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F. Lynwood Garrison, Philadelphia, Pa. (communication to the Secretary): I have been specially interested in Mr. Drake's valuable contribution to our knowledge of the Chinese coalareas, as I had occasion, about a year ago, to make a reconnoissance over some of the coal-fields in the Yangtse river valley. I noticed, as he appears to have done, certain peculiarities which may eventually prove to be characteristic of the Chinese coal-measures, at least in central and northern China. The most striking feature, perhaps, is the invariable proximity of the great granite masses to those coal-deposits which have an anthracite character. In common with all other anthracite areas elsewhere, the Chinese show evidences of profound stratigraphical disturbances. The sedimentary rocks are folded, faulted and dislocated in a manner similar to those of the Pennsylvania anthracite-regions. It would seem that the intrusive granite had much to do with converting the original bituminous into present anthracite. The action of the granite was probably direct as a conveyor of heat, and indirect as dynamic force in dislocating, overturning, and compressing the coal-measures. My stay in China was unfortunately cut short, so that I was unable to collect fossils, or to give this highly interesting and important subject more than passing attention. Cholnoky* and Richthofen are practically agreed that these granite eruptions took place during the Tertiary period—probably the Eocene. This profound tectonic movement has had a most important effect upon the geological conditions in central and northern China, and will be, I am sure, a potent factor in the economic development. Evidences of disturbances and metamorphism are very abundant in the anthracite-areas of the Yangtse valley. I noticed the coal in them, as did Mr. Drake in northern China, to be often flaky and " slickensided."

Jan 1, 1902

Henry D. Hibbard, New York City (communication to the Secretary): The title of Mr. Sargent's paper is somewhat misleading, since the paper itself relates chiefly to various kinds of annealing and their effects, and in very small part only to heat-treatment proper. This term has a well-defined meaning in steel metallurgf, and always includes a rate of cooling faster than the material treated would have in the open air. In bringing about this accelerated rate of cooling, some medium other than air at rest is brought into contact with the heated steel. Usually a liquid (almost always either oil or water) is employed ; but for certain steels a blast of air, and for others an easily fusible or soft metal, such as led (either solid or melted), may be used. Heat-treatment usually includes also subsequent moderate heating, followed, it may be, with another accelerated cooling.

Jan 1, 1902

S. F. Emmons, Washington, D. C.: Mr. Malcolmson's paper on the intensely interesting deposits of the Sierra Mojada creates a strong desire to visit the region so well described. Although it is difficult to intelligently discuss a locality that one has never seen, I cannot refrain from offering some remarks in the nature of a tentative suggestion: 1. Age of Beds.—Mr. Malcolmson speaks of the enormous thickness of limestone forming the Sierra Mojada as belonging to the Carboniferous series. If this is not a typographical error, it seems that he should present some evidence for such age, for Chism,* in his previous article on the district, says the only fossils found there were said to be Cretaceous; and it is well known by the investigations of R. T. Hill and others that the great thickness of limestone in this part of Mexico is of Cretaceous age. 2. Structure of Mountains.—Mr. Malcolmson presents good reasons for thinking that the structure of the two related mountain masses (Sierra Mojada and Sierra Planchada) is not the simple anticlinal fold given by Mr. Chism's section, it being evident that there has been faulting as well as flexure. I venture to add that the facts presented by Mr. Malcolmson seem to suggest the possibility that, instead of being simply an eroded anticline, the valley between the two ranges may have been formed, in part at least, by the irregular faulting down of the intermediate block, on the surface of which the volcanic breccia had originally accumulated at a higher level. The sections of the Exploradora and the San Josh mines, in the smooth surface of the contact, with clay selvages and the occasional slickensides, certainly suggest a structural fault between the limestone and breccia. The arrangement of some of the

Jan 1, 1902

Edward Halse, Puerto Berrio, Colombia, S. A. (communication to the Secretary): I have read with much pleasure the interesting and valuable paper by Mr. Kunz, and hope that the following brief notes, gathered a few years ago, while a resident in Mexico City, may help to elucidate the subjcct: Turquoise.—This was known to the Aztecs as Xihuitl. Santiago Ramirez states that they found it in the Cerro Xicohtzonc, close to Atzcapatzalco, a suburb of the City of Mexico (compare page 59). Opal.—This was known to the ancient Mexicans, for they named it mezcuitlatt (compare page 63). Jade.—Under this was iucluded a third mineral, prehnite, not mentioned by Mr. Kunz. According to James D. Dana, part of the "jade " of China is prehnite; and Humboldt informs us, in his work on New Spain, that the same species of jade is known in some parts of Mexico as mahagua (majagua ?). The same writer says, in his Views of the Cordilleras, that the Aztec name Tecpatl included flint, hornstone, and green jade; and finally, in his Travels in South America," he discusses the nature of the ancient amazon-stones, and declares them to have been made out of a jade resembling " compact feldspar," one of the constituents of the gabbro verde di Corsica. IIence those stones were probably composed of nephrite. According to Humboldt, the form given to them most frequently is that of the Babylomian cylinder, longitudinally perforated, and loaded with inscriptions and figures. They were also cut by the natives into very thin plates, perforated at the center, suspended by a thread, and worn as amulets. According to the historian Clavijero, the specific name given by the Aztecs to the nephritic stone (jadeite) was Quitzalitztli,

Jan 1, 1902

By John H. Harden

In the valuable paper of Mr. Dunbar D. Scott and its varied discussion, on the evolution of mine-surveying instruments, the tripod-head has not received the attention it merits. During the last 50 years this very necessary adjunct to the surveyor's instrument has been much improved. The legs are of better construction; and the devices for laterally moving the instrument over the station-point and for quick leveling, without the use of the screws, have given to the instrument fitted with the modern tripod-head the same facilities possessed by the oldfashioned ball-and-socket, with more perfect accuracy, not attainable in the latter, while saving from 30 to 50 per cent. of the time required for setting the instrument over a station. For the purpose of extending the discussion to this import-

Jan 1, 1902

Alexander Forsyth, Southport, Me. (communication to the Secretary): In Mr. Irving's able and interesting paper he describes minutely the appearance of the wolframite and its association with the refractory siliceous gold-ore. He also describes this gold-ore, but fails to mention the important pockets of metallic gold found in the Lead City occurrence of it. I use the term " metallic " in preference to the more usual " free," for it has been found that this gold is not easily amalgamated. Metallic gold is comparatively rare in the refractory siliceous gold-ores of the Black Hills; hence its occurrence in considerable amounts in the Lead City wolframite district deserves notice. I possess a beautiful specimen from the Harrison mine. It is a lump of drusy, granular ore, about 6 in. in diameter. The gold .is " shot" through it in large and small pin-heads; and in two specially oxidized areas, each about 11/2 in. in diameter, it is peppered full. The famous " Grantz strike," made in the Lead City wolframite locality, produced many beautiful gold specimens. This district affords an excellent example of the repeated discovery of new mineral values upon old ground. By reason of its proximity to the Homestake vein, this wolframite deposit was inevitably traversed many times by experienced geologists, mineralogists and mining engineers, who evidently must have thrown aside, with no thought of wolframite, the lumps of " black iron " lying about. I have the admission of an able geologist that, six months before the wolframite was discovered, he visited some of the very mines where it occurred, and passed it by as magnetic iron-ore. At the time of the discovery, the mineral was scattered over the gold-mine dumps in no small quantities, having been culled as worthless out of the gold-ore. It remained for

Jan 1, 1902

Prof. J. C. BRanner, Stanford University, Cal. (communication to the Secretary): On p. 398, Mr. Hedburg mentions Marionite and Brannerite as ores of zinc. Neither of these has been authoritatively recognized as a distinct mineral species. Marionite, originally described by Elderhorst, was subsequently determined to be nothing else than hydrozincite. Analyses of the so-called Brannerite were sent by me to Prof. Penfield, who says it is a mixture of Smithsonite with some other mineral. On p. 398, Mr. Hedburg says the zinc-bearing formation of North Arkansas " is recognized as the Upper Silurian." So far as my observation goes, the ores occur both in Lower Carboniferous and in Ordovician or Lower Silurian rocks, but nowhere in rocks known to be of Upper Silurian age. If Mr. Hedburg has any paleontological evidence of the Upper Silurian age of these rocks, or of any of them, he will confer a favor upon geologists by making it known. On the same page is another statement in which I cannot concur. He says that in this region, " it can easily be seen that the largest fissure-deposits have been eroded and washed away, leaving here and there a few patches adhering to the hillsides." I am compelled to say that in many years' study of the geology of the region in question, I have never been able to recognize such a state of affairs as Mr. Hedburg here describes. The patches which he regards as remnants of fissure-veins, " adhering to the hillsides," I have found to be either the edges of bedded deposits, or portions of the zinc-bearing breccias, formed along old drainage-lines, and laid bare by the ordinary processes of erosion. That fissure-deposits have been partly removed by the same agency, goes without saying; but it is, in ,my judgment, no more true of North Arkansas than of any other mining-region that erosion has selected and washed away " the largest " deposits. My own views of the region in question are given in detail

Jan 1, 1902

Frank H. Probert, A.R.S.M., Morenci, Arizona (communication to the Secretary): The management of mines and the system of bookkeeping employed are subjects of great interest to mine-superintendents, and such papers as that of Mr. Davis callnot fail to attract attention. The Institution of Mining and Metallurgy, London, England, has done much within the last three years to promote discussion on the many systems adopted throughout the mining world; and any papers giving individual experience will benefit that class of men who are charged with the cconomical management of mining properties. It is often said that " a good mine shows a good manager," and more often that mismanagement is the chief cause of poor returns; or, as Mr. A. G. Charleton puts it, in his able paper on " Mining Accounts and Cost-Sheets,"* " accident may, and often

Jan 1, 1902

Mr. Tays (communication to the Secretary): Mr. Wynne's criticism of my paper* brings forward a few points which are really important, and might properly have been considered in the original paper. By calling attention to them he has rendered me a service. It is quite true, as Mr. Wynne says, that, in the tests reported by me, the Bryan mill was always working at a relative disadvantage, and my comparison of the work of this mill with that of the stamp-battery should be interpreted, therefore, so much the more favorably to the mill. Of course, wire screens can be used to advantage on the Bryan mill, if they are not of smaller size than 30-mesh; but

Jan 1, 1902

Jan 1, 1902

By J. Ralph Finlay

In latitude 4" S., about fifty miles from the Pacific, and in the amphitheater on the west flank of the Andes, which is drained by the river Tumbez, is the ancient town and mining district of Zaruma. The town is picturesque in the extreme, perched on a ridge 1800 feet high, between two lovely mountain rivers, looking out upon neighboring hills and valleys clothed in rich green, relieved by many hamlets roofed in red tiles, and, at greater distances on all sides, upon mountain slopes of gloomy forest crowned by the bare summits of the Andes. General Description. The gold-mines, discovered in 1549, mere worked extensively by the Spaniards in the 16th and 17th centuries, until their success was curtailed by the exhaustion of the oxidized surfaceores, and the uncovering of the refractory and hard ores underneath. The industry slowly declined until it was nearly or quite at a standstill in 1878, when an unfortunate English company, organized by Chilian promoters, acquired some of the best properties and began to work them. This company, after an extravagant début, relapsed into a struggle against poverty and mismanagement, and finally collapsed in 1894. In 1896 the English mines and many others, covering most of the district, were acquired by the South American co., formerly the South American Development Co., of New York. (See Figs. 1 and 2.) The vein-formation of Zaruma is extensive and complex, and the ores are somewhat refractory. In the immediate neighborhood of the gold-bearing veins the formation seems to be altogether volcanic, consisting of rather fine-grained holocrystalline diorite; but a few miles away, on either side, some gueisses and crystalline schists are to be found. About four miles south of the mines, and beyond some intervening granites, appear

Jan 1, 1901

Jan 1, 1901

By L. D. Godshall

The extreme difficulty of obtaining a short and, at the same time, exact method for the determination of gold and silver in copper-materials has been well illustrated in "Assays of Copper and Copper-Matte," and its discussion, by Dr. A. R. Ledoux and other leading authorities on this subject.* Two general methods were used by the numerous assayers who took part in the symposium initiated by Dr. Ledoux, and whose results are given in the paper and discussion. One of these is the dry or fire-method, consisting of scorification and cupellation, the former being repeated if the percentage of copper is very high, all slags and cupels being assayed and the results so obtained added to the ordinary assay; and the copper retained by the silver buttons being determined and deducted from the combined weight of the buttons obtained from the assay of the original material, the scorification-slag, and the cupel. The other is the wet or combination-method, which, while not involving so much work, requires a longer time. Briefly, it is as follows : The material to be assayed is dissolved in nitric acid, the solution is diluted, and the fine undissolved gold is collected by means of sulphate of lead, formed by the addition of lend acetate and sulphuric acid to the solution, After standing from 12 to 24 hours, the precipitate is filtered off, and the silver in the filtrate is precipitated as a chloride or bromide, and collected by means of sulphate or bromide of lead. The solution containing this precipitate in suspension is again allowed to stand until the precipitate has settled. It is then filtered; both precipitates, containing the gold and silver, are dried, ignited and scorified, either separately or together, and the result is cupelled in the usual way.

Jan 1, 1901

W. M. Courtis, Detroit, Mich. (communication to the Secretary) : Having made a rapid examination of the deposits described in this paper, I am not inclined to generalize confidently concerning its geological relations. But, since an analysis furnished by me has been included in the paper, it may be of further use to give the results of other samples and analyses. I give, therefore, a table of analyses by different parties, showing the average from surface-specimens:

Jan 1, 1901

The limit of pressure to which an underground dam may with safety be subjected, is a question that-as far as the writer knows has not received the same attention from authorities on engineering construction, or practical mining, that has been accorded to questions on which the design and strength of other structures or machines in connection with a mine are based. That dams may, under certain conditions, be constructed to resist water under great pressure is a known fact. But the difficulty of demonstrating beforehand that any proposed structure of this kind will withstand the pressure and be effective is, owing to the indeterminate nature of some of the risks to be provided against, very great. In the present state of our knowledge it may almost be laid down as a rule, that a dam of this kind should not be undertaken where grave consequences would attend failure until experience of structures where the physical conditions are similar, but where there are no such risks, has given assurance that such work would stand.In Mines and Minerals for May, 1900, there is published a paper by Mr. James McNaughton describing the construction of three underground dams in the iron mining district of Michigan.The first of these was put in to hold back a flow of 750 gallons per minute, which when pent up created a pressure of 276 pounds per square inch, showing that the height of the sustained column was about 635 ·feet. The hole through which the water issued was in the bottom of the cross cut it was enlarged by removing all loose rock for a depth of 18 ft...

Jan 1, 1901

By Bailey Willis, George Otis Smith

I. Summary of General Features. Location.—The Clealum iron-ore deposits occur on Clealum river, a tributary of the Yakima river; in the eastern spurs of the Cascade range, Washington.† Mount Stuart, 9470 feet in altitude, is a dominant peak of the district, which will therefore be referred to as the Mount Stuart district. By way of the valley and cañon of the Clealum, the ores are 18 miles from Roslyn, the colliery-town, which is reached by a short branch from the Northern Pacific Railroad. Where they occur the valley has an elevation of 2900 to 8000 feet above sea; that of the end of the branch railroad at Ronald is 2345 feet. The grade of the valley from near Ronald to the junction of the Clealum and Salmon Lasac rivers, 144 miles, is 20 feet per mile; thence to the iron-ores it is 130 feet per mile, through a cañon 241/2 miles long. Abreast of the deposits the western wall of the valley is formed by precipices of sandstone; the eastern slope is comparatively gentle, being cut in easily eroded

Jan 1, 1901

Jan 1, 1901

By S. F. Emmons

It was said by many who discussed Professor Posepny's admirable paper on the "Genesis of Ore-Deposits," read at the Chicago meeting of the Institute, in 1893, that its most valuable feature was the clear distinction which it drew between the influence upon ore-deposits of the " vadose " circulation of waters descending directly from the surface, and that of the deep underground circulation of waters generally coming from the depths, and assumed by the author to be ascending through more or less open spaces under the influence of heat. A little later the effect of the oxidizing action of the vadose circulation upon ore-deposits was ably and exhaustively treated by Prof. R. A. F. Penrose, in a paper on " The Superficial Alteration of

Jan 1, 1901

Taking the third meridian as the eastern boundary of proved payable auriferous country, there is a stretch of country, nearly 600 miles in width, in which no appreciable amount of gold has yet been discovered. Many prospectors have attempted to .penetrate or traverse it, but comparatively few have thought it worth while proceeding with the examination.The desolate stretch of waterless desert-the very few and insignificant outcrops through the sand and the almost total absence of feed for horses have, combined, presented such a barrier as to preclude prospecting. The few who have traversed the country are eloquent in denunciation, yet their investigations, necessarily hurried, are not quite satisfactory. The absence of water utterly debars a thorough examination being made. Gold may exist in quantity, yet it would have to be extraordinarily plentiful to render its obtaining profitable. Too fantastic is the idea of its ever being a mining district; shifting sand to traverse, utter absence of wood and water render the notion absurd. Likely looking belts occur, but these in all "cases are small and remote from water. Gold has been obtained from likely look ing quartz reefs, but only by fire assay, and then but a few do to the ton. Without wishing to be pessimistic, I would unhesitatingly declare that east of the third meridian, and between the parallels 25 and 30 degrees in West Australia, there is no gold in payable quantities.

Jan 1, 1901

In the course of the last twenty eight years the copper lodes of New Caledonia have been periodically worked or abandoned, until quite recently, probably attracted by the higher price of the metal, British capital has again been induced to embark upon the further development of several copper properties, which at present give reasonable promise of becoming regular producers. Owing to its proximity to Australia (only a three day's journey by mail steamer from Sydney) New Caledonia becomes of additional interest to Australian commerce in general, and it is to be hoped that the French Government may see their way before long to make the best of this natural position, to the mutual benefit of both countries concerned.Op till now all copper ores and concentrates which have been shipped from New Caledonia, were treated in Australian smelting works furthermore, Australian mine managers and miners have from time to time been connected with New Caledonian mining ventures, but, unfortunately, it must be said that nearly everyone of them returned to Australia thoroughly disgusted with his experience over there. Even to the casual observer, it is not so very difficult to find a proper explanation for these shortcomings in the peculiar economic conditions of the 'French colony, as many of the objections which have hitherto existed in connection with mining operations, were the direct consequences of a system of colonisation which could not possibly have been productive of better results.

Jan 1, 1901