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By E. D. Gardner

IN 1947 the metal-mining industry . passed through a year of readjustment; catching up on development work has caused production to suffer. Skilled labor has been short in most mining districts, notwithstanding the highest wage rate paid in the history of the industry. The trend has continued toward increased mechanization and refinements in practices and methods to increase the tons produced per man-shift. Improvements in procedures, however, have not kept pace with rising labor rates; and, in general, labor costs per ton mined have steadily increased since the war years. Prices of base metals have been the highest in a generation, but most producing companies can afford to pay the high wages. Capital expenditures have been approved for improvements to increase the output per man, both to reduce unit labor costs and to increase output. Surveys indicate a continuing

Jan 1, 1948

By E. R. Macgregor, J. Halpern

The kinetics of the reduction of cupric salts in aqueous solution by molecular hydrogen to metallic copper are described. The rate of reduction appears to be homogeneously determined and shows a marked inverse dependence on the hydrogen-ion concentration. Precipitation of copper is more rapid and complete in sulfate than in per-chlorate solution. A mechanism is proposed which accounts for this behavior. IN recent years a number of important hydro-metallurgical processes have been developed in which metallic salts in aqueous solution are reduced by gaseous hydrogen, usually at elevated temperatures and pressures, and thereby precipitated either in metallic form (e.g. Ni, Co, Cu) or as an oxide or salt of lower valence (e.g. VO, and VA).1 ; In connection with applications such as these, most of which involve heterogeneously catalyzed reactions, recent demonstrations"-" that salts of certain metals, e.g., Cu", Ag' , Hg" , and Hg,+ can activate molecular hydrogen homogeneously and thus catalyze hydrogenation reactions in aqueous solution, are of considerable interest. For example, cupric salts catalyze the otherwise slow homogeneous reduction of dichromate and ceric salts by hydrogen, i.e. Cr,O; + 3HL. + 8H1 ? 2Cr'- -- 7H,O [1] 2Ce ' ! H.. ? 2Ce" | 2H . [2] In perchloric-acid solution, where Cu" is not appreciably complexed, the kinetics have been found" " to be of the form -d [H,] _- k,[HJ [CU"]' dt -LCu+' l+ (k ,/k,) [H] [3] where, K = 1x10"' exp [—26,600/RT] 1, mole-' min-' ... [4] and (k ,/k,) - 0.25 at 110°C. This kinetic behavior suggests that the reaction proceeds by a mechanism involving the following sequence of steps kt Cu" +H1CuH' 4-HA [51 k., CUH + CU" ? + 2Cu f H' [GI 6Cu'+ Cr,07 + 14H'+ 2Cr- (¦ 7H,O + 6Cu" ['i] fast The catalytic activities of the undissociated cupric-sulphate and cupric-acetate complexes are somewhat greater (by factors of 6.5 and 120, respectively) than that of the simple hydrated Cu" ion.'" These considerations suggest that, in contrast to the other hydrometallurgical hydrogenation reactions, referred to previously, reduction of cupric salts in aqueous solutions by molecular hydrogen, should proceed homogeneously, and in the absence of an extraneous catalyst. This has already been demonstrated" for acetate-buffered solutions where the product of the reaction is a precipitate of cuprous oxide (Cu,O). In the present paper, an investigation of the reduction of cupric salts in perchloric-acid and sulphuric-acid solutions, leading to the precipitation of metallic copper, is described. Some results for the sulphate system, which is of considerable hydrometallurgical interest, have been reported previously by Ipatieff",' " and by Schaufel-berger' but these do not give a quantitative account, of the kinetics and mechanism of the reaction. Experimental The reduction experiments were conducted in the 1-gal, titanium-lined autoclave described in connection with earlier related investigations," " and using a similar procedure. The solutions were made up by dissolving known amounts of CP grade Cu(ClO,), and HC10, (or CuSO, and HISO,) in dis-tilled water. While in the autoclave, the solution was stirred and maintained at a constant temperature (±loc) and under a constant partial pressure of hydrogen gas. It was ascertained that the agitation (provided by two 3-in., four-bladed stirrers, rotating at 900 rpm) was adequate so that at no time was the rate of reaction limited by solution of hydrogen. During each experiment, samples of the solution were withdrawn periodically, allowed to cool, and the concentration of copper remaining in solution was then determined electrolytically. Some Cu' is formed during the reaction, but undergoes disproportionation when the solution is cooled to room temperature. For purposes of kinetic calcula-

Jan 1, 1959

By H. M. Beatty, T. L. Joseph, Gust Bitsianes

SUCCESSFUL blast-furnace operation depends upon securing an optimum balance between a number of important variables. This balance will vary somewhat from furnace to furnace in the same plant and with raw materials available in different plants. It is difficult to isolate the effect of any one variable unless it has a rather pronounced effect upon the efficiency of operation. The physical properties of iron ore and coke are known to affect the process, yet it is difficult to set up any definite yardstick by which these differences can be appraised. In recent years, whenever practicable, operators have taken steps to obtain better control over the absolute size and uniformity of size of the ore and coke. The size and physical character of the stone, however, have received comparatively little attention, emphasis being placed upon chemical composition, fluxing efficiency, and action as a desulphurizing agent. Since the stone occupies only about 10 per cent of the volume of the stock column, its influence upon permeability is less than that of the ore and the coke. The large pieces now used have a tendency to roll to the center and thus increase the permeability of this part of the stock column. Smaller pieces would be more effective in promoting the permeability of denser portions of the stock. The size and physical properties of blast- furnace stone are important also for reasons best understood by considering the results obtained by the crushing and the sizing of iron ore. Crushing ore to about 2 in. at Provo, Utah, and to about I in. in Alabama produced material somewhat less permeable to gases, even though sized. In spite of some sacrifice in permeability, the efficiency of the process was improved by crushing and sizing the ore, as indicated by a substantial saving in fuel and increased output. This saving in fuel is due in large measure to more thorough reduction of ore in the upper part of the furnace and to a corresponding decrease in the amount of carbon consumed prematurely above the tuyeres by the reaction CO2 + C = 2CO ? 70,080 B.t.u. [I] The physical properties of stone, its size and rate of calcination are important because they influence the rate at which C02 is released and the completeness of calcination before reaching a level in the furnace where the temperature does not exceed 1050°C. (1920°F.). Briefly, carbon dioxide from the limestone or from the reduction of ore may cause premature com- bustion of carbon above the tuyeres. Assuming that 1000 lb. of limestone is used per ton of pig iron, about 435 lb. of C02 will be liberated during calcination of a good grade of stone. If all this CO2 from the stone were to oxidize carbon prematurely, about 120 lb. would be consumed above the tuyeres in a heat-absorbing reaction. The amount of carbon thus consumed when a

Jan 1, 1942

By K. A. Natarajan, S. C. Riemer, I. Iwasaki

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration (nitrogen, air, and oxygen) on ball wear was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. Marked ball grinding tests and electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen toward wear (corrosive wear) is relatively small, and abrasive wear appears to be significant. Rheological properties of the slurry appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1985

By Grafton Thrasher

For the proper discussion of this subject it is necessary to incorporate in this paper the substance of part of an article published by rite in Metallurgical and Chemical Engineering for January, 1915. CAST-IRON TEST PLUG, SHOWING LOW MOTTLED AND MOTTLED FRACTURES. Several years ago, while I was thief chemist for a malleable-iron company, it occurred to me that the mere regulation of silicon was not sufficient to produce the desired degree of chill. But only after repeatedly encountering this fact in befit open-hearth and air-furnace, as well as cupola metal, was I led to regard variation in the total carbon as the principal cause of disturbance; and I resolved to determine the total carbon as well as the sill on ill every heat, and by a carefully prepared test piece to gauge the approximate degree of chill. The test piece selected was a round plug, 2 in. in diameter and 12 in. long, cast on end

Jan 10, 1915

By Dogan E. Gücer

In the following note, with the help of a new parameter of strain hardening, the attention is drawn to the close relationship between the relative performances of steels under plastic range cycling and their strain hardening characteristics. If a cantilever beam of rectangular cross section is tested with the arrangement shown in Fig. 1 in reversed bending between constant deflection limits at the lever head, the longitudinal strain-deflection hysteresis shown in Fig. 2 is obtained. There is no lateral strain due to constraint at the rectangular test section.' If the absolute value of strain undergone between a maximum state of tension and maximum state of compression is called A, it will be seen that A decreases with cycling rapidly due to the strain hardening in the test section and the ensuing change in the bent beam profile. It will also be seen that A reaches an approximately stable value around 10th cycle. If we call the first cycle strain range, A,, and that of 10th cycle, A,,, then is an index of the strain hardening capacity at a particular deflection level. A plot of n vs ? is reproduced in Fig. 3 for two ASTM steels: A-302 and A-201. A-302 is a low alloy structural steel, A-201 a low-carbon steel. The specimens were first normalized at 1650°F for 75 min then grooved with a milling cutter; and the notches were ground to 50G finish. The final operation before testing was a stress relief at 1150°F for 75 min. The behavior of the two steels changes around ?1 = 0.8 pct or A,, = A, -n = 0.7. If these curves are compared with the endurance life curves given in Fig. 4, it will be seen that the relative performance of the two steels also change around A,, =. 0.70 pct. The steel with lower strain hardening capacity (7) at a certain strain level shows a longer endurance life, irrespective of their strength levels. Since the exponent governs strain hardening at lower strain levels than the Modulus, the relative values of both parameters also coincide with the change in n values and the relative performances of the two steels at different strain levels. These two observations indicate to the close relationship be-

Jan 1, 1962

By J. B. Clark

In 1933, R. paris1 published a phase diagram for the entire Mg-Ca-Zn system. He reported the existence of a ternary intermetallic phase, Mg5Zn5Ca2, which formed a quasi-binary with the magnesium solid solution. Since then, no extensive work has been reported on the system. Recently however, indications of the existence of a second ternary in-termetallic phase in equilibrium with the magnesium solid solution led to a reinvestigation of the solid phase equilibria involving the magnesium solid solution. The 335°C (635°F) isothermal section was chosen for study. Metallography and powder X-ray diffraction were selected as the best mutually corroborating methods for determining the solid phase constitution. Seventy-six alloys were prepared from singly sublimed (99.95 pct) magnesium, electrolytic (99.95 pct) zinc and USP calcium. The analyses of some of the alloys are shown in Fig. 1. The alloys were melted in a graphite crucible under a chloride flu and chill cast in a split graphite mold. Dif-fusion couples (see Fig. 2) were prepared by casting molten Mg-20 wt pct Zn alloy around a cylinder of Mg-30 wt pct Ca alloy. The alloy samples and the diffusion couples were sealed under argon in Pyrex vials and annealed in a furnace capable of controlling within 1/2°C of 335°C. At the conclusion of the anneal, the alloy samples were quenched in ice water and the diffusion couples were air cooled. Procedures standard for magnesium alloys were used for metallographic examination. Powder X-ray diffraction patterns were taken on a G. E. camera with a 14.32 cm dim using nickel-filtered copper radiation. The redetermined 335°C (635°) section of the Mg-Ca-Zn phase diagram is shown in Fig. 1. TWO ternary intermetallic phases, designated w and

Jan 1, 1962

By D. M. Davidson, P. F. Kerr

The Permian Cutler Formation in Kane Creek, Utah bears uranium ore in fissure-type vertical veins. This fissure vein formation and its associated host rock bleaching, weak argillic alteration, and base-metal sulfide mineralization along with the development of hydrothermal minerals, a 60 m.y. isotopic Pb/U age, and well-crystallized uraninite's structural control, give evidence of ore deposition in a hydrothermal environment consistent with Laramide mineralization. Mica polymorph studies indicate first, that temperature during the hydrothermal alteration or subsequent ore deposition did not exceed 200°; hence Cutler deposits are classified telethermal; and secondly, that rock alteration and ore deposition are closely related both in time and space, as is seen in argillic alteration sequence. Ore deposition in an alkaline to slightly acid reducing environment is postulated. Ore textures and mineral associations and distributions also indicate that carbonate complexes may have been transported with the deposing ores. Bleached rock formations are not primary strati-graphic phenomena. Bleaching, or changes in ferric iron content, results from a chemical process involving reduction and conversion of hematite to a soluble aqueous ion. Nearby Chinle bedded deposits (Moss Rack sandstone), containing shale lenses, fossil wood, organic debris and minor fractures, overly the Cutler formation. Chinle ores have a single reported isotopic age of approximately 200 m.y. Their chemical environment is assumed similar to that of the Cutler ores, though slightly more acidic. Two genetic, paradoxically divergent interpretations of the bedded deposits are derived from available spectrographic, petrographic, X-ray and chemical analyses. Kane Springs canyon is located southwest of Moab, Utah, south of the Colorado River and northwest of the Lisbon Valley mining district (Fig. 1). Uranium deposits occur along the northeast flank of a Kane Creek salt anticline where two geologic formations bear ore, the Permian Cutler and the Triassic Chinle. The Cutler deposits' fissure vein formation is an unusual occurrence in the Colorado Plateau. The Chinle deposits appear to be of the normal sedimentary type. Associated with the vein deposits are a number of features, including argillic alteration of sedimentary strata. The minerals of these deposits and their associated features have been studied in detail in a two year program entailing both field and laboratory techniques. STRATIGRAPHY A stratigraphic section of the lithologic units in the Kane Creek area is given in Table I.

Jan 1, 1967

By R. E. Salvoti

IN underground coal mining, the increasing trend towards mechanical methods is ever apparent. Figures for 1939 showed that 28 per cent of the total bituminous coal production was mined mechanically 1940 statistic will reveal an even higher figure. Factors causing this trend are varied, but the important are the following;

Jan 1, 1941

By AIME AIME

PRESIDENT BASSETT'S gavel called the Annual Business Meeting to order shortly after 10 a. m. on Tuesday. On motion of Eugene McAuliffe, reading of the minutes was dispensed with and Mr. Bassett read his annual report of the year's activities as follows : During the year I have visited eighteen of the twenty- seven sections, making an average of GG 2/3 per cent. The invitation to come again has always been extended, but in only one case have I been able to visit the same section twice. Chicago entertained the president twice during 1930. Mrs. Bassett accompanied me on visits to ten sections. Everywhere we have found the most cordial hospitality and a gratifying enthusiasm for the Institute. If anyone had fault to find with the management or felt dissatisfied with what was being done, it was carefully concealed. I am happy to report to you an agreeable, helpful and progressive spirit in each of the sections visited.

Jan 1, 1931

By AIME

BORN in 1899, in Bridgeport, Conn., E. A. Anderson grew up in a center of the nonferrous metal industry. Perhaps that had something to do with his selection of mining as a career while an undergraduate in Yale. After securing his Ph.B. in mining he worked for a year at Handy & Harman. By this time physical metallurgy had supplanted his interest in mining and he entered the Yale graduate school where he secured his M.S. degree in metallography under C. H. Mathewson. After completing his graduate work he entered the employ of The New Jersey Zinc Co. in their research division where he has remained ever since. The transition from graduate study to industry involved no disruption of technical interests. Academic research relating to the zinc-aluminum alloys, then coming into use for die-casting, was followed by extensive and productive industrial research in the perfection and commercialization of these alloys. Research on rolled zinc and rolled zinc alloys, corrosion and stress corrosion, dry cells, electroplating on zinc, and electrodeposition of zinc followed in overlapping succession as time passed.

Jan 1, 1947

THE Pacific Northwest's joint meeting of the Industrial Minerals and Metals Branch in Spokane, Wash., drew 260 members, 72 students, and 30 ladies. Theme of the meeting was to acquaint men in the industry with students and younger men. The special appeal to the students was coupled with an attempt to attract young technical men from the companies located in the northwestern area. The activities of the meeting were available without charge to students. Contributions were made by the industries in the area to assist student attendance. Following the special student and faculty trip to the Trentwood rolling mills and research laboratory on Friday afternoon everyone enjoyed a complimentary dinner. A. Y. Bethune of the Sullivan Mining Co., spoke to the group on the operations of Kellogg, Idaho electrolytic zinc plant. The Industrial Minerals Div. session was opened on Saturday morning by R. G. Vervaeke, Conference Chairman who introduced A. O. Bartell of the Raw Materials Survey, Portland, Ore. Mr. Bartell in turn introduced C. W. Sweetwood who discussed Open-Pit Phosphate Mining.

Jan 1, 1952

By R. S. French, W. R. Hibbard

FOR tensile deformation, if the stress value is defined by the ratio of the load to the actual area, and the strain value by the natural logarithm of the ratio of the immediate length to the original gauge length of the sample, the resulting data when plotted with logarithmic coordinates result in a linear relation extending from the initial plastic yielding through the maximum load and in some cases, such as for copper and brass, to fracture'.'. The normal form of the curve, therefore, is a parabola, satisfying the following equation: S = Kem [1] where S and e represent true stress and strain, K is a constant, and m is a coefficient evaluating the slope of the curve and designated therefore as the strain hardening coefficient. Hollomon² has reported that this coefficient is a function of the yield strength as effected by grain size in alpha brass, and the carbon content and heat treatment of steel. In the case of steel, the value of the proportionality constant is a function of the carbon content. It was further shown in that paper2 and also by Low and Prater -hat, if the power relation between stress and strain remains valid, the strain hardening coefficient m, is equal to the strain at the maximum or necking load. Thus, an added significant feature is that this coefficient may serve as an index of the capacity for deformation prior to localized necking and subsequent fracture, e.g. drawability. The constant K may be defined as the strength of the material at unit strain. Together the K constant and the m coefficient describe an alloy's physical properties as far as strength and ductility are concerned for a particular yield strength and, in the case of steel, a particular carbon content. The work of Lacy and Gensamer4 gives data on alloy ferrites from which very close estimates of the strength of ternary and higher iron alloys have been made. It was the purpose of this investigation to develop similar data for commercial copper base alpha solid solution alloys. Preparation of Specimens Commercial binary alloys of copper with aluminum, beryllium, cadmium, nickel, silicon, tin and zinc were investigated. In addition, laboratory castings were made of a 1 pct silicon alloy and a 2 pct aluminum alloy to complete these particular series. Two types of copper were used, oxygen free OFHC and tough pitch FC. The analyses of these alloys are shown in table I. Standard ASTM sheet tensile specimens were used to determine the usual physical properties of each alloy and to obtain stress data at strains from 0.0005 to 0.01. Small (1/4 in. x 3 in. x tk.) samples

Jan 1, 1951

By T. L. Joseph

IT is a distinct privilege to participate in this meeting convened to honor the memory of Henry Marion Howe, a distinguished scientist and metallurgist. Many have added to our rapidly growing fund of metallurgical knowledge but few have made the unique contribution of formulating basic concepts essential to an over-all comprehensive view of the subject of metallography. Of those previously selected to deliver this lecture, several have added a personal touch to their discourse because they were able to refer to their associations with Dr. Howe. It was not my good fortune to know him or to enjoy his inspiring influence. Like most of you, my contact has been with his published works, which are outstanding in that they provide lucid, detailed expositions of the nature and behavior of metals and alloys. His deep understanding and clarity of expression have greatly accelerated our progress in metallography and in the use of metals. The degree to which a man's thinking, experimentation and writing contribute toward an understanding of basic laws and phenomena determines whether his life's work is of transitory or permanent value. This occasion appropriately recognizes the fundamental importance of Dr. Howe's pioneer work in the field of metallurgy. On two former occasions, gray iron was selected as a subject for discussion. The fact that the production of pig iron has not been discussed before does not reflect any lack of interest on the part of Dr. Howe or former lecturers in the process that under- lies the production of steel. Although Dr. Howe's work in his later years centered around metallography, his earlier publications show a considerable interest in the production of iron and steel. He recognized that in the ascending spiral of metallurgical advancement we are not winding a single thread but are weaving a complex fabric. Specific evidence of his interest in the production of pig iron may be found in his book1 on The Metallography of Cast Iron and Steel. In explaining why blast furnaces have been in constant use for about 600 years, he says: "The process is economical because it utilizes with extraordinary completeness the calorific power of the coke due to the thorough transfer of heat from the gaseous products of combustion to the charge." This emphasis on heat transfer, overlooked in many more extended and more recent discussions of the blast-furnace process, illustrates Professor Howe's ability to see the essentials. Other distinct advantages of the blast furnace, such as the removal of much of the sulphur and practically all of the oxygen, were mentioned. It was also stated that although the blast- furnace process is complex in nature, its outward form is comparatively simple, thus permitting large-scale production at small labor costs. All who contemplate the production of metallic iron from its ores by any other process might well consider the

Jan 1, 1946

By Frank T. Sisco

DURING the past year the iron and steel industry of the world as a whole operated on a satisfactory basis. No discoveries nor new processes of outstanding importance were announced either here or abroad, although rumors of such were persistent. In general, the efforts of operating and research men in the iron and steel industry seemed to be confined to improving quality and reducing cost, not a new aim, for the same efforts have been noted in nearly all of the annual reviews of the industry for at least fifty years. Most published papers on blast furnace or steel-making practice were of minor importance, at least when judged by the criterion of radical change in process or product. If the number of reports in the technical journals, or articles in the trade press, is used as a basis for comparison, continuous-mill sheet is still the most important single product of the industry; papers were published detailing the results of the investigation of various phases of the

Jan 1, 1938

A record $18.7 billion worth of metals, non- metals and fuels was produced in the U.S. during 1962, according to a year-end estimate from the USBM. The 1962 total value, based on preliminary statistics compiled by the Bureau, was nearly $600 million more than in 1961. Most minerals gained both in value and volume of production during 1962 according to information collected by the Bureau. All mineral fuels except anthracite showed increases. Among nonmetallic minerals- other than fuels-gains exceeded losses by two to one. Metal production held steady as gains and losses balanced.

Jan 2, 1963

By J. M. GLEDHILL

(Washington Meeting, May, 1905.) A Discussion of Mr. J. M. Gledhill's paper, read by title at the Lake Superior meeting, but presented first at the New Yolk meeting of the Iron and Steel Institute (October, 1904), and here published under a mutual agreement. Between the two Institutes. Discussion. MR. E: WINDSOR RICHARDS, Past-President, said that at a recent meeting of the Institution of Mechanical Engineers a paper was read on tool steel, and he called the attention of the members to the high-speed tool steel at the Bethlehem Works. They would have the pleasure of seeing those wonderful works and would see 60, 70, 80 and 100 tons oil lathe with half-a-dozen of these high-speed tools running. PROP. H. M. HOWE (Columbia University) said that they all looked upon these high-speed tool steels as of very great importance, particularly to the machine shop. One point occurred to hire : Had it really been shown that Swedish steel is necessary, or better than equally pure steel that is not Swedish; and is cemented steel really necessary, and is there any advantage in using that, rather than equally pure open-hearth steel'! It might be well if the author could indicate the kind of evidence on which lie bases his assertion that it is necessary to have cemented Swedish steel. Many were hoping for the development of high-speed steels from elements which exist in great quantities, such as silicon, manganese and chromium, rather than from rarer metals like molybdenum, vanadium and tungsten, the supply of which is likely to be soon exhausted. If the high-cutting speed was to last more than a generation, it. seemed to him that they would have to draw upon the common ele¬ments and not upon the rare ones. MR. Tom WESTGARTH (Middlesbrough) said he fully appreci¬ated what had been said about the advantages of using high-speed steel, because great benefit had been derived from the

Mar 1, 1905

By George W. Riter

(Canal zone meeting, November, 1910.) A DISTINGUISHED engineer, the active head of a large mining company, has said that surveying attains the dignity of a profession only in the hands of a few men-the few who know how to keep notes that will be understood by even a novice without further word of explanation. Of all mine-records, survey notes are perhaps the most important. The maps made from them serve as a working-guide, and as framework for other data ; and when, from any cause, access to underground workings is shut off, the surveyor's record often becomes invaluable. So seldom does a surveyor have a chance to check underground surveys by making a closure, that he is compelled to rely on the precision of each step of his work for the accuracy of the final result. When data are fully recorded on the spot, the notes, even in the hands of second parties, become evidence of the care and precision with which the surveying was done. It is worth a great deal to be able to pick up the work of a former surveyor where it was left o$; and to be able to carry it forward without retracing from the beginning. The purpose of this paper is to describe the survey-note system of a mine now under my direction, in which underground surveys had to be relied upon entirely for the proper division of rich ore-bodies between neighbors, thereby placing a premium on accurate surveying and permanent records. In survey-work, it soon turns out that paper is the least item of expense, and that little is gained by trying to economize note-book space. For many purposes it is best to record notes on cards or loose-leaves, which may be left in the office at the end of the day's work, and need not be carried into the mine again, there to become smeared with grime and grease. With the loose-leaf or card system, all notes relating to the same local-

Apr 1, 1911

By W. B. Tucker

UNUSUAL interest has recently centered in the Mojave mining district of California, owing to new discoveries of gold ore at the Silver Queen mine, and subsequently at other neighboring proper- ties. These finds have proved that opportunities exist for the prospector even in old mining districts, where careful search may still be rewarded. The Mojave district is characterized by a group of small hills centering around Soledad Butte, four to six miles southwest of Mojave, in Kern County. This butte is 1250 ft. higher than the surrounding desert and 4000 ft. above sea level. Four miles west of Soledad Mountain are the so-called Middle Buttes, a group of flat-topped hills. Gold was first discovered in the district in 1894, and the following productive mines developed: Queen

Jan 1, 1936

"World Mining and Metals Technology" is the title of this year's SME-AIME Fall Meeting and Exhibit in Denver, Sept. 1-3, where a record number of exhibits are scheduled for display. The international theme is particularly appropriate, for in addition to the annual SME session, the Third MMIJ-AIME Joint Meeting will be held.

Jan 8, 1976