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By Stanley Davidson

"The ore deposit mined by Falconbridge Nickel Mines, Limited, is one of the numerous nickel-copper sulphide bodies marginal to the large oystershaped mass of differentiated norite in the Sudbury district, famous as the world's most important nickel producing field. The unique character of the ore deposits of the district has resulted in its intensive geological study over a period of more than 50 years. The results of these studies have given rise to a voluminous geological literature and to a great deal of controversy as to the genesis of the ores. This description of the structural geology at the Falconbridge mine is presented in the hope that it may form a small part of the chain of evidence leading to a reasonably satisfactory explanation of the ore genesis.The mine, named after Falconbridge township in which the deposit occurs, lies along the southeast margin of the norite mass, which, however, is h::re concealed beneath a deep mantle of glacial sands and gravels averaging over 100 feet in thickness. As a consequence, the deposit was not discovered by the early prospectors, and it was not until 1916-17 that E. J. Longyear, of Minneapolis, located the ore by drilling(ll). The discovery was foreshadowed in 1899 by the work of Thomas A. Edison, who found indications of the deposit by what is believed to have been a combination of magnetic and electrical geophysical surveys. He sank a prospect shaft over what has to date proved to be the largest and richest ore section in the mine. A wet quicksand layer at the rock surface proved impenetrable, however, and the 'Edison' shaft never reached bed-rock.The Falconbridge property was acquired by the Lindsley interests in 1928, and ore output, since its inception in 1929, has gradually risen from a modest beginning to the present 2,000 tons and more daily. Total production in this period is 7,500,000 tons of ore averaging 1.72 per cent nickel and 0.89 per cent copper, together with a small but valuable content of precious metals, principally of the platinum group."

Jan 1, 1954

By M. M. Fine

A laboratory mineral-dressing investigation of manganese ore from the Martin mine, Independence County, Ark., succeeded in recovering ferrograde manganese products. Sintered flotation concentrates analyzing 40.7 and 41.4 percent manganese at overall recoveries of 54.6 and 47.7 percent, respectively, were produced from preconcentrated feed, Preconcentration of the ore for flotation included treatment by magnetic separation and by a combination of magnetic separation and heavy-medium processing. The mineral-dressing study of the Martin mine rhodochrosite ore was part of a general program of the Bureau of Mines to develop domestic sources of strategic minerals, including manganese. Several such potential sources of manganese exist in the Batesville, Ark., district, one of which is represented by the Martin mine. Although the Martin mine area has not been delimited with respect to total reserve tonnage, it is considered to be one of the more important occurrences of manganese in the district. It is estimated that several 100,000 tons of manganese carbonate ore are present in this and similar properties.

Jan 1, 1954

In preparing a paper such as this it was thought that the Newstan Colliery Company Ltd., being comparatively new, would need some introduction to mining people in general.The Newstan Company was formed by the Joint Coal Board in December, 1948 during a period of acute coal shortages. The Company took over the holdings of what were known as the Olstan and Northumberland Collieries, situated at Fassifern, alongside Lake Macquarie and adjacent to the Great Northern Railway, within easy rail access of Sydney and Newcastle, as shown on the locality plan (Fig. 1).The Company was developed in order to produce steaming coal for the power house trade and has continued its activities in the steaming coal trade since its inception. The Olstan and Northumberland collieries were together producing some 300 tons per day when the Company was formed, and it was from this foundation that the colliery was built. The planned development of the Company has been along the lines of producing coal by modern, highly mechanised methods, together with the preparation of theproduct for the consumer, to the highest degree possible consistent with up to date methods.In the comparatively short time of 5t years the mine has developed from a small hand-won coal unit to a high capacity modern mine, one of Australia's largest producers, with an output capacity as high as 3,000 tons per shift.

Jan 1, 1954

By Irving Hartmann

[The explosability of coal dusts has been the subject of many investigations studies have been conducted in laboratories, in galleries and in coal faire; of several countries to obtain information on the causes, development, and prevention of mine explosions. Early laboratory experiments on it American colas dealt with pressures developed in test bomb by explosions of dust clouds and with, the effects of gas in the dust atmosphere.5/ Later, the emphasis shafted to evaluation of the relative fleet flammability and the ignition temperatures of coal dusts.6/ Much worthwhile effort was devoted to the development of Laboratory apparatus and test procedures that gave good correlation with large-scale explosion tests in the Experimental cost mine. In recent years a number of special problems were studied, mostly with bituminous Pittsburgh coal dust]

Jan 1, 1954

By T. M. Morris

R. T. Hukki (Finland Institute of Technology, Helsinki, Finland)—Two schools of thought are developing concerning the order of the rate of flotation. The paper by Morris is intended to show experimental evidence in favor of the first order rate. Arbiter, on the other hand, has presented an earlier paper" to demonstrate the validity of the second order rate equation. Unfortunately his method of plotting is open to criticism, as pointed out by Morris." A more sensitive method of plotting has been described by the writer,= whereby the data presented by Arbiter demonstrate the superiority of the second order plot. The general rate equation may be written in the following forms for the integrated first and second order equations: (A) t = -1/k In Co-R/Co (first order) [4] 1 (B) 1/t = - kCo + kCo2 1/R (second order) As a first approximation the value of Co may be taken as a unity, 100 pct or 1. Whether or not this is the case in all tests performed by Morris is impossible to judge, owing to the fact that the flotation times are extremely short, e.g. 150 sec in tests A. It would, indeed, be very interesting to know what the total recovery R would be after 1 hr of flotation, for example, instead of after 150 sec. Certainly there are circumstances when C, approaches unity within a very small margin of error. Morris has used the same approximation in his example D "since the feed to this cleaner

Jan 1, 1954

By A. T. Coumbe

The first survey 3/ covering sales of liquefied petroleum gases was made in 1930 by the Bureau of Mines, which at the time was under the United States Department of Commerce. This original canvass covered national totals for 1922 through 1929, and most of the supply came from natural gasoline plants. The 1930 report showed approximate totals for butane and propane and for butane-propane mixtures and pentane grouped together. No attempt was made to breakdown the national sales by various uses until 1931, when the quantities for domestic or household consumption, gas manufacturing, and industrial requirements, including miscellaneous uses were indicated. As the market for these liquid petroleum gases expanded and as new uses came into importance, their respective quantities were shown separately in the annual survey. Sales for internal-combustion engine fuel and for raw material for chemical plants were first taken out of the industrial total in 1936. During World War II liquefied petroleum gases became important as feed stock diverted to synthetic rubber plants, and consequently the survey was broadened to cover this particular demand, beginning in 1944. Pentane was dropped from the survey after 1943, as, being liquid at atmospheric pressure, it is not considered as one of the liquefied petroleum gases and furthermore, the quantity reported made up less than 1 percent of the total sales. Thirteen producing companies reported to the Bureau in the first survey made in 1930, and in the 1952 canvass about 130 producers--petroleum refiners and natural gasoline companies--and about 1,300 dealers cooperated by filing schedules showing a breakdown of their sales. Their 1952 deliveries of approximately 4.5 billion gallons of liquefied petroleum gases were equivalent to about 3.4 billion gallons of gasoline or 3.1 billion gallons of distillate fuel oil.

Jan 1, 1954

By B. Welber, R. Webeler

A CCORDING to accepted theory, fatigue in A] metals is connected with the occurrence of local strain hardening even at applied stresses below the yield point as a consequence of stress concentrations created by the presence of structural inhomogeneities.1 It seemed possible, therefore, that

Jan 1, 1954

By K. B. Lindsey

Geologically, the Williston Basin is a large structural depression of sedimentary rock in Montana, North Dakota, and South Dakota and Manitoba and Saskatchewan, Canada. The approximate It-mite of the basin are shown on figure 1; it is roughly circular with a diameter of about 400 miles and contains approximately 120,000 square miles. Although the petroleum potentialities in this area had long been recognized, it had not been vigorously prospected by the petroleum industry because of its geographic location, rigorous winters, depths to possibly productive zones, difficult geological problems, and the fact that more seemingly favorable areas were available for prospecting. With the discovery of oil near Edmonton, Alberta, in the prolific Devonian reefs, an incentive was given to explore for oil in the southeast extension of the same sedimentary trough, the Williston Basin. The Virden field discovery in southwestern Manitoba in January 1951 was a direct result of this southeastward movement. Discovery of this shallow field was followed soon after by discovery of' deep production on the Nesson anticline in North Dakota at Clarence Iverson No. 1 well. North Dakota then became the twenty-seventh petroleum-producing State.

Jan 1, 1954

By H. M. Davis, J. H. Keeler

Densities of SAE 1020 (I) and ingot iron (II) decreased with cold rolling to minima at 60 pct reduction, whereas high-purity iron (III) was unaffected. I recovered promptly with annealing; II, sluggishly and incompletely. Hydrogen occlusion of III or II was barely affected by 60 pct cold reduction, but that of I was increased a hundredfold. IT has been reported of iron that its density is decreased and its occlusive capacity for hydrogen is increased by cold work. One of the most interesting aspects of each of these properties is that the changes brought about by cold work are not necessarily eliminated by annealing and recrystallization. Yet recrystallization is generally accepted as restoring to their original condition the properties or characteristics altered by cold work. A number of investigators have reported a decrease in density with cold reduction. Two1, 2 have shown that annealing after cold reduction may not return the density to its original value. It has been suggested' that cracks or flaws in inclusions produced during cold drawing contribute to the lowering of the bulk density of the metal. Extremely high-purity copper has been reported as not exhibiting a density decrease with cold reduction. On the other hand, calculations' indicated that grain distortion by itself can produce expansion of the order of magnitude of the changes observable. Maier" showed that both the density of iron and that of copper passed through a minimum with increasing cold reduction. Although much information is available on the subject of hydrogen in steel0, 7 and it is well known that plastic deformation of a metal may increase its occlusive capacity,8-12 most of the reports pertain to charging the metal with hydrogen by cathodic deposition or with acid. Darken and Smith,'" who employed acid charging, emphasized the great influence of cold work on the occlusive capacity of iron for hydrogen and showed the inability of a prolonged high-temperature annealing treatment to restore the occlusive capacity of cold-worked steel to the value exhibited in the hot-rolled condition. It has been reportedm that an "endothermic" metal*

Jan 1, 1954

By L. Stone, H. Margolin

The Ti-C-N and Ti-C-O systems were investigated in the temperature range from 500° to 1400°C and in the composition range up to 2 pct C and 5 pct N or 0. Characteristic isothermal sections at 800°, 900°, 1000°, and 1300°C are presented. The Ti-N-0 system was studied in the temperature range from 900' to 1400°C with alloys containing up to 6 pct total alloying content. Characteristic isothermal sections at 1000° and 140O°C are presented. Melting-point data for all three systems are also included. THIS paper reports on one of a series of investi-gations which have been conducted on the phase diagrams resulting from interstitial alloying with iodide titanium. The other investigations involved delineation of the binary systems with carbon,' nitrogen and boron,h and oxygen. The Ti-0 binary system has also been investigated by Bumps et al.' In varying degrees, each of these interstitial elements has been shown to stabilize the low temperature a modification of titanium1-5 and each forms a face-centered cubic TiX compound (henceforth designated 6). In addition, the Ti-N and Ti-0 systems reveal a low temperature tetragonal phase (6) formed by a peritectoid reaction between a and TiX Experimental Procedure The development of experimental techniques for the study of titanium alloy systems has, to a large extent, become standardized. In this investigation, the equipment and procedures described in detail by Cadoff and Nielsenl have been used. Arc Melting: In general, binary alloys with carbon, nitrogen, and oxygen, prepared in the composition range of interest in this investigation, show negligible composition changes during arc melting. However, the possibility of the formation of some gaseous combination of alloying elements such as CO, CN, or NO during the preparation of these ternary alloys was considered. Calculations showed that the evolution of only 0.05 gram of such a gas would be detectable as a pressure change in the closed system used during preparation of these alloys. Such pressure changes were not observed. Consequently, nominal compositions have been used in plotting the data. The compositions of the materials used in the preparation of the alloys are shown in Table I. After melting for 3 to 5 min at 275 to 350 amp, the alloys were checked for homogeneity by microstruc-tural examination. Alloys containing up to 1 pct C were homogeneous in the presence of less than 3 pct N or 0. At higher alloying contents, some inhomo-geneities in the carbon distribution became evident. Alteration of the melting procedure toward longer times and higher currents did not improve the homogeneity of these alloys. Ti-N-0 alloys were homogeneous in the range to about 3 or 4 pct total alloying addition. Beyond this, almost all of the specimens showed as-cast microstructures consisting only of the phase. Consequently, inhomogene-ities could not be detected by examination of micro-structures. Ten alloys from each of the systems were analyzed for two of the elements present (oxygen being omitted in all cases and titanium being omitted in the Ti-C-N alloys). In all cases the analyses were found not to be sufficiently precise to serve as criteria for the total composition of these alloys. On the basis of phase distribution in heat-treated alloys, however, it appears that carbon is distributed throughout the alloys most uniformly, with oxygen and nitrogen following in that order. Heat Treatment: Specimens for heat treatment were wrapped in titanium sheet before sealing in the argon-filled quartz capsules. Heat-treatment times varied from 100 hr at 800°C to 0.5 hr at 1400 °C. After heat treatment the specimens were quenched by breaking the capsule in water. With the exception of alloys in the low composition region, heat treatment did not have an appreciable effect on the as-cast microstructures. Metallography: Following heat treatment, the specimens were prepared for metallographic examination by grinding on emery paper and electrolytic polishing. For the majority of the specimens a 10-sec etch with Remington "A" agent (25 pct HNO3, 25 pct Hf, and 50 pct glycerin) adequately

Jan 1, 1954

By Rov G. Stott

In recent years there has been no loss of life from fires in the underground mines of the Lake Superior district, but numerous minor fires and several serious ones involving loss of property and production have occurred. The iron-ore-producing companies recognize that well-equipped mine rescue stations are a valuable asset against the ever-present ranger of mine fires or the possibility of hazardous atmospheric conditions underground. Prompt action by trained and properly equipped rescue teams is recognized as the prime essential in saving lives, property, and production when fires occur. To achieve this purpose, the mining companies have provided themselves with mine rescue equipment and maintain trained mine rescue crews. This circular describes how one progressive company has provided, maintained, and improved upon such protection for its underground iron-ore mines on the Marquette and Menominee iron ranges of Michigan's upper peninsula. SUMMARY The central mine rescue station of The Cleveland-Cliffs Iron Co. at Negaunee, Mich., has provided the company's mines with competent and well-equipped mine rescue teams. The new central mine rescue station at the Mather mine "B" shaft has the distinction of having underground training facilities provided as a part of the station. The company maintains the largest trained force in mine rescue in the Lake Superior district, and mine rescue training is employed as a part of the accident-and fire-prevention program. One of the most important results has been the promotion of closer cooperation and understanding between the management and the workmen. In addition to the service rendered to company mines, the station and its personnel have given assistance to others. The station and its equipment have also been used for training several nearby community volunteer fire departments. This mine rescue station and its personnel have been a dependable and valuable asset to the community in which it is located.

Jan 1, 1954

By Nordau R. Goodman

"IntroductionTHE HISTORY of Nova Scotia's gypsum industry goes back about two hundred years. The extensive deposits found in the Windsor formation, which is Lower Carboniferous, were the first discovered in North America and were known to the earliest .settlers. There has been a steady increase in production from these beds, except for minor setbacks in years of wars and depressions, but at the same time there has been a decrease in the number of operating quarries. This decrease reflects the change from the days of horse-and-cart recovery to the modern, large-scale, highly mechanized operations. In the beginning, almost any outcrop could •supply the tonnage requirements and the most •convenient were selected, but the millions of tons needed to meet present-day needs are not easily found.Despite the size and importance of the Nova Scotian deposits there has been little detailed geological work. Sir Charles Lyell, in 1843 ( 10), established that the beds are Lower Carboniferous and this was confirmed by Sir William Dawson (3) a .few years later. Both Lyell and Dawson agreed the calcium sulphate beds were an original part of a bedded series .but did not consider they resulted from a concentration of sea water. Lyell reached the conclusion that the gypsum was related to volcanic action in the form of heated vapours or hot springs. Dawson believed it was formed by the action •of sulphuric acid on calcium carbonate. The acid, derived from the oxidation •of iron pyrites which was abundant in the older formations, was carried by rivers into basins which were rich in shells."

Jan 1, 1954

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

Jan 1, 1954

By P. E. Busby, C. Wells, M. E. Warga

Fundamental data on the rate of diffusion of boron in austenite and solubility of boron in the a and y phases of iron and steel have been obtained from deboronizing experiments and provide partial explanations for some of the phenomena observed in boron steels. The rate of diffusion of boron is about the same as carbon in austenite. The solubility of boron in austenite at normal heat-treating temperatures is less than 0.001 pct. A partial tentative Fe-B phase diagram in the important low boron concentration ranges and an equation representing the diffusion of boron in austenite are presented. A LTHOUGH a search of the literature revealed ALTHOUGHthat boron diffusion had not been studied quantitatively and systematically prior to 1948, a few qualitative observations which were made by following the diffusion of boron into iron packed in ferro-boron1-3 suggest that boron obeys normal diffusion laws and that the rate of diffusion increases with increasing temperature. The claim of Cornelius and Bollenrath1 that boron does not appear to influence the rate of carbon diffusion has recently been substantiated by Wells, Batz, and Mehl.4 Calculations based on data from the paper by Campbell and Fayv indicated that the diffusion coefficient (D) for boron in iron at 900°C is approximately 3x10 sq cm per sec; a value of 2x10-7 sq cm per sec at 1038°C has been reported by Digges et al in connection with decarburizing experiments on a commercial boron steel containing 0.43 pct C. During the period 1948 to 1950 several diffusivity constant (D) values for the diffusion of boron in the y phase of iron and steel and a number of solubility values for boron in both a and y phases were reported. It was concluded tentatively as a result of Metals Research Laboratory studies that D values for boron in y and a phases are about the same as for carbon in the comparable phasesa and that carbon up to 0.4 pct did not affect the rate of diffusion of boron in y iron above 1000°C within the limits of experimental error. Whether saturation of the y or a phases with carbon would significantly affect rates of diffusion of boron through them was then and still remains in doubt. The best estimate of Q (activation energy) was reported to be about 25,000 cal, somewhat lower than that for carbon in y iron. The solubility of boron in y iron at 1000°C was thought to be higher than 0.004 pct B but not as high as a more recent analysis of available data shows it to be. The solubility of boron in a iron at 700°C was reported to be 0.0004 pct B, but it would not have surprised the authors if the true solubility value is actually lower than this. Breaks in diffusion curves which were not understood when first obtained prior to 1950 have now been recognized as indicating solubility limits, and these are included in the present paper. Experimental Procedure Two methods were employed in an effort to determine diffusion coefficients (D) for boron in austenite. Early experiments involved the use of welded couples prepared in accordance with the procedure of Wells and Mehl,' but when the results of these experiments proved to be unsatisfactory for calculating D values, studies were continued by means of deboronizing experiments. In both cases, boron analyses following the diffusion anneal were carried out spectrographically and all D values were computed using the Grube solution of Fick's law. The precision of the spectrographic method used proved to be about equal to that reported by Corliss and Scribner" —average deviation from the mean about 5 pct of the amount present when the boron content is 0.003 pct. Concentration-penetration curves obtained from spectrographic analyses of welded couples generally indicated that practically no boron was transported across the weld interface during the diffusion anneal. Furthermore the concentration-penetration

Jan 1, 1954

By W. Rostoker

IN the course of the development of the phase equilibrium diagram for the system Zr-Cr,' the structure of an as-cast allov having the composition ZrCr2 was analyzed and established to be isomorphous with MgZn2 (C14, hexagonal lattice, 12 atoms per unit cell). In a recent paper on the same system, Hayes, Roberson, and Davies' report for the ZrCr2 phase an isomorphy with MgCu2 (C15, cubic lattice, 24 atoms per unit cell). It appeared that this conflict might be resolved by assuming a high and low temperature modification for ZrCr2. That this was the case with the phase TiCr2 has recently been demonstrated by Levinger." Specimens of ZrCr2 annealed at 1200°, 1100°, 994", 900°, 834", 800°, and 700°C, respectively, and subsequently quenched were examined by X-ray diffraction analysis. It was successfully demonstrated that a transition from the MgZn, structure at lower temperatures to the MgCu, structure did occur at some temperature between 900" and 994°C. Table I lists the observed structures at the various annealing temperatures. In Table II, a summary of line spacings and intensities is given for each of the allotropic modifications. The first six lines of the MgCu2 structures have been located in the table to illustrate the close similarity between the patterns. Lattice parameters of the two modifications were calculated by a least squares solution of equations for interplanar spacings for a series of high angle lines. The results are as follows: MgZn2 type - c = 8.262 kX, A = 5.079 kX. MgCu2 type — a = 7.195 kX. It is interesting to note that TiCr2 behaves in reverse fashion yn that the MgCu, structure is the low temperature modification and the MgZn2 structure is the high temperature modification. References lR. F. Domagala, D. J. McPherson, and M. Hansen: This issue p. 279. 'E. T. Hayes, A. H. Roberson, M. H. Davies: Trans. AIME (1952) 194, p. 304; Journal of Metals (March 1952). 3B. W. Levinger: Trans. AIME (1953) 197, pp. 195-196; Journal of Metals (February 1953).

Jan 1, 1954

By Irving Hartmann

The fire end explosion hazard of excessive coal-dust deposits in mines has been recognized for many years, and important measures have been developed for reducing dust formation and to alley loose dust near its source. Nevertheless, in the course of normal mining it has been estimated that 1 to 3 percent (in some thin, friable seams up to 10 percent) of the total coal mined is reduced to dust of through-20-mesh fineness. In highly mechanized, continuous mining operations the production of fines is even greater. Most dust is trapped near its point of origin and removed from the mine, but large quantities are transported by the air current and by haulage into entries, where the greatest proportion settles on the floor and the balance on the rib and roof surfaces. The latter is generally finer in particle size than the floor dust; this, coupled with its more advantageous position for dispersion, makes the rib-roof dust (also to be referred to as overhead dust) a greater potential explosion hazard.

Jan 1, 1954

By Paul A. Taylor

MUCH information concerning pegmatites which was thought to be true a few years ago has been proved false, and what is now actually known about some pegmatites is not true of many others. The erratic and seemingly unpredictable structure and variable composition of this class of mineral deposits has been widely emphasized. Even parts of the same pegmatite body exhibit marked differences in texture, mineral composition, width, and attitude. Constructive geological thinking in respect to pegmatites now aims to establish general laws rather than to stress the confusing diversity of features having no special economic significance. Substantial progress has been made in classifying different types of these deposits according to general features, internal structure, mineralogy, and origin. In some cases it has even been possible to block out tonnage reserves in advance of mining. It is still easy, however, to make highly erroneous predictions after a preliminary examination of a pegmatite prospect. Pegmatites are important to the economic well being of the country and to its military security. They furnish virtually all the feldspar, strategic mica, beryl, columbium, tantalum, and caesium utilized in the United States, as well as sundry other minerals and significant amounts of lithium and rare earth minerals and gems. With the exception of vermiculite, occasional ilmenite-rutile, and perhaps soda-lime feldspar and garnet deposits, basic pegmatites are of little economic importance. Consequently in this paper, as in common parlance, the term pegmatite generally relates to coarsegrained acidic rocks or what is aptly called giant granite. Available data indicating the size and importance of the production and trade in specified pegmatite minerals are summarized in Table I. Geological Features Much of the latest thinking on the economic geology of pegmatites is now available in a 115-page monograph' by a group of experts who participated with geologists of the Federal Geological Survey in the widespread wartime investigations. Doubtless the most significant feature of the monograph is indicated by the title, The Internal Structure of Pegmatites, but it also contains a vast amount of other new information and includes the assimilated concepts of many earlier writers, whose works are given in a comprehensive list of references. The shape, size, attitude, and continuity of many pegmatite bodies is controlled by the structure of the older rocks in which they occur. If the older rocks are easily penetrated, e.g., biotite schist, most of the pegmatites in a given district will be found outside the parent granite mass as exterior pegmatites. Marginal pegmatites are more prevalent if the older rocks are massive, unsheared, and sparingly jointed. Networks of pegmatites are abundant in highly-jointed rocks. In strongly foliated schists the bodies are usually lenticular, whereas in highly-folded areas they assume tear drop, pipe or pod-like, bow-shaped, or sinuous forms. Jahns2 recognizes five major shape classes: l—dikes, sills, pipes, and elongate pods; 2— dikes, sills, pipes, and pods with bends, protuberances, or other irregularities; 3-—trough-or scoop-shaped bodies with or without complicating branches; 4—bodies with the form of an inverted trough or scoop; and 5—other bodies, including combinations of the above and miscellaneous shapes. Many pegmatite deposits are scarcely big enough to be recognizable as such. Most of them, in fact, are small tabular deposits less than 4 in. wide and usually without economic concentrations of minerals. On the other hand, some pegmatites are more than a mile long and over 500 ft wide. The ratios of length to breadth range from 1 : 1 to 1 : 100. Although the vertical dimension bears no invariable relationship to strike length, tabular deposits or large lenses are often symmetrical enough to show nearly as much continuity down dip as in their horizontal extension, and some pipes or pods are amazingly persistent in the vertical plane. Small pegmatites often string along a fairly definite trend line; in a given district major bodies may lie roughly parallel, and where only a few of them do not, the erratically disposed bodies generally differ in composition from those conforming to the regular pattern. This does not apply, however, in all districts. Characteristically, pegmatite veins pinch and swell or split into branches. When they pinch out entirely it is often possible to find a new body by prospecting the extension of the strike or dip, but the chances of finding a hidden deposit are ordinarily too uncertain to justify much subsurface prospecting. Diamond drilling may yield valuable information as to the continuity of known deposits whose upper portions are well-exposed. Some deposits, in fact, can be proved up for hundreds of feet by surface trenching and then intersected by drill holes at various depths like any other vein-like deposit. Others twist and branch, apparently defying all efforts to explore them short of actual mining.

Jan 1, 1954

By D. L. Rainey, E. R. Goter, W. R. Hudspeth

THE area in which spodumene-bearing pegmatites occur extends from Gaffney, S. C., in a northerly direction to Lincolnton, N. C., a distance of about 16 miles. The zone averages 2 miles in width. Interest in this area was first aroused by the discovery of small amounts of cassiterite in the peg-matites and in greissen which occurs on the walls of some of the pegmatites. Attempts were made from 1880 into the 1920's to mine and concentrate cas-siterite, but there were no successful operations. In 1935 L. M. Williams became interested in the area and began prospecting by trenching and sinking several small shafts. He gradually gained control of a considerable acreage south of the city of Kings Mountain, N. C. Mr. Williams states that he produced some ore from a shaft which he shipped to the Maywood Chemical Co. in the late 1930's. In 1937 G. H. Chambers of the Foote Mineral Co. visited the area and examined several properties, but the lithium market was too small to support the necessary concentrating plant. Early in World War II the Solvay Process Co., encouraged by various federal agencies, acquired the Williams properties and leases and started a drilling program to develop reserves for spodumene mining. A study of this area was also made under T. L. Kesler by the U. S. Department of the Interior Geological Survey. Starting in 1942 a concentrating plant, water supply dams, and shops and other buildings were constructed. The Superior Stone Co., a neighboring crushed stone operator, was awarded a contract to mine and crush the pegmatite ore. Late in 1943 the plant started operations, which were continued until February 1946. A drop in demand for lithium chemicals forced it to close and remain closed for several years. In 1948 the Foote Mineral Co. became interested in assuring itself a source of lithium ore on the North American continent, to be used in the production of lithium ore chemicals, and inspected properties in Canada, South Dakota, and North Carolina. The North Carolina deposits were the most promising. In the fall of 1950 the company leased the Solvay interests with option to buy and acquired additional properties. Renovation of the mill and preparation of the quarry for mining was begun in earnest in January 1951. A new crushing plant was built and construction started in July 1951. The flotation process used was developed in the North Carolina State Minerals Research Laboratory located at Asheville, N. C. Foote is now in the process of expanding its production. The crushing plant is being revamped and much of the old milling equipment purchased from Solvay will be replaced by new. Mining equipment of suitable capacity has been received and is in use. The frontispiece is a general view of the mill. The orebodies consist of pegmatite dikes composed of fine-grained albite and quartz, with varying amounts of mica and spodumene. The latter may amount to as much as 50 pct of the rock, but the overall average is about 15 to 20 pct. Tin, columbite-tantalite, beryl, and other valuable minerals are present in varying small amounts. These dikes, which intruded into the Roan Gneiss underlying most of the Piedmont area, strike approximately N 30 E and dip about 85" to the west. The gneiss has the same strike but dips about 70" west. The dikes lie in a belt extending from Lin-colnton, N. C., to Gaffney, S. C., and passing through

Jan 1, 1954

By A. G. Metcalfe

Observations at temperature are used to investigate the phase changes in alloys containing more than 50 pct Co and above 1000°C. The nonsuppressible transformations in cobalt above 1120°C and in the intermetallic compound Co2Cr3 are studied. The liquidus and solidus surfaces are determined. Insufficient data is obtained to complete the constitution diagram. A REVIEW of some of the earlier work on cobalt' and on the binary systems with chromium2-4 and with molybdenum,5 showed that one likely source of differences might be attributed to the presence of phases at high temperatures which could not be retained by quenching. Consequently, the decision was made that only methods of examination at temperature should be used in this work. The correctness of this decision was confirmed during the course of the work by the investigation of the martensitic nature of the transformation in cobalt- and by the decomposition of the high temperature form of the phase Co2Cr3 on quenching.' The use of high temperature methods, including dilatometry and thermal etching led to the postula-tion of the existence of a high temperature form of cobalt with a probable hexagonal close-packed structure, transforming from cubic cobalt over a range of temperature from 1119° to 1145°C.8 One of the important pieces of evidence for this transformation was that it was observed in alloys with chromium and molybdenum which were nonmagnetic at this temperature so that confusion with magnetostriction effects was impossible. These results were not reported in this earlier paper, so that the data given here supply further evidence for the existence of a second allotropic transformation in cobalt. High temperature observations are necessarily much slower in producing results than the examination of quenched specimens at room temperature by conventional means such as X-ray diffraction or microexamination. The investigation has only covered a limited part of the field, as a result, extending from the liquidus down to about 1050°C and from the cobalt corner up to 50 pct alloying elements. The differences between the various reported diagrams for the constitution of the Co-Mo and Co-Cr systems have already been mentioned. The best available diagram in the first system is due to Sykes and Graff' which is shown in Fig. 1. Fig. 2 shows the latest Co-Cr diagram due to Elsea, Westerman, and Manning.' A comparison reveals that these are incompatible because of the disagreement with regard to the number of allotropes of cobalt. Elsea, Westerman and Manning took their liquidus and solidus curves from Wever and Haschimoto.2 The temperature horizontal in the two-phase field beneath the eutectic was placed 35" to 39°C higher than in earlier work2,4 with a new interpretation of the nature of this transformation. This interpretation also required a peritectic horizontal at about 1470°C, which has been confirmed here for an alloy with 53 pct Cr. No investigation had been made of the ternary system until after this work had been terminated, when a section at 1200°C was published." In this work a ternary compound was found by the X-ray diffraction examination of quenched alloys. This compound contained less than 50 pct Co, and was thus outside the field investigated here. However, some reactions were found dilatometrically which could not be fitted on the diagram and are now believed

Jan 1, 1954

By H. S. Bostock

"The study of the geology of Mayo district began in 1900 with R. G. McConnell's exploration of Stewart river; and has been carried on intermittently for the Geological Survey of Canada by J. Keele; D. D. Cairnes; W. E. Cockfield; C. H. Stockwell; and the writer. It has revealed a thick group of schists; quartzites; and crystalline limestones; almost certainly Precambrian in age; placed in the Yukon group; and a group of younger intrusive igneous rocks varying in composition from granite to gabbro. These include bodies of many sizes and forms; from stocks 8 miles across to small dykes and sills.Prospecting in the district began about 1897 and has disclosed the presence of gold, silver, lead, tungsten, tin, zinc, antimony, copper, arsenic, manganese, and mercury, both in placer and lode deposits . Of these metals gold, silver, and tungsten have been produced from placer deposits, and silver, lead, and gold from lodes. This paper deals only with some structural relationships of the lode deposits, generally referred to as the silver-lead veins, which have yielded the greater part of the mineral production of the area. From 1938 to 1941 the geological mapping of the district for publication on a scale of 4 miles to 1 inch was carried out by the writer, and the ideas expressed here are based on this work. No comprehensive detailed study of the silver-lead veins has been made, but the mapping has brought to light several important facts. The rocks of the Yukon group, although of a striking sameness throughout their section, can be divided into a number of distinguishable members by means of which the main structures can be traced . The most important and readily distinguishable rock in the group is referred to here as the quartzite member. This is composed of quartzite and schist in about equal proportions. The quartzite is resistant to erosion and forms most of the outcrops of the'member and the peaks of the Gustavus mountains and mount Haldane (Lookout)."

Jan 1, 1954