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By Dave H. Barnett, Brij M. Moudgil

The flotation technique as employed by Florida phosphate producing companies for the beneficiation of fine phosphate particles has been standardized over the years. Lower recoveries of coarse Phosphate rock by froth flotation technique, however, led to the development of new methods based on skin flotation of phosphate agglomerates. Recent developments of floating coarse rock in large flotation machines have not yet convinced the rock Producers of their higher separation efficiency. It is interesting to note that the selection of a particular machine is still bared on equipment preference by an individual company as well as proven performance of a particular machine for upgrading a specific material. Various techniques which have been developed to beneficiate the coarse phosphate rock have been discussed. Performance of the individual techniques is presented.

Jan 3, 1979

By H. S. Munroe

AN elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics.* In a subsequent report- was printed a paper, by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cant and tappet stamps commonly used in the West. The atmospheric stamp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation : "In considering the economical application of stamping machinery, we meet, at- the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such * Mineral Resources West of the Rocky Mountains, 1871, p. 380. †- Mineral Resources West of the Rocky Mountains,, 1873, p. 345.

Jan 1, 1881

By Donald Markle

ANTHRACOAL is a mixture of small particles of anthracite coal and a matrix of practically pure carbon, formed from the distillation of coal-tar pitch or other suitable bitumen. It is a hard, dense, homogeneous mass, with a silvery luster and in color varies from silvery to grayish black. When pushed from the oven, it develops only partly the fingerlike structure of coke; but, unlike coke, it has a tendency to remain in blocky masses. When struck with a hammer or passed through crushing rolls, it breaks with an irregular fracture, similar to anthracite, but with very little fines. Due to its density, anthracoal is harder, tougher, and stronger than coke. The results of a test made by the blast-furnace department, of the Bethlehem Steel Co., on two barrels of anthracoal are given in Table 1. TABLE I.-Results of Shatter Tests on Anthracoal and Coke Anthracoal Test Good Blast-furnace Coke First Second Barrel Barrel Moisture, per cent 0.77 0.76 Under 5, variation not over 3 points Sieve test Through 2-in. screen, per cent 7.71 7.29 Under 40 Through 1-in. screen, per cent 1.37 1.56 Through ½ -in. screen, percent 0.93 1.08 Under 8 Over 2-in. screen, per cent 92.29 92.71 Over 60 Shatter test Through 2-in. screen, per cent 10.06 ' 12.40 1 Under 16 Through 1-in. screen, per cent 2.66 2.06 Through ½ -in. screen, per cent 1.80 1.26 Over 2-in. screen, per cent Hardness number 86.40 86.10 Over 81 Analysis Ash, percent 16.64 16.48 Under 11 Sulfur, per cent 1.17 1.10 Under 0.95 Volatile matter, per cent 0.77 0.27 Fixed carbon, percent 82.59 83.25 Over 87

Jan 8, 1921

By Masayuje Otagawa

The mining methods adopted in Japanese mines are less known to the mining world than those of other countries, owing to the geographical remoteness, but they present many features of interest to mining engineers. The Ashio copper mine is at the town of Ashio, in Tochigiken, about 109 mi. (175 km.) from Tokyo by the Imperial Government railroad. The area of the concession owned by the Furukawa Mining Co. is 5000 acres (5023 ha.). The mine was formerly divided into three, viz. Hon-ean, Kotaki, and Tsudo, which are distant 3 mi. (4.8 km.) from each other as shown in Fig. 1. However, in 1914, when the writer was general manager, the three mining plants were amalgamated into one with the result of simplifying the working projects and increasing the operating efficiency. The mine was visited by the Institute party in November, 1911, when K. Inouye was the general manager. Shortly afterward, the writer was appointed manager, and, in 1915, he was succeeded by Dr. K. Asano. At the end of 1917, K. Kibe became general manager and, after two years, was succeeded by the present manager, I. Sugimoto. For some time Dr. J. Kojima was acting general manager. It is necdless to say that the gentlemen mentioned are all members of the Institute, as is also Baron T. Furukawa, president of the company. Since the discovery of the enormous masses, called "kajika" or "bullhead" deposits, which the writer has described elsewhere,' the mining methods have been varied to meet the different conditions presented by these deposits. The Ashio Ore The country rock of this mine consists of the middle Chichibian slate and quartzite into which has been intruded a post-Tertiary plagio-liparite neck more than 2 mi. in diameter, in the shape of an inverted cone which narrows downward to a relatively small diameter in depth.

Jan 1, 1923

By Masayuje Otagawa

The mining methods adopted in Japanese mines are less known to the mining world than those of other countries, owing to the geographical remoteness, but they present many features of interest to mining engineers. The Ashio copper mine is at the town of Ashio, in Tochigiken, about 109 mi. (175 km.) from Tokyo by the Imperial Government railroad. The area of the concession owned by the Furukawa Mining Co. is 5000 acres (5023 ha.). The mine was formerly divided into three, viz. Hon-ean, Kotaki, and Tsudo, which are distant 3 mi. (4.8 km.) from each other as shown in Fig. 1. However, in 1914, when the writer was general manager, the three mining plants were amalgamated into one with the result of simplifying the working projects and increasing the operating efficiency. The mine was visited by the Institute party in November, 1911, when K. Inouye was the general manager. Shortly afterward, the writer was appointed manager, and, in 1915, he was succeeded by Dr. K. Asano. At the end of 1917, K. Kibe became general manager and, after two years, was succeeded by the present manager, I. Sugimoto. For some time Dr. J. Kojima was acting general manager. It is necdless to say that the gentlemen mentioned are all members of the Institute, as is also Baron T. Furukawa, president of the company. Since the discovery of the enormous masses, called "kajika" or "bullhead" deposits, which the writer has described elsewhere,' the mining methods have been varied to meet the different conditions presented by these deposits. The Ashio Ore The country rock of this mine consists of the middle Chichibian slate and quartzite into which has been intruded a post-Tertiary plagio-liparite neck more than 2 mi. in diameter, in the shape of an inverted cone which narrows downward to a relatively small diameter in depth.

Jan 1, 1923

By Carle Hayward

SULPHUR has long been one of the banes of the steel manufacturer and often no effort and expense have been spared in order to reduce it to a small per cent. in the finished product. This condition is clue to a general conviction that in many cases where steels have failed in service, sulphur has been the cause. But there has been a growing feeling in recent years that the verdict against sulphur has been unnecessarily severe. In cases of segregation it was present in augmented amounts along with other impurities, but it had not caused the segregation. High sulphur in pig iron is caused by poor furnace conditions and the sulphur is merely one indication of an iron that has not been properly reduced. No amount of subsequent treatment under oxidizing conditions in the open-hearth furnace can remedy the defects, although the per cent. of sulphur may be considerably reduced. In other words, the causes of bad steel can frequently be traced back to bad pig iron, and sulphur is merely one indication that the pig iron is bad. The writer recently visited a steel plant where a mass of evidence had been accumulated which substantiated this fact, and the superintendent was .emphatic in stating that high sulphur was not harmful provided the steel was not otherwise poor due to insufficient reduction in the blast furnace. The presence of a moderate amount of sulphur is desirable from the standpoint of the man who machines the steel. The low-sulphur material drags and the production of a smooth surface is very difficult. A slight increase in sulphur enables the machinist to produce a smooth surface without difficulty. Since, therefore, such large quantities of steel are subjected to machining, it becomes highly important that the sulphur controversy should be settled, and if its presence is proved to be harmless the ban on it should be lifted.

Jan 10, 1916

By S. K. Bradford

(Pittsburg Meeting, March, 1910.) FOR years past I have traveled in quest of promising mining-properties, over almost impassable mountain-trails to remote places in the mining-regions, usually, many miles from an assay-office. If, upon examination, the formation and the ore-deposit appeared favorable, a quick determination of the value of my samples was necessary, in order that I might take intelligent action with reference to the acquisition of the property. A journey with my samples to civilized regions often meant weeks of delay, and perhaps loss of opportunity. How many, under similar circumstances, have returned with their assay-results from such a journey, only to find that some audacious speculator had " optioned" the property ! True, a first payment could have been made and the chances taken on the results; but experience has taught that rich-looking ore is not of necessity valuable. Personally, I would not hazard a ten-dollar bill on any property without first determining by assay the value of the ore. To carry the usual complete assay-paraphernalia over such mountain-trails was impracticable by reason of the loss of time involved, the great expense of transportation (charged according to weight), and the fact that a few such trips would almost certainly wreck the outfit. For these reasons I began a process of elimination and substitution which finally enabled me to carry, in an ordinary 26-in. valise, sufficient apparatus and supplies for, say, 100 assays of adequate commercial accuracy. My final outfit was as follows: APPARATUS. Small hammer; steel mortar (2.5 in. wide, 3 in. high, with stand sawed off flat, so that it can be used as an anvil and for

Jan 1, 1911

By J. Fred Johnson

MORE ORE is mined in the Bingham District than in any other mining district in Utah. In addition to the open-pit operations of the Utah Copper Co., there have been, many large underground mines. Until recent years the principal production was from the Jordan and Commercial limestones, but in the last eight years valuable ore deposits have been developed in the so-called alphabetical or "A," "B," "C," and "D" limestones, mainly by the U. S. Smelting, Refining & Mining Co. The value of these developments has led the company just mentioned to acquire large holdings in the district and within the last year to install at the Niagara shaft a hoist capable of going to a vertical depth of 4000 ft., or 1800 ft. deeper than the present lowest level. Ore from Bingham has been the chief factor in enabling the

Jan 1, 1934

By Kenneth R. Hancock

Iron oxides are unique in that they are the only significant colored mineral found in a natural state suitable for use as a pigment after being pulverized to pigmentary size. The current world production of iron oxide pigments is estimated by the author to be between 499 and 590 kt (550,000 and 650,000 st) based on 1979 data. The fact that highly colored natural deposits of iron ore are found throughout the world accounts for its use in prehistoric man's artistic cave paintings. These early artists did not realize that they had established man's first paint test fence which now has some 20,000 years of exposure. In addition to abundance, constituting about 7 % of the earth's crust, iron oxides have the advantages of low cost, permanency, and are not toxic. Through the centuries, succeeding civilizations have utilized iron oxides as a major source for decoration and protection when coloring was desired. In the last century the chemical industry has improved on nature by developing a complete range of synthetic iron oxide pigments which surpass the pigments produced from natural iron ores in uniformity, color quality, and chemical purity. In the United States alone, the combined production of natural and synthetic iron oxides produced sales of over $28,000,000 in 1970 (Stipp, 1970) and increasing to $97 million by 1980 (Spinrad, 1980). Nomenclature With the increasing importance of the synthetic iron oxides it is necessary to make a distinction between the natural or mineral pigments and the synthetic pigments. Natural pigments are those products which are derived from selected ores and should not be confused with iron ores mined for steel production. Iron ores that are mined for steel must be capable of being mined and reduced to iron on a commercial basis. These ores are selected on the basis of iron content and processing economics. It is therefore unusual when iron ores for steel production are suitable for use as mineral pigments. Natural pigment ore sources are selected for their special physical-chemical properties and can command a premium price. Synthetic pigments, and in this instance iron oxides, are those pigments produced from basic chemicals. Through chemical synthesis pigmentary sized particles are produced as opposed to comminution, the major procedure common to all natural iron oxide pigments. Classification An important characteristic of a pigment is its color and, therefore, a logical separation can be made on this basis. A. Yellow Iron Oxide Pigments 1. Natural mineral origin a) Goethite b) Lepidocrocite c) Ochres d) Siennas e) Limonite 2. Synthetic pigments a) Goethite B. Red Iron Oxide Pigments 1. Natural mineral origin a) Hematite b) Siderite (calcined) c) Pyrites (calcined) 2. Synthetic pigments a) Hematite C. Brown Iron Oxide Pigments 1. Natural mineral origin a) Umbers b) Limonite (calcined) c) Siderite (calcined) d) Goethite (bog ore or sulfur mud) 2. Synthetic pigments a) Blends of hematite, goethite, and magnetite

Jan 1, 1983

By David T. Day

In the summer of 1898, a demand suddenly arose for commercial quantities of the element osmium. At least half a ton was wanted for the manufacture of a new incandescent light. This led the writer to examine localities where platinum had been reported, in order to determine whether osmiridium mas contained in the crude platinum. With the co-operation of the concern most interested, the Welsbach Light Company, and in company with its President, Col. William E. Barrows, I visited most of the leading American localities where platinum has been obtained. I also wrote to every available placer-mine in the West for samples of the heaviest sands, in order to test them for platinum. The results of this inquiry are given in the present paper. Distribution. The notices of the occurrence of platinum in this country given in scientific journals include two interesting observa tions in the East. One concerns a nugget described by Peter Collier of Washington, D. C.,* and said to have been found on land adjacent to the village of Plattsburgh, N. Y., which weighed 104.4 grammes, and contained sufficient chromite to reduce the specific gravity from 17.35 for the heaviest portion to

Jan 1, 1901

By T. Sterry Hunt

BUT little was known of the coals of Southeastern Ohio until the present survey of the State under Dr. Newberry began its work. The results of the geological investigations of Prof. E. B. Andrews in this region, and of the chemical investigations of Prof. T. G. Wormley, both of which appear in the reports of the survey for 1869 and 1874, and more recent special reports by the former, together with some data for which I am indebted to the kindness of Dr. Newberry, and my own limited observations, have served me for the preparation of the following notice of the coals lying on the western border of the great Appalachian coal-basin in the region drained by the Hocking River and its tributaries, and belonging to the Lower Coal-Measures. Some uncertainty exists as to the place in the succession of the lower coals to be assigned to the seams known and mined in the Hocking Valley. It is the opinion of Prof. Andrews that the inequalities of the original surface were such that we cannot identify in that region the lowest coals known in Northwestern Pennsylvania and the contiguous parts of Ohio, but that we must rather count from above downwards. These conclusions Dr. Newberry is not prepared to accept, and further researches will be necessary before certainty can be attained in this matter. Meanwhile it seems, from a study of its relations to the Pomeroy or Pittsburgh seam, that what is known as the great vein of the Hocking Valley, occupies the horizon of the Upper Freeport coal, E of the Pennsylvania survey, or No. 6 in Dr. Newberry's enumeration, counting from the base. This seam, in the region in question. assumes certain characteristics which, taken in connection with its geographical position, give it a great importance among the coals of the State. The area to be noticed includes the whole or parts of several townships in Perry, Hocking, Vinton, and Athens Counties, lying near the margin of the basin over which the vein in question assumes the character of a dry-burning or splint coal, and has a thickness varying from six to ten and even twelve feet. Its precise limit southward cannot at present be clearly defined, but it has been found as far south as the line of the Marietta and Cincinnati Railroad, with a thickness of six feet, and is mined at various points along the valley of the Hocking River, near Nelsonville, where it attains six or seven feet. To the northward, along the tributaries of this river, Sunday and Monday

Jan 1, 1874

By T. Sterry Hunt

But little was known of the coals of Southeastern Ohio until the present survey of the State under Dr. Newberry began its work. The results of the geological investigations of Prof. E. B. Andrews in this region, and of the chemical investigations of Prof. T. G. Wormley, both of which appear in the reports of the survey for 1869 and 1874, and more recent special reports by the former, together with some data for which I am indebted to the kindness of Dr. Newberry, and my own limited observations, have served me for the preparation of the following notice of the coals lying on the western border of the great Appalachian coal-basin in the region drained by the Hocking River and its tributaries, and belonging to the Lower Coal-Measures. Some uncertainty exists as to the place in the suc- ' cession of the lower coals to be assigned to the seams known and mined in the Hocking Valley. It is the opinion of Prof. Andrews that the inequalities of the original surface were such that we cannot identify in that region the lowest coals known in Northwestern Pennsylvania and the contiguous parts of Ohio, but that we must rather count from above downwards. These conclusions Dr. Newberry is not prepared to accept, and further researches will be necessary before certainty can be attained in this matter. Meanwhile it seems, from a study of its relations to the Pomeroy or Pittsburgh seam, that what is known as the great vein of the Hocking Valley, occupies the horizon of the Upper Freeport coal, E of the Pennsylvania survey, or No. 6 in Dr. Newberry's enumeration, counting from the base. This seam, in the region in question. assumes certain characteristics which, taken in connection with its geographical position, give it a great importance among the coals of the State. The area to be noticed includes the whole or parts of several townships in Perry, Hocking, Vinton, and Athens Counties, lying near the margin of the basin over which the vein in question assumes the character of a dry-burning or splint coal, and has a thickness varying from six to ten and even twelve feet. Its precise limit southward cannot at present be clearly defined, but it has been found as far south as the line of the Marietta and Cincinnati Railroad, with a thickness of six feet, and is mined at various points along the valley of the Hocking River, near Nelsonville, where it attains six or seven feet. To the northward, along the tributaries of this river, Sunday and Monday

By J. M. Callow

H. A. MEGRAW, New York, N.,Y.-One interesting thing that might be brought out in this connection is the cost of making sulphide gas. I had a communication the other day which suggested that, in view of the high cost of oil, sulphur and sodium sulphide, we might make use of a well-known chemical reaction to form this sulphide gas by the use of aluminum sulphide. It is difficult to see any advantage in this, however, since aluminum has been affected just as much as any other commodity by the rise in prices, due, to war conditions. RUDOLF GAHL, Miami, Ariz. (communication td the Secretary*) Mr. Callow refers to my paper, History of Flotation at Inspiration, which was presented at the Arizona meeting of the Institute. These notes of Mr. Callow's contain much valuable information on flotation practice, as is to be expected from an article written by an author of Mr. Callow's experience in this branch of metallurgy. Nevertheless, I cannot help contradicting a number of the statements made in the references to my paper. In passing, I will also say a word about the reference in Mr. Callow's paper to the article by Messrs. Laist and Wiggin entitled "Flotation Concentration at Anaconda, Mont." Mr. Callow calls attention to the fact that evidently Callow flotation machines are not very sensitive, inasmuch as one man per shift handles four 800-ton sections of Callow machines or 3,200 tons per day at the Inspiration plant. While-it has been the experience of the Inspiration company that the four sections of Callow machines in the Inspiration concentrator are easily handled by one American operator per shift, it is only fair to state that each man operating four sections is assisted by two Mexican helpers who constantly clean the bottoms of the machines. The tonnage per section, by the way, whether equipped with Callow,, Inspiration or Minerals Separation machines, is considerably in excess 4 800 tons.. Mr. Callow further says that local opinion at Inspiration is that, two 800-ton sections consisting of two 10-compartment and four 6-compartment Minerals Separation machines (these machines are of the Hebbard type) is the limit that one man can properly attend. I do not hesitate to say that I consider it perfectly feasible to have four such sections operated by one man, perhaps assisted by "one helper. The Minerals Separation machines of this type have undoubtedly an advantage as far as easiness of operation is concerned,

Jan 4, 1917

By A. A. Mathews

During the past year (1967-68), there have been many instances of either partial or complete failure of a tunnel-support system. It looks like the art is in a pretty sad state, but as long as we permit the field of tunnel design to remain basically an art, that's about what we can expect. The application of scientific principles to tunnel design involves much more than assigning values to a series of factors in an equation. I am reminded of the case where the engineer calculated that steel ribs with struts were required to support a horseshoe-shaped tunnel in firm ground. The contractor had driven several hundred feet without installing the struts when the engineer visited the job. When he was informed that the struts had been left out, he fled the tunnel in alarm. As one authority has so aptly put it, "There is far too much calculating and too little observing." Initially, one might think of a tunnel support as a structural member, such as a strut or arch which is installed in order to support some definite load. Similarly, a tunnel lining might be considered as a treatment of the interior surface of the tunnel in order to produce desired aesthetic, hydraulic, or architectural results, or to serve a protective function. Actually, many linings, such as a concrete lining, serve a dual purpose and support a load as well as satisfy other requirements. Not too many years ago a tunnel, during the driving or excavating stage, was considered to be either supported or unsupported. In recent years, however, several techniques have been developed, which by helping the tunnel to support itself, permit the elimination of separate structural support. Since these techniques in many cases actually become a substitute for the conventional types of supports and linings, a state-of-the-art review would hardly be complete without including them for consideration. Thus, for the purpose of this discussion, we shall define tunnel supports as any system or technique which effectively maintains the integrity of the tunnel opening. In their chapters, both Jacobs (No. 6) and Lippold (No. 7) pointed out how support systems have advanced from timber supports to steel supports

Jan 1, 1970

By AIME

AS the Petroleum Division rounds off the first quarter century since its evolution from technical committee status, there steps to the long line of notable men who have presided over its activities a young man, currently of Tulsa, one Herbert F. Beardmore by name. For one year, as Chairman for 1946, the Division will be his oyster. hi; baby, his responsibility. "Herb" Beardmore was born at Columbus, Ohio, Feb. 6, 1904, and lived there until he was thirteen. Then his family moved to Oklahoma City, and later sent him to the University of Oklahoma, where he graduated in 1925 with a B.S. in engineering geology. His final year in college was the first year in which a petroleum engineering course was taught at the school. Since his course of study so closely paralleled that of a petroleum engineer, he has frequently been spoken of as the first petroleum engineering graduate from the University of Oklahoma. Out of college he went to work as an oil-field roustabout in the Ranger, Texas, field for Jake L. Hamon. This work consisted of all manual labor phases of cable-tool operation and beam-pumping of oil wells. He moved in 1926 to Bartlesville, to become a gas engineer for the Indian Territory Illuminating Oil Co., where he was employed in gas-well drilling, gas production, and transportation, mostly in Osage County, Oklahoma.

Jan 1, 1946

Jan 1, 1913

By A. C. JR. Boyle

I. INTRODUCTION THE geological field work of the Bully Hill district, upon which this paper is based, was begun July 1, 1908, and covered a period of three months. The time was found too short for a complete report and the district was again visited in the early part of July, 1912,. from which time detailed study of the locality continued until September of the same year. This paper is the result of observations made in the mines in the immediate vicinity of Winthrop, Shasta county, Cal., during these two periods of study. The preparation of this report has been greatly facilitated by various courtesies rendered the writer by D. M. Riordan, President of the Bully Hill Copper Mining & Smelting Co., and by John B. Keating and Herbert R. Hanley, managing officers actively in charge at the mines. The elaboration and further study of the notes and collections were carried on in the laboratories of the Departments of Geology and Mining at Columbia University, and the writer takes pleasure also at this point in expressing his acknowledgments to Profs. James F. Kemp, A. W. Grabau, Charles P. Berkey, and William Campbell, for advice and assistance. In order that one may appreciate at first reading the significance of some of the details which follow, and for the sake of clearness, a brief outline of the geological relationships is here given, together with certain conclusions which have been reached regarding the genesis. of the ores and the gypsum masses. In the Bully Hill mining district an associated series of Triassic lavas and tuffs, chiefly andesites, is preceded as well as followed by sediments. The entire system is tilted so that the original bedding planes dip in general to the southeast. The surrounding region has been greatly disturbed, and in the immediate vicinity of the mines close folding of the later sediments and extreme shearing of the igneous rocks locally is a striking feature. Into the nearly vertical shear zones have been intruded post-Triassic dikes of various rock types in the following order: alaskite-porphyry and andesite-porphyry. Outside the area under consideration diorite dikes are known, but they will not receive attention further than to note that' they, probably, represent a differentiation product of the same magma from which the other two dikes came. In this connection all the dikes have an important bearing on the origin of the ores and of the gypsum found in the mines.

Jan 1, 1914

By Louis D. Huntoon

The Porcupine gold area, located on the Hudson Bay slope of northern Ontario, has produced over $100,000,000 in gold and has paid more than $28,000,000 in dividends, since the first real production in 1912. The character of the ore has been studied by the geologists of the Bureau of Mines of Ontario, the geological staffs of the operating mines, and engineers commissioned to examine properties there. What information the Government has is free to everybody; the geological staffs of the several properties also give to the visiting engineer what information regarding ore deposition they possess, and the author wishes to express his indebtedness to the geologists of the Ontario Bureau of Mines and the staffs of the operating mines for their free discussion of geological questions. This paper is based on the examination of several properties, various petrographic reports, not only on specimens from Porcupine but from elsewhere in northern Ontario, and interviews with Government and mine staff geologists. The petrographic work has been done by Prof. R. J. Colony, of Columbia University. Geological History The geological history of the district may be summarized as follows: The outpouring of great floods of lava accompanied by beds of tuff, flow following flow; the contacts of different flows can be seen in various parts of the camp. This period mas followed by an uplift and the production of the Temiskaming sediments by erosion. Later, dynamic action turned the sediments and underlying lavas on edge; this was followed by the intrusion of igneous rocks—in the Porcupine area the quartz porphyry, which is of such great importance in connection with the gold deposits. Doctor Burrows says: "The intrusions of quartz porphyry have in some way influenced the deposition or location of the gold but it is not likely the porphyry has been the source of the gold-bearing solutions." This statement of Doctor Burrows I indorse. The formation of non-gold bearing quartz veins followed the intrusion of the porphyry. These veins occur along or near the contact of

Jan 1, 1923

By Louis D. Huntoon

The Porcupine gold area, located on the Hudson Bay slope of northern Ontario, has produced over $100,000,000 in gold and has paid more than $28,000,000 in dividends, since the first real production in 1912. The character of the ore has been studied by the geologists of the Bureau of Mines of Ontario, the geological staffs of the operating mines, and engineers commissioned to examine properties there. What information the Government has is free to everybody; the geological staffs of the several properties also give to the visiting engineer what information regarding ore deposition they possess, and the author wishes to express his indebtedness to the geologists of the Ontario Bureau of Mines and the staffs of the operating mines for their free discussion of geological questions. This paper is based on the examination of several properties, various petrographic reports, not only on specimens from Porcupine but from elsewhere in northern Ontario, and interviews with Government and mine staff geologists. The petrographic work has been done by Prof. R. J. Colony, of Columbia University. Geological History The geological history of the district may be summarized as follows: The outpouring of great floods of lava accompanied by beds of tuff, flow following flow; the contacts of different flows can be seen in various parts of the camp. This period mas followed by an uplift and the production of the Temiskaming sediments by erosion. Later, dynamic action turned the sediments and underlying lavas on edge; this was followed by the intrusion of igneous rocks—in the Porcupine area the quartz porphyry, which is of such great importance in connection with the gold deposits. Doctor Burrows says: "The intrusions of quartz porphyry have in some way influenced the deposition or location of the gold but it is not likely the porphyry has been the source of the gold-bearing solutions." This statement of Doctor Burrows I indorse. The formation of non-gold bearing quartz veins followed the intrusion of the porphyry. These veins occur along or near the contact of

Jan 1, 1923

By B. Wilshire, W. J. Evans

W. J. Evans and 8. Wilshire SEVERAL recent investigations1-6 have shown that the strain, c, during transient and steady-state creep is well-represented by the expression: € = e0 + et(l - e-mt) + Esl [l] where Eo is the instantaneous strain on loading, ET the total transient strain, C, the steady creep rate! and m a constant relating to the rate of exhaustion of transient creep. However, it has been noted6 that deviations from this equation occur over the first 10 to 15 pct of the transient stage, when the creep rate, (. decreases more rapidly than is predicted by this equation. This rapid decrease has been attributed to a large change in work-hardening coefficient. It 1s widely accepted that steady-state creep results from a balance between the rate of strain hardcning h and the rate of recovery r (=-s(st) as: dE/dt = Es = r/h [2] Comparison of values obtained for h at the end of the initial extension and during steady creep suggests that h increases several fold during the transient stage. which has the effect of reducing the creep rate proportionally.7 To examine the dependence, on r and h, of the deformation behavior during transient and steady-state creep. a series of constant-stress creep tests was carried out at 413°C at 6000 psi using 70-30 a brass. Prelinlinary investigation showed that. with this material. the transient stage constituted a significant portion of the total creep life (-0.4tf. where tf is the time to fracture). The alloy. obtained from Metals Research Limited. was made from high-purity copper, 99.999 pct. and zinc. 99.99 pct. Heat treatment at 675°C for 4 1/2 gave a uniform grain size of 5 mm-1. Details of specimen preparation and creep testing procedures have been given previously.6 Values of h (?s/?E) were determined by measuring the instantaneous strain. ?E. which occurred on increasing the stress during creep by a small amount. ?s. Similarly. v (= -?s/ ?t) was derived from the incubation period. At, after a small decrease in stress.' Several values of v and h were obtained throughout duplicate creep tests. using different stress increments in the range 300 to 800 psi. The accuracy with which Eq. [I] represents the present creep curves was established by determining the best value of the constants Es, Et, m , and 6, using a digital computer program based essentially on the graphical solution for this equation devised by Conway and Mullikan.9 About 40 strain/time readings were taken during transient and steady-state creep. Over most of the creep curve, the average difference between the measured reading and the calculated strain at the appropriate time was less than 0.0001. However.

Jan 1, 1969