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By S. F. Emmons

The history of the mining region of Custer county has been somewhat peculiar. Although, in the broader features of geological structure, it bears a strong resemblance to its newer and now more famous neighbor, 40 miles to the northward, the Cripple Creek mining district, it has been noted for failures rather than for successful mining ventures. Yet it has a number of mines that have proved themselves to be remarkably rich, and many others that have well-defined veins and very rich ore, though they never have been worked to any great depth. A few of the deposits seemed to the early miner so anomalous in form and manner of occurrence that they were popularly described as " contrary to all geological laws." The region has had several " booms," succeeded by more than usually violent reactions, the latter having proved more permanent than the former. It was, for a long time, the favorite resort of patent-process mongers, and the ground is now strewn with relics of various unsuccessful reduction-plants. Mismanagement, ignorance and disagreements among mine-owners seem to have been quite as responsible for the want of success in the region as the quality of the ores or the form of the deposits. In the early eighties, when the booms had not entirely died out, a division, then under my charge, of the U. S. Geological Survey, undertook an examination of the region for the purpose of making a study of its ore-deposits. The areal survey was carried to completion by Mr. Whitman Cross, but the study of the mines could never be completed for the reason that most of them were closed, for one reason or another, before we had time to visit them. From time to time, one or another of the important mines has been started up again, but it was not

Jan 1, 1897

By H. E. Nold

THIS paper is an effort to explain in a simple manner the fundamental principles involved in examining a clay deposit for both quantity and quality and in operating a clay mine, either open-pit or underground, so that the best quality of finished material can be made from the raw material available. The writer is aware that what is recommended in this paper is everyday practice in many refractories plants and in some other heavy-clay products plants, but observations made while visiting practically every clay mine in Ohio have convinced him that the practices herein discussed are not as widely used as their importance warrants. It is true that the problem of mining for quality is more acute in refractories plants than in most heavy-clay products plants, yet some of the latter are finding it profitable to pay more than ordinary attention to the selection and blending of their raw materials. It is hoped that this short paper may prove helpful to some who are now finding it difficult to produce a uniform product of as high quality as their clay deposit seems to warrant. The coordination of the work of the clay mine or pit with the manufacturing plant, to the end that the best product possible be made from the raw material available, presupposes a rather intimate knowledge of the clay deposit. The knowledge must include not only information of the amount of clay-available but also rather detailed information about both vertical and horizontal variations in quality of the clay. This information should cover three things: quality, quantity, and location.

Jan 1, 1929

By R. W. Raymond

The various modifications of the art of photography have become within the last few years the indispensable allies of every art and science. But, before the introduction of the process which is the subject of this paper, there was, so far as I am aware, no satisfactory means by which certain photographic negatives could be made to yield, without the intervention of the skilled draughtsman, electrotypes suitable for surface-printing. I refer to negatives taken from originals, such as natural objects, or or lithographs, in which the lights and shadows are not represented exclusively by lines and dots, such as can be photo-engraved. The greater usefulness to engineers and manufacturers of electrotypes as compared with lithographs is evident. The electrotypes can be kept indefinitely and used in the production of many thousand copies. They can be duplicated at trifling cost. They can be placed for printing together with the " forms " of type, or included in these, upon an ordinary press. Finally, they are cheap, when made mechanically from a suitable original. Various methods have been adopted for the preparation of such a secondary original (as it might be called) in cases where the first original is unsuitable for photo-engraving. Thus, for instance, portraits have been produced in electrotype from ordinary photographs as follows: A large negative is made of the original (say a carle de visite of a person deceased), and a proof taken, but not " fixed." Over this proof a skilled artist draws the portrait with a pen, producing a picture which resembles a line-engraving. The photographic proof, which has served merely to guide the artist, is now obliterated, and the pen-and-ink drawing is photo-engraved. Electrotypes thus produced often retain the likeness in a wonderful degree, and give spirited and satisfactory pictures. 1 may instance, as examples, which many will recollect, the portraits of our deceased members,

Jan 1, 1887

By E. De Goyler

Volcanic origin was among the first of the theories advanced to account for the occurrence of the salt domes of the Gulf coastal plain, northern Louisiana, and eastern Texas, and it is still being re-stated in various forms by the most recent contributors to our knowledge of the geology of such deposits. Argument has been largely by analogy and attention has repeatedly been called to the Mexican oil fields, particularly those of the Tampico-Tuxpam region, because of the occurrence of oil in close proximity to volcanic plugs in those fields, an occurrence supposed to have some resemblance to the common occurrence of oil in the salt domes of the United States. The author, having spent several months of the past year in a general study of salt domes and in a detailed study of certain domes in the United States, and having been acquainted for some time with the exploration of similar domes in the Isthmus of Tehuantepec region, Mexico, and with the general geology of the Tampico-Tuxpam region, Mexico, has reviewed the various theories of volcanic origin for salt domes which have been advanced to the present time. The purpose of this paper is to present such review and to discuss the supposed Mexican analogy. Review of Volcanic Theory R. Thomassyl who had visited the Five Islands of Louisiana between 1857 and 1859, in 1860 described them with some care, noting their distinct character, alignment, and similarity, and ascribing to them a volcanic origin. He regarded them as being akin to the mud lumps in the delta of the Mississippi and was impressed by their symmetry and by the ponds or lakes which occur on several of the islands and which he regarded

Jan 1, 1920

By Richard E. Chism

SAN DIMAS, in the State of Durango, Mexico, on the frontier of the State of Sinaloa, is the centre of an extensive and rich mining region, which has been exploited for over a hundred years; and the patio process for working silver ores has there attained the highest perfection of which it is capable. Local modifications have been engrafted upon the underlying principles of the process, but, as a whole, the San Dimas practice so fully illustrates its typical capabilities, that I have undertaken to describe its workings in the hope of lightening, to some degree, the labors of my professional brethren who may have occasion to visit Mexico." As is tolerably well known, the patio process, like all other systems of free amalgamation, is not successful with ores containing more than a trace of zinc or lead, the presence of zincblende being especially obnoxious. Iron and copper in small quantities are not particularly disadvantageous. The process succeeds very well with all sulphide ores which do not contain much more than a trace of arsenic and antimony, provided the tailings are concentrated, although, of course, it is best adapted for free milling ores. For suitable silver ores that contain small amounts of free gold the process is still a good one, but where the gold is combined with sulphurets, a considerable and even an excessive loss is inevitable. Hitherto the Mexicans have submitted to this loss, but, since the introduction of American mills, they are gradually abandoning the patio process in favor of the other. The San Dimas ores have a gangue of quartz and feldspar. They are composed principally of silver sulphides, with some chloride and

Jan 1, 1883

By F. Twyman, D. M. Smith

THOSE chemists (they are still greatly in the minority) who use the spectroscope, use it very often, and find it almost indispensable. As a means of detecting minute quantities of the metals it is unrivalled. A metal can be readily distinguished in the presence of any other element, compound, or mixture without the necessity of separation. The qualitative analysis of the metallic constituents of a substance, which the spectroscope gives so easily, is a sure basis for planning a chemical analysis. As the determination of each element proceeds the purity of precipitates may be checked as often as desired. If, possessing these advantages, the spectroscope has been neglected in general chemistry, it is not surprising that it was neglected in metallurgical chemistry; for many of the impurities which are of industrial interest, even when they are present in a metal or alloy in small quantities, are not then always easily detected by the examination of their visible spectrum. The history of the development of the art has been given in Bureau of Standards Scientific Paper No. 444.

Jan 1, 1928

By Marius R. Campbell

Does mine-sampling show the commercial value of a coal, and if so, how should it be done ? This question is often asked, but seldom answered. During the past summer, while engaged in securing coal for the Government coal-testing plant at St. Louis, I had an excellent opportunity to obtain information on t,his subject, and the results seem to furniih an answer to the question propounded above. Sampling for the U. 8. Geological Survey Coal- Testing Plant. In organizing the work of the testing-plant, it was decided that coal, in car-load lots only, would be accepted for testing; also that this coal should be loaded under the immediate supervision of a representative of the plant, so as to be certain that the car-load sample would be representative. As an additional check on the work, two mine-samples were to be collected from each mine visited, and these samples, as well as the sample from the car when it was received at the testing-plant, were to be carefully analyzed at the chemical laboratory established in connection with the plant and operated under the direction of Prof. N W. Lord of the Ohio State University, Columbus, Ohio. Mine-Samp1ing.—Mine-samples were collected with great care by me and my assistants, Messrs. J. Shober Burrows, John W. Groves and Frank W. De Wolf. The dominant idea in the regulations adopted for mine-sampling mas, that it should be done in such a manner that the sample would have the same composition as the commercial output of the mine.

Jan 1, 1906

By K. K. Kohli, S. S. Peng, R. E. Thill

Introduction Since the adoption of the Surface Mining Reclamation and Control Act of 1977, which mandates that surface subsidence be an intergral part of the underground coal mine design, there has been a sudden rise of demand on guidelines for minimizing surface subsidence and its associated structural damages. Unfortunately there is no sufficient amount of systematic subsidence data to fill such a gap, although considerable research has been devoted to the subsidence induced damages of surface structures in the past. However, it was said that many surface subsidence surveys have been performed and monitored by coal companies during the past twenty years, and that it will be a great source of information for subsidence engineering design if they can be collected and assembled together. An effort was therefore initiated in the Department of Mining Engineering, West Virginia University, under contract with the U. S. Bureau of Mines in December 1978 to contact each individual coal company in the Northern Appalachian Coal Field for any surface subsidence survey data. After 10 months' survey, the data collected include: 17 longwall panels and 2 room and pillar sections. The data in each panel and section cover the complete set of subsidence survey raw data, underground mine layout maps, surface topo maps, geological loggings showing the stratigraphic sequences and thickness of the overburden, and if available, locations and types of surface structures. On-site visits were followed to study the surface terraines and structures. Interviews were conducted with the owners of the surface structures in most cases about, if any, the history and characteristics of damages. Most subsidence surveys started with the first panel and ended with the second or sometimes, but rarely, the third panel. The first panel may be located in a virgin area but frequently it was adjacent to (on the tailentry side) a mined-out room and pillar section. It must be noted that all of the subsidence data is restricted only to the amount of vertical subsidence and that the horizontal displacement measurement was completely ignored. Primarily due to the fact that vertical subsidence is the most striking feature in a subsidence trough, which is mistakenly considered to be the only critical contributor to surface structural damages, and that a horizontal displacement survey is much more complicated and time-consuming.

Jan 1, 1981

By F. M. Lewis, J. F. Myers

The paper reports the development of a large, slow speed ball mill closed circuited with a hvdro-scillator. This increased grinding efficiency 28 pct over conventional units. AS the title indicates, this is a progress report for the first year of experimental operation of a relatively large diameter, slow speed ball mill with 1-in. balls, with and without various classifiers, and including a hydroscillator. Several years ago the authors came to the conclusion that if any further progress were to be made in our flotation process, an understanding of the chemical and physical reactions and the control thereof, in the grinding circuit, was essential. It may be stated, at this point, that the preparation of a correct feed for the flotation process is still the number one objective of our grinding studies. This progress report deals with grinding "per se," and not with the chemical and physical reactions as the result of grinding. Prior to this time we had taken the naive position, that since grinding had been practiced by the industry for some fifty years or more, it had been well exploited and developed by a host of investigators. Consequently, we had given the matter only superficial attention. At the start of our study, we were aware of the fact that some difference in opinion existed, but we were not prepared for the controversial evidence that developed nor for the extent to which the experts differed in their viewpoints. There seemed nothing else to do but to tour the continent and decide for ourselves what was right and what was wrong, read all the published literature and visit with anyone who had ideas about the matter. This we did over the next few ensuing years. Since our study has met with some measure of success, we report, herewith, these data that ultimately they may be of help to other investigators. In 1944 it became necessary to increase our grinding capacity and at the same time to grind the sulphide portion a little finer. This provided the impetus to put our ideas into effect. As has been previously described, our grinding flowsheet at that time consisted of a 6x12 rod mill, followed by two 5x10 ft, and one 6x12 ft trunnion overflow ball mills, with conventional rake classifiers. Naturally, we first considered all the possibilities of altering or adding to the existing equipment. It became evident that if any appreciable increase in grinding efficiency could be obtained, it would pay to scrap the existing small mills and classifiers and install one big mill with adequate classification. Trying to determine just how much more efficient a big mill could be, in which were incorporated all

Jan 1, 1951

By J. F. Myers, F. M. Lewis

The paper reports the development of a large, slow speed ball mill closed circuited with a hvdro-scillator. This increased grinding efficiency 28 pct over conventional units. AS the title indicates, this is a progress report for the first year of experimental operation of a relatively large diameter, slow speed ball mill with 1-in. balls, with and without various classifiers, and including a hydroscillator. Several years ago the authors came to the conclusion that if any further progress were to be made in our flotation process, an understanding of the chemical and physical reactions and the control thereof, in the grinding circuit, was essential. It may be stated, at this point, that the preparation of a correct feed for the flotation process is still the number one objective of our grinding studies. This progress report deals with grinding "per se," and not with the chemical and physical reactions as the result of grinding. Prior to this time we had taken the naive position, that since grinding had been practiced by the industry for some fifty years or more, it had been well exploited and developed by a host of investigators. Consequently, we had given the matter only superficial attention. At the start of our study, we were aware of the fact that some difference in opinion existed, but we were not prepared for the controversial evidence that developed nor for the extent to which the experts differed in their viewpoints. There seemed nothing else to do but to tour the continent and decide for ourselves what was right and what was wrong, read all the published literature and visit with anyone who had ideas about the matter. This we did over the next few ensuing years. Since our study has met with some measure of success, we report, herewith, these data that ultimately they may be of help to other investigators. In 1944 it became necessary to increase our grinding capacity and at the same time to grind the sulphide portion a little finer. This provided the impetus to put our ideas into effect. As has been previously described, our grinding flowsheet at that time consisted of a 6x12 rod mill, followed by two 5x10 ft, and one 6x12 ft trunnion overflow ball mills, with conventional rake classifiers. Naturally, we first considered all the possibilities of altering or adding to the existing equipment. It became evident that if any appreciable increase in grinding efficiency could be obtained, it would pay to scrap the existing small mills and classifiers and install one big mill with adequate classification. Trying to determine just how much more efficient a big mill could be, in which were incorporated all

Jan 1, 1951

By J. N. Roberts, K. V. Gow

In a recent review of the field of plastic deforrnation of metal single crystals, Maddin and chenl indicated the need for systematic investigations of the crystallography of the slip process with special attention to: a) The effect of the orientation of a crystal on the appearance of slip lines, b) The effect of high temperatures on the slip systems of aluminum, c) The effect of strain rate on the crystallography of slip. The present paper deals with the effect of temperature and strain rate on the mechanism of deformation of aluminum single crystals similarly oriented for single and duplex slip. The work of several investigators has shown that in aluminum at high temperatures other slip systems in addition to the predicted {I l l) <101> may operate. The most generally reported additional systems

Jan 1, 1959

By James Elton

THIS paper covers, besides laboratory work, a study of actual operation at the Washoe Smelter over a considerable period of time, together with the results of a visit to the Midvale plant of the United States Smelting- & Refining Co., near Salt Lake. For the latter privilege, as well as permission to publish the resulting data herein given, I am indebted to George W. Heintz, General Manager of the Midvale plant, and here take pleasure in. expressing my appreciation for the many courtesies extended to me by Mr. Heintz and members of the technical staff at the smelter. Almost all of the world&apos;s supply of arsenic is recovered as a by-product in the smelting of other metals. It is seen on the market in various forms, the most common being arsenic trioxide, the ? white arsenic " of commerce, which is sold as a heavy white powder, or in white, glassy, translucent masses. The trioxide is used in the manufacture of pigment, glass, and insecticides. About 50 per cent. of the domestic consumption is supplied by imports.

Jan 8, 1913

By S. W. Nabbs, W. D. Bachman, A. W. Last

A study has been made of wet, autogenous grinding of disseminated copper ores, including testing of a large number of samples from. Kennecott Copper Corp.&apos;s Chino mine. The grindability of the various samples was found to vary over an extremely wide range, even among samples taken from diflerent locations within the same ore body. These variations in grindability can be qualitatively correlated with the composition of the rock and the fracturing and alteration that had occurred. Because of the large-scale nonhomogeneity of disseminated copper ore bodies, extensive and careful testing of autogenous grinding is needed. An accurate correlation of the grinding data from various samples with the geology of the ore body and with mining plans will indicate if variations in grinding mill throughput can be avoided in practice by mixing or blending of mill feed and if, therefore, autogenous grinding can be applied successfully. In the past 15 years, comminution by primary autogenous grinding has been investigated and applied economically in the minerals industry, particularly in iron-ore processing. Successful application of primary grinding is described by A. A. Dor,l.&apos; P. B. Dettmer,334 R. R. Turner, and W. F. McDermott." other authors describing the advantages of primary grinding include H. Hardinge,&apos; R. T. Hukki,&apos; D. S. Coyle" and F. C. Bond,"," to mention only a few. For the past several years, Kennecott Copper Corp.&apos;s Metal Mining Div. Research Center has been investigating primary grinding of disseminated copper ores. Both fully autogenous and semi-autogenous grinding has been explored. Ores from three of Kennecott&apos;s western operating properties and from several development properties have been tested. Host rocks include diabase, schist, silicated and argillaceous limestones, shale, granite porphyry, quartzite, and granodiorite. The object of this paper is to supplement the general knowledge in the field of primary grinding by presenting information gained from the studies with the various disseminated copper ores. Data are presented which show that carefully considered test programs are required to determine the practicality of applying autogenous grinding to a specific mining-beneficiation operation. Particularly this is so if more than one rock type occurs within an ore body or if there are wide variations in the degree of rock alteration within a deposit. Extensive sampling and subsequent testing of the ores within a mine are required if serious pitfalls are to be avoided and good engineering data acquired. We hope that this presentation will stimulate studies to increase the understanding of the fracturing process applicable to large pieces of rock, a factor which is important in autogenous grinding. Test Facilities and Procedures Both pilot-scale and full-scale test facilities were used to investigate primary grinding characteristics of the disseminated copper ores. A 6-ft Hardinge Cascade mill, a 24-ft Hardinge Cascade mill, and a 5-ft Aerofall mill were used in the studies. The Cascade mills were operated wet, while the Aerofall mill was operated both wet and dry. The Cascade mills were operated both for fully autogenous and for semi-autogenous grinding; the Aerofall mill was operated only semi-autogenously. Fully autogenous grinding, as the term is used in this presentation, is defined as the direct grinding of coarsely crushed rock by the action of the rock mass. Semi-autogenous grinding is defined as the grinding of coarsely crushed rock with the rock mass supplemented by a steel ball charge. Most of the test work was done using the 6-ft Cascade mill, operated under fully autogenous grinding conditions. Only limited testing was conducted with the 5-ft Aerofall mill and only one ore was tested using the 24-ft Cascade mill. This presentation is concerned, therefore, primarily with fully autogenous, pilot-scale grinding in the Cascade mill. Fig. 1 presents a diagram of the test facilities used with the 6-ft Cascade mill. Principal test equipment consists of a 6-ft Cascade mill, an 18-in. spiral classifier, an elevator, a 2 x 9-ft belt feeder, a conventional integrating kilowatt-hour meter, and a recording wattmeter. In testing, feed charges, adjusted as to weight, were deposited as evenly as possible on the belt feeder every 15 min. The weight of each charge was adjusted to maintain a mill charge of 27 to 30% of mill volume. The classifier was adjusted to obtain the desired size-consist of the final product, generally at 20% + 100 mesh. After equilibrium was established in the circuit, the feed, mill discharge, classifier sand, and classifier overflow were sampled and their size distributions determined. During the sampling periods, the power drawn by the mill was measured to determine the energy consumed in the reduction of the size consist of the ore solids. Fully Autogenous Pilot Grinding Tests on Various Kennecott Ores Typical test results obtained in the 6-ft Cascade mill with samples from Kennecott&apos;s Ray Mines Div., Chino Mines Div., Utah Copper Div., and a development property designated as Mine A are presented in Table 1. As shown, the ores that were ground most easily in the pilot-scale mill were composite mine samples obtained

Jan 1, 1971

By Theodore Simons

Permission to present this paper at the February, 1915, meeting of the Montana Section of the American Institute of Mining Engineers was liberally granted by W. A. Clark, Jr., President-and General Manager of the Timber Butte Milling Co., and by the representative of the Minerals Separation Co. For the many courtesies shown the writer on his visits to the mill and for information supplied, he is indebted to all the officers of these companies, especially to W. N. Rossberg, W. D. Mangam, Hamilton Cooke, Jr., T. M. Owen, T. C. Wilson, R. McGillivary, L. L. Quigley, C. Bartzen and others. The writer takes this opportunity to herewith express to them his appreciation and sincere thanks. Location of Mine and Mill The concentrator of the Timber Butte Milling Co. was built to treat the ore mined at the Elm Orlu mine of the Elm Orlu Mining Co., which carries zinc and lead in sphalerite and galena; copper in bornite, chal-cocite, tennantite, and tetrahedrite; and gold and silver either free or chemically combined with the sulphides of the base metals. The gangue is chiefly quartz, barite, fluorite, rhodonite, and rhodocrosite. The iron in the ore occurs as irqn pyrites. The Elm Orlu mine is situated in Butte, Silver Bow County, Mont., near the northern border of what is locally known as the Butte sulphide-copper belt, about one mile north of the Anaconda mine, and adjoining the Black Rock zinc mine of the Butte & Superior Co. on the southwest. The mill is on the northern slope of Timber Butte, a prominent topographical landmark in the Butte district. This site permits to a large extent the gravity system of ore flow; it presents a convenient and extensive area for a tailings pond; and it is comparatively near to the source of water supply and to existing railroads.

Jan 1, 1916

By Ernest R. Lilley

While American scientific literature contains much information upon geologic conditions controlling the production of oil in Rumania, copper in Chile, and other fuel and metallic resources in many foreign countries, it is singularly lacking in data about the nonmetallics outside of the United States. Thus, though the United States is the outstanding market for European high-quality refined kaolin, and for the chinaware, porcelain, and other products of the European ceramics industries, American literature contains only the briefest references to the deposits from which the raw kaolin utilized is obtained. To the writer, to whom has come in the past year the opportunity of visiting a number of these deposits personally, they have proved of extreme interest both commercially and geologically. It is the latter phase that is discussed in this paper. The older and now largely crystalline rock areas of France, Germany, and other parts of western Europe contain numerous pegmatite dikes of which the upper portions have been subjected to surface weathering and kaolinization in much the same way as those of the eastern portion of the United States. Like the latter, the European pegmatite kaolins have long been known for their freedom from iron and other impurities offensive to the china and porcelain manufacturer. Unfortunately, they are also, like the American deposits, individually of small size and noted for their high costs of production. Deposits of sedimentary clay similar in many respects to the high-quality sedimentary kaolins of Georgia and South Carolina are known and worked, notably in southern Germany and in the Newton Abbott district of Devon and Dorset in England. In general, their relationship to the parent rock from which they were derived is more evident than in the United States and the individual deposits are of smaller areal extent and less regular in outline. While these deposits are of considerable economic importance they did not, because of their similarity to deposits in America, attract and hold the interest of the writer to the extent that several other types of deposits did. It is to the latter, which are so different from the kaolin

Jan 1, 1932

One of the results of the work of the Committee on Precious and Base Metals is that the present Bulletin is as large as some of. the annual volumes of Transactions of the Institute, and we extend our. compliments and thanks to the Committee and express to the members thereof and to. the authors, who have so bounteously given of their time and information, the. sincere gratitude of the Institute. In order to get all these papers printed and distributed to the membership in advance of the meeting, it was necessary to divide the work between two printers. This accounts for the discrepancy in the pagination of the Bulletin; and we also ask the indulgence of our readers in case errors have crept into this preliminary edition during the period of unusual pressure. Program of the Butte Meeting.-The program of the Butte meeting will include six technical sessions for the presentation and discussion of papers and five half-clay visits to mines and metallurgical works. The following program is practically in final form, with slight additions which may be necessary later. Every effort will be made to have papers presented and discussed on scheduled time, so that members who are unable to attend the entire meeting may so plan their trip as to hear and discuss papers in which they are especially interested.

Jan 8, 1913

By William Grady

FACTORS entering into the market value of coal are its grade, and the cost of labor, material, and capital. Reduction in these costs cannot be expected in the future, and it therefore follows that greater economy in their use must be accomplished if it is desired to hold the present markets; more tons of product per unit must be obtained in a given time from both men and material, and means devised for increasing the percentage of lump and domestic sizes. This paper is presented for the purpose of inviting discussion and stimulating thought in regard to the influence of methods of procedure and plans of mining, upon the quality of coal, the economical use of labor, material, and capital, and the cost of production. Even the better methods of the. present day leave much to be desired, and a review of the reasons and necessities for their use may be of value in pointing the way to more economical mining. The writer does not attempt to discuss untried methods of mining, but rather to state clearly and concisely a summary of the results obtained under the several methods of procedure that have been adopted. In some instances a high degree of concentration has been effected, and comparisons of the results obtained with the results of lesser degrees of concentration form an interesting study. It is believed that much may be accomplished in improving the quality, and in the more economical use of labor, material, and capital, by concentration, and it is to concentration in particular that your study is invited. The writer, who .has occasion to visit many mines, most of which ire under different management, has been inclined to the opinion that improvement has been retarded in many ways and that mining has not as yet been entirely freed from the early-day practices which were forced upon it.

Jan 5, 1915

By George W. Maynard

For an account of the discovery and the determination of chromite on Port au Port Bay I am indebted to Mr. Obalski, Government mining engineer for the Province of Quebec. He writes: " In June, 1894, with the authorization of our Government, I went to Newfoundland to examine some asbestos property. Passing through Halifax, I had interviews with some gentlemen who told me that besides the asbestos there was in the same district a big deposit of iron-ore. They handed me some specimens, and, after ascertaining that they were not magnetic, and learning that they were found in serpentine, I said they were chromic iron. I visited the place on June 27, 1894, and confirmed my opinion, pointing out at the same time the importance of the deposit, as appears in my report of July 9, 1894. I do not claim any credit for the discovery of chrome-ore in Newfoundland; but, as a matter of fact. when I came in contact with the Halifax gentlemen they did not appear to know the nature or the value of the mineral until I mentioned to them that it was chromite. "&apos; Mr. Obalski&apos;s report was mainly devoted to the asbestos-deposits. That portion relating to the chromite was as follows: " On the right side of the creek there is a show of chromic iron of good quality, which appears scattered through the serpentine in several places on the face of the cliff for 40 to 50 feet. A few boulders are found farther up at a distance of 100 feet, and also in the ckeek itself. From this point the deposit exists on a relatively large area, the widest exposures being from 6 to 7 feet. Chromic iron deposits in serpentine rock have no regularity, and are merely pockets. In the case of the property in question this rule is not changed, but the pockets look to be of large extent, and could be easily worked." My own preliminary investigation of the property was made

Jan 1, 1898

By Paul Cook

THE ore deposit of the Buckhorn Mines Co., Buckhorn, Nev., is peculiar in being a shallow kaolinized mass of material with basalt walls, and having apparently no direct connection with any of the usual gold-bearing rocks. The average ore contains 16 per cent. waiter of hydration, and the cyaniding of this hydrous clayey material offered unusual difficulties as compared with the typical gold quartz ores of Nevada. The orebody was thoroughly developed; then the mill was built according to the latest cyanide .practice, with such changes as were thought to be demanded by the peculiar nature of this ore. Upon starting the mill, the ore proved more difficult to handle than had been anticipated. It is hoped that an account of how these difficulties were met may prove of interest to anyone having a clayey ore to handle and to the profession in general.

Jan 9, 1916

By V. Vahatalo, E. Hakapaa, H. Tanner

Recently modernized, the surface plant of the Outokumpu mine in Finland incorporates a number of ideas meriting close scrutiny from this side of the Atlantic. The mining methods make extensive use of concrete in some unusual ways. Design of the headframe and surface plant represents the latest thinking of European engineers and includes an integral Koepe hoist. The deposit is in eastern Finland, province of North Karelia, 30 miles west northwest of Joensuu and at 60&apos;44&apos; N, latitude. Pyrrhotite, pyrite, chalcopyrite, and sphalerite mineralization occurs in a shear zone in quartzite near a body of serpentinite. Two lenses have a total length over 12.000 ft, with remaining reserves of the 3 to 4 pct Cu ore estimated at about 15 million metric tons.

Jul 1, 1955