12 and 13 were cast in metal molds; and ingot 9 was allowed to cool in the crucible in which it was melted. All ingots were annealed at 900°C for 3 hr and were cooled slowly in the furnace. Subsequent information indicates that this anneal had no effect upon the titanium sulphide particle size, since the sulphide does not go into solution at this temperature. The ingots as-cast were approximately 8 in. long and % in. diam. The compositions of the eight ingots and the results of the partition of sulphur are recorded in Table I. Total titanium and total sulphur were determined by standard gravimetric methods. Sulphur, as iron sulphide, was determined by the evolution method. Boiling HC1 (1:4) liberates the sulphur from iron sulphide, but leaves the titanium sulphide practically undecomposed. A complete separation of titanium sulphide and iron sulphide cannot be made by digesting these compounds in dilute HC1 since titanium sulphide was found to dissolve slowly. The amount of titanium sulphide decomposed will depend upon the time in contact with the acid and upon the particle size of the sulphide. The point

Jan 1, 1952