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By F. G. Coggin

" If you could only get that motion into a machine," said a gentleman, as he watched the process of making a " van " on a shovel, and saw the copper roll up to the highest point, "it would beat the world for slime-dressing." This idea has led to many an effort to get into a machine that peculiar motion, called the " vanning motion;" and so cams, eccentrics, eccentric gears, levers, bell-cranks, togglejoints, links, springs, etc., have been brought into requisition, while a contribution has been laid upon all the conceivable motions, rolling, tumbling, swinging, jerking, tossing, dropping, tripping, intermittent, regular and irregular, or a combination of some of them, to which have been added percussion, concussion, and more discussion —all in a vain attempt to combine in a single machine the consecutive motions of the shovel, in washing, flowing, and tossing the van. The Patent Office Reports, and the various mills of the country, show, as a result of this, a lot of gimeracks, most of which never went beyond a first trial, finding their way to the scrap-heap. Others still running might as well be there; while some have considerable merit for dressing other and richer sands than copper. It does look tempting to see that clean edge of copper climbing up the shovel-blade; but those who have seen in it such visions of large fortunes have not considered the time it takes to make a van, compared with the small quantity treated upon the shovel; and this points to the reason for the failure of all that class of machines called " vanning machines," when used for dressing copper slimes, namely, a lack of capacity. The writer has come to this conclusion through an experience with the Rittinger side percussion-table of the most improved make, sent from Germany to the Calumet and Hecla Mining Company, and with the Ellenbecker tables, used by the same company, both of which are good types of that class of machines. In both of these machines, the tables are suspendetl by rods which allow them to swing, and they can also be adjusted for the purpose of varying the inclination of the table. In the Rittinger machine, the motion of the table is at a right angle to the flow of the slime, being produced by a wiper-cam which throws the table against a spring, which throws it quickly back against a stop, the percussion throwing up the mineral. In the Ellenbecker table, the motion is

Jan 1, 1884

By Waldemar Gooskov

IN his well-known work,1 published in 1867, P. Ritter von Rittinger gives the following formula for the velocity of a particle settling in still water: v=C/D(a -1) and for average grains he assigns to the constant C a value of 2.44. As is well known, the value of C depends on the shape of the grains resulting from crushing, and it is obvious that values obtained for coal particles will not only be very different from those for ore particles but will even be characteristic of coal from a certain seam. The only way of finding an accurate value of C, applicable to conditions in Russia, where all coal-washing plants are built on German principles, is to conduct a series of tests of which the results will determine what value of C is to be used. In the investigation outlined in this paper the theories of Prof. Robert H. Richards2 were taken as the basis of the tests; the slimes were removed from the charges to eliminate the trouble of handling them; and to obtain accurate results free from errors inevitably resulting from human observation, photographic apparatus was used and a series of pictures taken which form the basis for constructing a suitable diagram of velocity vs. time.3

Jan 1, 1928

By James Norman

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each of clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1940

By J. R. Thoenen

IF ASKED whether limestone production was a mining problem I would; not hesitate to answer emphatically in the affirmative. The question, "When is a quarry a mine?" is familiar. The immediate mental picture induced by the thought of limestone production is that of an open quarry. All are familiar with the open pit in the iron-producing districts of Minnesota and Michigan and the open cuts of the so-called "porphyry" coppers of the West. If these are mines, they differ little from limestone quarries in general mode of operation; if quarries, why do they need the attention of mining engineers? During 1923, the United States produced in round numbers 70,000,000, tons of ore. The limestone production of the United States for the same period was something over 100,000,000 tons. In tons, it about equals the oil production of the United States. The uses of limestone are legion. A paper read by a prominent engineer of Chicago, at the meeting of the National. Crushed Stone Association held last February in St. Louis says: "There is no industry in the United States today that is more basic in its operation or by itself controls. more industries. There is hardly a chemical operation, hardly a metallurgical operation or building operation that a crushed-stone man does not control if he will jump in and make the full utilization of it." Some of the many uses are for road metal, concrete, railway ballast, building stone, riprap, and rubble, the manufacture of iron and steel, alkalies, calcium carbide, magnesia, carbolic and carbonic acids, asphalt filler, mineral wool, poultry grit, sulfuric acid, phosphates, nitrates, soap, baking powder, the purification of copper and prevention of coal-mine explosions, to say nothing of the quantities used in the making of lime and cement. It has been said that without iron we would revert to the Stone Age; how much iron would we have without limestone? From the point. of view of the mining engineer, using the term in its broad sense to include geologists and metallurgists, the production of limestone is important because of its occurrence, volume, commercial importance, and the problems presented by its recovery and treatment.

Jan 2, 1925

By A. Hultgren, B. Herrlander

The original aim of the present investigation was to study the mechanism of cracking on hot-deforming red-short steels. During the microscopical examination of hot-deformed soft steels attention was directed to various patterns of so-called veining in the ferrite, as related to variations in the deformation procedure and the heat-treatment of the steels. Later, a hot-short steel of higher carbon content was also studied. Historical Storey1 suggested in 1914 that veining developed during the gamma-alpha transformation from the growing together of several alpha nuclei within the same gamma grain. Rawdon and Berglund2 found that in soft steel, forged somewhat below A3, the ferrite showed profuse veining, while usually there was very little veining after forging at very high temperatures. They emphasized the similarity between the pattern of veining formed by deformation about 600°C and that of slip lines formed by deformation at room temperature. They also suggested a relation between the gamma-alpha transformation and veining. They became convinced from etching and from the slip-line pattern in cold-deformed material, that the orientation within any ferrite grain showing veining was uniform. In recrystallized alpha grains veining was absent. Veining did not appear materially to affect the properties of ferrite. Independent of veining, continuous networks, attributed to preexisting delta and gamma grain boundaries were sometimes found, the former only in cast steel. Those networks were usually connected with small inclusions. Ammermann and Kornfeld3 confirmed that recrystallized ferrite grains showed no veining. In soft steel annealed between A1 and A3 there was veining only in the ferrite grains formed during cooling. Electrolytic iron deformed at 880' was free from veining. Bannister and Jones' considered veining in ferrite to be a manifestation of microscopical and sub-microscopica~ inclusions. NorthCOtt,5,6 in studies on veining in steel and other metals and alloys, attributed veining to oxide inclusions. It could generally be removed by annealing in hydrogen, a suggestion earlier made by Rawdon and Berg1und. TrittOn (discussion in ref. 5) emphasized the importance of perfect polishing for bringing out veining by etching, and thought the veins or subboundaries were produced during the gamma-alpha transformation, when it was rapid, as a result of the volume change and contraction during cooling. Slight distortion would not allow projecting parts of a growing crystal to join up with atomic symmetry. Hanemann and co-workers showed that veining in ferrite consisted of ridges

Jan 1, 1948

By B. Herrlander, A. Hultgren

The original aim of the present investigation was to study the mechanism of cracking on hot-deforming red-short steels. During the microscopical examination of hot-deformed soft steels attention was directed to various patterns of so-called veining in the ferrite, as related to variations in the deformation procedure and the heat-treatment of the steels. Later, a hot-short steel of higher carbon content was also studied. Historical Storey1 suggested in 1914 that veining developed during the gamma-alpha transformation from the growing together of several alpha nuclei within the same gamma grain. Rawdon and Berglund2 found that in soft steel, forged somewhat below A3, the ferrite showed profuse veining, while usually there was very little veining after forging at very high temperatures. They emphasized the similarity between the pattern of veining formed by deformation about 600°C and that of slip lines formed by deformation at room temperature. They also suggested a relation between the gamma-alpha transformation and veining. They became convinced from etching and from the slip-line pattern in cold-deformed material, that the orientation within any ferrite grain showing veining was uniform. In recrystallized alpha grains veining was absent. Veining did not appear materially to affect the properties of ferrite. Independent of veining, continuous networks, attributed to preexisting delta and gamma grain boundaries were sometimes found, the former only in cast steel. Those networks were usually connected with small inclusions. Ammermann and Kornfeld3 confirmed that recrystallized ferrite grains showed no veining. In soft steel annealed between A1 and A3 there was veining only in the ferrite grains formed during cooling. Electrolytic iron deformed at 880' was free from veining. Bannister and Jones' considered veining in ferrite to be a manifestation of microscopical and sub-microscopica~ inclusions. NorthCOtt,5,6 in studies on veining in steel and other metals and alloys, attributed veining to oxide inclusions. It could generally be removed by annealing in hydrogen, a suggestion earlier made by Rawdon and Berg1und. TrittOn (discussion in ref. 5) emphasized the importance of perfect polishing for bringing out veining by etching, and thought the veins or subboundaries were produced during the gamma-alpha transformation, when it was rapid, as a result of the volume change and contraction during cooling. Slight distortion would not allow projecting parts of a growing crystal to join up with atomic symmetry. Hanemann and co-workers showed that veining in ferrite consisted of ridges

Jan 1, 1948

By R. B. Schluter, M. M. Fine

The Bureau of Mines' Twin Cities Metallurgy Research Center has of late concerned itself with reduction-induration of iron ore. One development provided a flowsheet for the agglomeration of green concentrate pellets in a reducing atmosphere created by a solid reductant external to the agglomerate. The product pellets were well metallized and physically competent. Maximum recommended operating temperature was 2100º F. In these studies, it was observed that unflred iron ore pellets indurated in a bed of anthracite or certain lignite chars frequently acquired exceptional crushing strength. A diagnosis of the phenomenon revealed that sulfur in the fuel was the probable cause. Accordingly, a research program was established to test this premise and to put it to practical use. Gaseous reductants were employed initially because of the ease and accuracy with which they could be metered.

Jan 10, 1969

By Cadwallader Evans

THE American Institute of Mining Engineers was organized in the anthracite region of Pennsylvania by men who were primarily interested in anthracite. Its first meeting, at Wilkes-Barre, Pa., in the Northern Anthracite field, on May 16, 1871, resulted from a call sent out by three outstanding men of the anthracite .industry: Eckley B. Coxe, R. P. Rothwell, and Martin Coryell. The best known of these was Eckley B. Coxe, who was the manager of large hold¬ings operated by him and his family,. and who is remembered as the inventor of a special grate for burning very fine anthracite, known as the Coxe traveling grate, which is still very widely used. R. P. Rothwell was a well-known consulting engineer of the region, as was Martin Coryell, who was associated with another well-known anthracite family, the Pardees. There is no record of the discussions that resulted in this initial meeting, but it is safe to assume that the formation of the Institute was largely influenced, through appreciation by the founders, of the necessity for a free exchange of information covering the whole of the mining industry. One of the rules adopted at the first meeting was:

Jan 1, 1947

By Colin G. Fink, Leslie G. Jenness

Tantalum and columbium occur together in tantalite and columbite ores, which may be considered as ferrotantalate (FeTaz06), with part of the iron and tantalum replaced by manganese and columbium respectively, the general formula, therefore,becoming (Pe, Mn)O.(Ta, Cb)2Os. The ratio of tantalum to columbium is not fixed; the amount of tantalum may vary from one-third to three times that of columbium. Minerals having a high content of tantalum are called tantalite, while those possessing larger amounts of columbium are classified as columbite ores. These minerals are found in pegmatites and often occur in veins associated with cassiterite and wolframite, and may contain small amounts of tin, tungsten, titanium and si1ica. l Methods of Extraction Several methods have been proposed for the extraction of tantalum and columbium from their ores, among them being: 1. Fusion with Potassium or Sodium Bisu1fate.—The finely ground ore is fused with potassium bisulfate, after which the mass is boiled with water and the fusion repeated several times. The residue finally resulting is digested with ammonium sulfide to remove traces of tin and tungsten, boiled with hydrochloric acid, filtered and washed. These oxides are then dissolved in hydrofluoric acid, the silica evolved as silicon tetra-fluoride and the hydrofluoric acid solution used for the potassium double fluoride separation of tantalum. 2. Fusion with Sodium Carbonate and Sodium Nitrate.2—This fusion renders the tantalum and columbium soluble, and they are extracted

Jan 1, 1931

By A. F. Lucas

The rock-salt deposit of Petite Anse, in Louisiana, has been known for many years. A description of it, with an account of the method pursued in its exploitation, was contributed in 1888 to the Transactions of the Institute* by Mr. Richard A. Pomeroy. But this locality does not by any means comprise the whole of the resources of the State in rock-salt. A few months ago the writer published a general account + - of all the Louisiana localities now known, together with particulars concerning their technical and commercial development. In view of the fact that active enterprises in this line have increased in number, and promise to constitute an important, if not controlling, factor in the supply of salt for the immense demand of the United States (including, as it does, the consumption of this mineral as a raw material in chemical manufactures), the present paper has been prepared. While it necessarily contains much of the substance of the article above mentioned, it is accompanied with illustrations and details not heretofore published. Moreover, the former article is out of print, the publishers having no copies left of the number of their journal in which it appeared, and the writer is therefore warranted in the belief that a paper placing the essential facts on record in a form more permanently accessible to mining engineers will be acceptable to the members of the Institute.

Jan 1, 1900

By E. J. Dulis, R. M. Fisher, K. G. Carroll

IT is well known that ferritic steels containing more than 15 pct Cr when subjected to temperatures in the range of 700" to 1000°F exhibit increasing hardness and decreasing ductility. The phenomenon has been widely termed the "885 °F embrittlement," after the temperature of most marked effect.'.' In view of the excellent review articles available in the literature3-6 only a brief account of experimentally established facts need be given here. The extent of changes in physical characteristics during embrittlement depends on chromium concentration and time at temperature, higher alloy content and longer time both promoting more rapid and extensive changes. In a 27 pct Cr steel, changes in impact strength and in angle of fracture in bending can be detected after only a 1 hr exposure at 885°F; after 50 hr this steel becomes quite brittle. Hardness increases slowly with time during thousands of hours exposure and may attain a maximum hardness number twice as large as that of the unexposed steel. Microstructural changes accompanying embrittlement have been described as an initial widening of grain boundaries followed by eventual darkening of ferrite grains. Embrittled steels etch more readily, e.g., the weight loss of a 27 pct Cr steel in acid solution may occur at a rate one hundred fold greater following exposure at 885 OF. Marked changes which accompany embrittlement have been observed in electrical resistivity, specific gravity, and magnetic coercive force. Changes in physical properties may be readily removed by heating at temperatures above the embrittling range, such as a treatment at 1100°F for 1 hr. It has frequently been noted that the 885 °F embrittlement suggests precipitation on a submicro-scopic scale of a chromium-rich constituent, the nature of which has not been revealed by X-ray diffraction. Progressive broadening of the body-centered cubic diffraction lines during embrittlement has been observed," and recent observations by Lena and Hawkes' upon single crystals have shown early asterism in X-ray photographs, disappearing within an hour at 900 °F. Many workers have ascribed8-13 the phenomenon to a precipitation of a phase (FeCr), which is known to cause embrittling effects at temperatures much higher than 885°F. Two general observations, however. suggest that a precipitation cannot be responsible for the 885°F phenomenon: 1—prior cold work greatly enhances a formation, whereas it scarcely affects the 885 °F embrittlement, and 2—the presence of an alloying element such as nickel or manganese may have an effect on the 885 °F embrittlement which is opposed to its effect upon a formation. The slight enhancement of a formation and 885°F embrittlement observed in the presence of elements with strong carbide and nitride forming tendencies' is probably a consequence of lessened chromium depletion of the matrix. The bar graph in Fig. 1 shows a typical example, taken from two 27 pct Cr steels used in this work, of the hardness after exposure for 10,000 hr at 900°, 1050°, and 1200°F. Steel A (0.03 pct C, 3.13 pct Mn) showed marked hardening at 900" and 1200°F, whereas steel B (0.12 pct C, 0.63 pct Mn) exhibited only the 900°F hardening. The cr phase was found in steel A at the higher temperatures but not in steel B. Presumably a formation is enhanced by the low-carbon and high-manganese concentrations in A," Thus there are two distinctly different hardening phenomena present which cannot both be ascribed to v precipitation without invoking a transition phase possessing remarkable properties. Materials A number of chromium steels exposed for long periods (5000 to 34,000 hr) at 900°F, as well as unexposed samples of one of the steels, were available for this investigation. Table I gives the chemical compositions and aging treatments of these steels. In addition to these steels exposed in the elevated temperature test furnaces of the National Tube Division, a number of high-chromium steels were heated for short periods in small laboratory air furnaces and lead baths. Supplementing these commercial steels, a sample of high-purity (0.018 pct C, 0.002 pct N) 28 pct Cr iron, exposed 1000 hr at 887°F. was furnished by the Union Carbide and Carbon Corp. In addition, an alloy of iron and chromium of high purity containing 46 pct Cr was used. This

Jan 1, 1954

By Richard Amberg

While the old-time melter was satisfied to bring his metal out in the desired condition, and therefore took care to have the slag liquid enough, the importance of a thorough knowledge of the slag is at present recognized in all up-to-date melting-shops. Formerly slag or cinder was considered a necessary evil, accumulating in some mysterious way wherever a man was striving to produce a clean metal. Nowadays we deliberately aim at a well-defined slag, which varies with the nature of the process and the product. In steel-making we need slag for two main purposes, namely, refining and protecting the metal. To refine metal, essentially oxidizing and reducing processes are required, while to protect the metal we need a reducing or, still better, a neutral atmosphere. Although an absolutely neutral condition between steel, on one side, and the containing vessel and the slag, on the other, is an imaginary conception, the various furnaces in use for the production of liquid steel maybe arranged with respect to the attainment of this ideal in about the following order of merit: converter, open-hearth, crucible, and electric furnace. In dealing with the subject we will find it convenient to avail ourselves of the terms of physical chemistry, which yield a simple conception of the matter and an expedient way of expression. Slag and metal at large are not mixable with each other, and we will therefore call them the two " immiscible phases," though there are certain compounds which dissolve in both phases under conditions to be considered later. Reactions be-

Jan 1, 1913

By Marcel Daly

IN a preceding paper 1 the writer has pointed out some apparent relationship between the distribution, on the Surface of the globe, of the known hydrocarbon deposits and the disposition of the principal zones of deformation of the earth's body (geosynclines). He wishes to present some further remarks on this subject. Petroleum deposits, or their derivatives or descendants, are found through the whole range of sedimentary strata, from the pre-Cambrian to the Quaternary. For instance, the pre-Beltian (Shuswap) series of the Canadian Cordillera are interbedded with limestones which are sometimes rich in carbonaceous matter (Sicamous limestone) ; and the Beltian system of the same region contains layers of argillites and dolomitic limestones which are equally high in carbon content.2 This carbon may be interpreted as the last remnant of hydrocarbons previously contained in the rocks. On the other hand, the actual formation of hydrocarbons wider conditions that would eventually permit their deposition in modern sediments is conceded by some geologists.3 Between these two extreme limits, bitumens are found indifferently in all sedimentaries. They constitute a continuous series, some kind of a large family, whose individual members may be entitled to a community of origin and probably represent the differentt stages of evolution of the primitive, parent matter. . The kinship between petroleum and such substances as asphalt, ozocerite, manjak, grahamite, albertite, etc., is well known; and E. H. Cunninggam-Craig has recently shown how intimately shale fields and oil fields are connected. For this reason, no distinction is made in the present

Jan 8, 1917

By William H. Callahan

"For his exceptionally successful career as a geological mentor, for his ore-finding skills, and particularly the discovery of the Central Tennessee Zinc District and for his lecture, 'Prospecting in the USA-Promise and Problems.' " Recipient of the 1982 D.C. Jackling Award

Jan 1, 1983

By C. W. Hall

Owing to its isolation and comparatively small tonnage, the Yoquivo district is not widely known; though financially important and, geologically, quite interesting. San Francisco dc Yoquivo, the center of the mining district, is in the western part of the state of Chihuahua, Mexico; about 35 miles west of. San Juanito, on the Kansas City, Mexico & Orient R. R. The town can be reached from the railroad by a good trail over a rugged country. The elevation of Yoquivo is 6500 ft., and peaks surrounding the town are 2000 ft. higher. The mining towns of Concheno and Ocampo are 25 miles northwest, and Uruachic is 20 miles southwest. The climate, temperate and healthful, is almost ideal. The rainy season begins in July and ends the latter part of September. There is usually, though not always, some precipitation in all months except April, May, and June: The mountains are covered with pine and scrub oak. Water, wood and lumber are plentiful for all ordinary purposes, and hydroelectric power is available for. about six months of the year, when wood for steam, power is utilized as an expedient. The district has been worked: recurrently for over 60 years. The Yoquivo province lies on the steep western-slope of the Tara-humara division of the Sierra Madre range of mountains. The province is traversed by many deep canyons, most of which flow west. The town is situated on the San Francisco arroyo, which makes a confluence with the Huevachic stream 212 m. southwest; the Huevachic in turn joins the Candemeña river farther down and these two drain the western flank of the Tarahumara mountains and form the headwaters of the Mayo river. The claims of the Yoquivo Development Co., which, is the only organization in the district with a record of any considerable production,: lie within an area roughly 112 m. square. The area extends from the, San Francisco arroyo north, and from the Dolores arroyo west, and is confined to the andesitc formation.

Jan 2, 1926

By Clarence P. Linville

It is recognized that, in all metallurgical operations, the greatest possible uniformity in all conditions is essential to the best results. It is the constant aim of metallurgists to secure this uniformity, and their success in this respect has been in many cases the cause of great advances in the metallurgical processes themselves. Of all such processes, the production of pig-iron in the modern blast-furnace is perhaps the most complex and the most difficult of control. Notwithstanding the great progress of recent years, there is still great difficulty in obtaining anything like uniform conditions and results in the manufacture of pig-iron. The reason is not far to seek. The ores vary in composition and physical properties, often carrying a varying amount of gangue material, unevenly distributed. The coke may vary in composition, cell-structure, moisture, hardness, and other properties. The blast, the weight of which far exceeds that of any other constituent, varies in its moisture-content and consequently in its chemical composition; and its temperature, by reason of the method of heating, is not uniform, but, besides varying from time to time with atmospheric and other outside conditions, has a maximum and minimum for every changing of stoves. Now, with regard to these variations, the modern demand for uniformity has been greatly aided. Chemical analysis has made it possible to select ores so that the composition of the charge can be kept fairly constant; coal may be obtained from a given field, and coked in the same kind of ovens under conditions which make the fuel practically uniform; the Gayley

Jan 1, 1911

By H. S. Hanna, C. Rampacek

The problems and limitations encountered in the Physical beneficiation of the Appalachian Red Iron Ores are discussed. Two major problems are identified - the high phosphorus content and the fine dissemination or encapsulation of mineral impurities in the iron-bearing minerals. A process that combined extreme fine grinding techniques with magnetizing roasting or flotation-separation methods is suggested. By these methods, concentrates assaying 60-61 % Fe, exceeding the widely accepted upper limit of 56% Fe set for these ores, were produced with 75-90% iron recovery. Moreover, it was shown that the phosphorus content of these concentrates could be reduced from 0.25% to 0.03% phosphorus by acid leaching. A brief discussion on production costs based on current and future developments in iron ore processing is given.

Jan 1, 1983

By C. A. Heberlein

INTRODUCTION THE present war in Europe seems to have stimulated the demand for quicksilver. In July last, the price ranged around $35 per flask of 75 lb., while to-day it seems to fluctuate between $47.50 and $50. The use of quicksilver in the form of fulminate, containing 70 per cent., and as corrosive sublimate, containing 73.8 per cent., must be extensive and a further market advance may be expected. With such an advance, some revival in quicksilver mining maybe looked for, particularly in California, where many abandoned properties exist. What can be done with low-grade quicksilver ores under favorable conditions, particularly with low mining cost, may be seen from the following description of the Oceanic mine, near. San Luis Obispo, Cal. Its operations date back to 1876, when rich sand ores were discovered. In three years 7,400 flasks of quick-silver were produced, but since then the deposit has been only sporadically worked. Until two years ago various attempts had been made by the Oceanic Quicksilver Co. to mine the more refractory "mud rock," which was encountered lying beyond the "sand rock." Mud and sand rock in varying quantities were treated together with poor results, but operations were successful with sand rock of fair percentage. About two years ago,, when all the sand rock had been exhausted, Murray Innes purchased the Oceanic mine. He found large quantities of low-grade mud rock, varying from 6 to 8 lb. of quicksilver per ton, which at the prevailing low price of quick-silver demanded very cheap mining costs, in conjunction with high but cheap metallurgical extraction. At that time the extraction of quicksilver from mud rock ranged between 40 and 50 per cent., as far as I am able to, learn.

Jan 2, 1915

By James B. Cathcart

Marine phosphorite deposits occur in Braxil, in the Bambui Group of late Precambrian or Early Cambrian age. The phosphorite is laminated, isoclinally folded, and is composed of black, elongated apatite pellets and quartz grains cemented by quartz and muscovite. Abundant, narrow quartz veinlets cut through the .rock at right angles to the elongation direction of the pellets. The phosphorite is 0 to 80 m thick and contains 5 to 30 percent P2O5. The deposit is elongate towards the northeast, and the central, thickest, and richest part is bounded by faults. Measured reserves are about 250 million tons that average a bout 13 % P205. Preliminary testing indicates that grinding, scrubbing, and desliming will produce a material usable for fertilizer manufacture at a cost competitive with imported phosphate fertilizers.

Jan 1, 1979

By Edward Estabrook

THE Salt Creek oil field in Natrona County, Wyo., is the largest pool that has been found in the Rocky Mountain region and one of the largest in the United States. Many features of its production records are of peculiar interest, because of the unusual slowness with which it has been developed. This paper is published by the permission of the Midwest Refining Co., whose records have been freely drawn upon. Many mem¬bers of the Midwest organization have assisted in the collection of the material, but Messrs. F. E. Wood and L. E. Smith have been particularly helpful. The Salt Creek oil field is situated on a great dome with a closure of about 1500 ft., which rises at the northern end of a long anticline extending north-northwest by south-southeast for fully 25 miles. The productive area includes parts of townships 39 and 40 north and ranges 78 and 79 west of the sixth principal meridian. The Teapot oil field occupies a minor dome at about the center of the same anticline and adjoins the Salt Creek oil field on the southeast. The Teapot Naval Reserve includes the Teapot Dome and about 760 acres of the Salt Creek dome. In this paper, the Salt Creek oil field will be considered as' including all of the dome, except that part which lies within the Teapot Naval Reserve and the area west of the dome where oil is produced from shale crevices.

Jan 9, 1925