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By Walter Harvey Weed

The enrichment of mineral-veins as a result of the migration of material from an upper oxidized or disintegrated part of a vein to a lower level, where it is redeposited, is now, I believe, quite generally accepted as one explanation of the occurrence of bonanzas in gold- and silver-veins, as well as that of bodies of high-grade ores in cupriferous deposits.* Vogt has called attention† to the fact that there are numerous examples of such rich shoots which are " of exclusively primary character, and dependent upon the laws which governed the original ore-deposition." To this I would add that there are also other examples which are neither of primary origin nor due to descending waters, but. result from a reopening of the veins and their penetration by ascending heated waters whose metallic contents are deposited by reaction with the primary pyrite (and possibly other minerals), forming "secondary" enrichments. My studies of the copper-veins of Butte, Montana, show: That the veins there are of several ages and systems; that the older primary quartz-pyrite veins were reopened by later movements, correlated with a period of volcanic activity; and that they were penetrated by hot alkaline waters carrying copper and arsenic in solution, which was deposited presumably by reaction with the pyrite of the original vein. The enormous development of the Butte deposits, attendant upon the extraction of nearly 10,000 tons of ore a day, has revealed many facts concerning the nature and distribution of the ores. Enargite, the copper sulpharsenate, formerly a relatively rare mineral, is now found to be the chief ore of some veins,

Jan 1, 1903

By Walter P. Jenney

In the limestone area of Tintic and other mining districts of the Great Basin region of Utah, it has been observed that surface-outcrops of ore occur but seldom, and are mainly confilled to points of relatively low elevation, where the veins cross some basin or ravine. Nowhere does a considerable body of ore outcrop on the tops or high up on the slopes of the hills. Mining operations, on the other hand, have shown that large and continuous ore-deposits frequently occur in depth in the limestone, beneath large masses of barren rock. Such orebodies, when followed upward in the lodes, are found to terminate at well-defined levels, without reaching the surface. Yet the minerals-bearing fissures themselves extend above the top of the ore, being often traceable, though barren of all valuable minerals, for hundreds of feet above the stopes in the mines, and even observable in outcrops at the surface. This abrupt cessation of the ore at a uniform horizon does not appear to be connected with any change in the countryrock adjacent to the lodes. The strata above and below this horizon seem to be in every way equally favorable to ore-deposition. Explorations above it have developed an open-fissured country, barren not only of ore, but also of indications that minerals bearing gold, silver, lead or copper were ever deposited in the strata at that elevation. The height reached by the ore, while usually constant throughout the length of a given lode, may vary in particular sections, from the operation of local causes. Each lode in a district has its own distinct horizon, above which the oredeposits do not extend. Where the ore-bodies are continuous

Jan 1, 1903

On the Hauraki goldfields, within the limits of Cape Colville Peninsula, the Paheozoic rocks are confined to the district north of a line drawn from Mercury Bay on the east coast to Rocky Point on the shore of the Frith of Thames. South of Kennedy's Bay they are developed on the east coast only at Kuaotunu, at which place gold mining is carried on in sandstones and slates of this age. Between Tapu Creek and Coromandel there is, along and adjacent to the shore of the gulf, a very considerable development of PaJreozoic and in part of Trias rocks, and between the Tiki Stream and the northern end of Tokatea Hill, along the western slope of the main range, lies the special area of the Palreozoic or carboniferous rocks that have more particularly to be dealt with in this paper. The same formation has a large devolpment between Cabbage Bay and the northern slopes of Moehau, and appears to the water marge on both sides of this part of the peninsula.In this part they are of special interest as having, on the west spur of Moehau, a considerable variety of dyke rocks intruded into the sedimentaries, the interest in which is increased by the fact that these dykes theIllselves are of Palreozoic age and correspond to the dykes that are so' abundant in the Tokatea-Tiki area. It is this Tokatea-Tiki area as a goldfield, and its rocks as distinguished from later volcanic' products' on other parts 'of the peninsula...

Jan 1, 1903

By William M. Courtis

While assaying some copper carbonate ore from the Frazer claims, Similakameen, B. C., I noticed that on parting the gold button a deep orange solution was formed. The button gave off pink bands in the nitric acid, which became deep orange at a short distance from it; and as it traveled over the surface of the porcelain dish, it left a deep orange track behind. As the button brightened in the cupel, it appeared to have a bronze color; but I have since found that when amarillium is in large excess of the gold, the button is a very dark gray. The button parted easily. To the orange solution I added a salt (NaCl) solution, shook in a silver testbottle, and filtered. With H2S I obtained a precipitate, which I supposed due to platinum. However, on further tests, it did

Jan 1, 1903

As this district is so far distant from the other mining centres and its mode of approach so circuitous, I am afraid that many residents of other portions of the Commonwealth never think of paying this" Australia's Silver City" a visit, to learn personally the many and various lessons everywhere available, and to become familiar with the really wonderful and interesting features and deposits (which pature has so lavishly bestowed in the mineralogical world) yet seemed to almost ignore or overlook when disposing of topogr,aphical beauties of landscape and vegetation) unless professional or business duties require their presence here. So it is to those whose life is necessarily spent in other parts of the States where they answer their call of duty, and yet feel an interest, either for business or other reasons, that my paper is specially addressed and prepared, and for that reason I witl endeavour to make my remarks more of an explanatory than a dictatorial nature. I feel sure that there. are many members of our Institute who are much more familiar, and have had many more years' experience in the various methods of timbering, filling, and ore extraction, etc., than myself, but I hope that over I6 years' experience in connection with mines and engineering works, the last six of which have been spent in Broken Hill, where, I have been very closely connected.

Jan 1, 1903

By T. A. Rickard

In a former paper* the writer has described the essential features of the general geology of the Cripple Creek region. In the present account it is intended to examine into the occurrence of the ores, the value of which has made this district the most important among existing American gold-fields. The production of Cripple Creek from its discovery, in 1891, to the close of 1901, has reached a valuation of fully $125,000,000. During the past year (1901) the output amounted to $17,285,470. In 1900 it was $18,174,681. The first discoveries, which led to the development of the district, were made in the spring of 1891, but it was not until 1893 that vigorous work was commenced. A great impetus was then given to the exploration for gold on account, of the sudden drop in the market-price of silver, caused by the closing of the Indian mints in the summer of that year. This induced an energetic population from the older silvermining camps of Colorado to go to the new gold-field, which was then beginning to attract attention. Prospecting, at first, was hindered by the comparative absence of outcrops, due to the fact that the surface of the hills is covered with a considerable thickness of shattered rock, resulting from the action of frost at a high altitude; but so much indiscriminate digging was done that a number of rich veins were uncovered, and this stimulated the search for others. The advanced condition of the mining industry of Colorado offered unusual facilities for exploration and reduction; progress was therefore rapid, with the result that the district soon achieved great prominence.

Jan 1, 1903

Jan 1, 1903

Willet G. Miller, Toronto, Canada (communication to the Secretary): In his interesting paper Mr. Lindgren says: " As to ultimate results, it would seem as if we should be justified in concluding, with Prof. Suess, that the gold-supply of the world will gradually decrease if no further important improvements are made in the processes for the extraction of this metal; but regarding events so far distant no predictions may safely be made." It seems to the writer that no very important improvements require to be made in order at least to keep up the present production for many years to come. In many parts of the world there are large deposits of auriferous material which can be worked if present conditions are slightly changed. In the territory occupied by the Archean protaxis of the Province of

Jan 1, 1903

Since I have had the pleasure of watching the development of this process very closely, I feel that I ought to say a few words on the subject, although I cannot add much to what Mr. Roe has already said. I wish, however, to bear witness to the hard work, persistence and skill which have been exercised during the past two years, and which have so well deserved the success attained. Those of us who remember the history of the past efforts in this line, such as the rotary puddlers, in which also some of us had a part, can easily appreciate the problems involved, and may well be skeptical as to the outcome. Such, at least, was my frame of mind when the process first came under my notice. Now, after having seen every heat, but three, of the many made, it really seems to me that a process and plant for the mechanical puddling of iron has at last been developed which is practical, economical and successful. Of course I do not mean by this that either the process or the machines are developed to their highest point, technically or economically, but that, in my opinion, these goals are in plain view, and that the difficulties which remain are such as will be overcome by developing the skill of the operator through practice ;

Jan 1, 1903

George Smith, Sydney, N. S. Wales (communication to the Secretary): The very interesting paper by Mr. Emmons on " The Secondary Enrichment of Ore-Deposits " has just come under my notice; and its reference to my own paper* on " The OreDeposits of the Australian Broken Hill Consols Mine "† is therefore only noted some two and a half years after its publi-

Jan 1, 1903

In traversing lately the Sierra Madre, west of Sail Pedro and Guanacevi, I estimated the topographic summit at several points, by aneroid barometer, at about 8,500 ft. Mr. Weed's measurements, 40 miles further north, are from 9,000 to 9,500 ft., and indicate the correctness of the impression I obtained at the time, namely, that the greatest movement in the elevation of the Sierra was between Guanacevi and Guadaloupe y Calvo. This is suggested also by the course of the headwaters of the Rio Conchas and of the Nazas, and by the relative corrasion of the branches of the two streams. Mr. Weed's statements as to the unevenness and great relief of the andesite floor underlying the later dacites and rhyolites are very interesting, and lead me to add that the floor of the andesite breccias and flows is uncovered for several square miles east of Guanacevi. This floor is of reddish, bluish and gray shales, lying horizontal or dipping slightly east. Their age is unknown; but from the interbedded occurrence of copper sulphides, I took it to be Triassic,

Jan 1, 1903

Professor Jenney has performed a notable service in presenting this summary of the steadily increasing body of observation on the presence of carbon in rocks of all kinds and its probable influence upon ore-deposition, and in formulating a mode of comparing directly the relative resistance of minerals to oxidation, as well as their reducing-power, and the protective action which minerals having higher reducing-powers exert in preventing the oxidation of associated minerals which possess relatively lower affinities for oxygen. I have had an opportunity of observing a vein which falls within the scope of his interesting discussion. The vein at Ku Shau Tzu, Mongolia, lies directly across a contact of limestone and overlying bituminous shales. Probably it occupies a compression-fissure. The shale has been reduced to such a condition of' non-coherence that much of it can be crushed in the hand, producing a handful of angular fragments resembling beech-nuts in shape and size. In the limestone the metals are principally in argentiferous galena with some pyrite and blende; but the latter two are very subordinate in quantity to the galena. In short, it is an every-day lead-vein in limestone, with siliceous limestone gangue. It is one of those veins in which the ore is not continuous, but consists of a band in the country-rock in which seams of lead sulphide begin at one wall and cross in a bent form, increasing in thickness, to the other wall, where they thin out and end. This may indicate torsional stress, but the shape of the lenses points to some other action. They often ran nearly parallel to the hanging-wall for a considerable distance and crossed the vein on a moderate angle, but turned sharply along the vein on approaching the foot-wall. The intermediate rock contains nodules, bunches and specks of ore, and the lenses vary exceedingly in size, shape and position in the vein.

Jan 1, 1903

David T. Day, Washington, D. C.: The paper of Mr. Adams is chiefly valuable because it emphasizes the ease with which petroleum can migrate in the earth's crust. Concerning this migration, I have little faith in the rôle of water as a carrier of gaseous or liquid hydrocarbon, suspended or mixed in the water in any way. My lack of faith is due to observation of

Jan 1, 1903

In Mr. Weed's interesting paper, frequent reference is made to the Cananea copper-deposits, which are said to have been so vigorously exploited that they produced 14,000,000 Ib. of copper in 1901. The ore-bodies which yielded this large quantity of metal are described as a product of contact-metamorphism, and in Mr. Weed's genetic classification of such deposits, they receive a place under the sub-heading, "Deposits impregnating and replacing beds of contact-zone."* They are considered by Mr. Weed to represent a special type under this head, and are further classified as: " l. Chalcopyrite deposits: (a) Pyrrhotite ores; (6) Magnetite ores, Cananea type." In condensing much information into a comparatively small space, the presentation of a subject may be so abbreviated as to detract from its clearness. The situation at La Cananea, considering its importance from an economic as well as scientific standpoint, may he worthy of more detailed description. As Mr. Weed rightly remarks, " structural differences are so important, and have SO marked a bearing, not alone on the theory of their genesis, hut also on the working of the deposits and a determination of their value as mines, that they merit a full discussion."† It is my present purpose: (1) to show that it is doubtful whether the copper of La Cananea is mined, except to a limited

Jan 1, 1903

The subject of my paper is one which, I am certain, has exercised the mind of every man on whom depends the safe and economical conduct of mining operations; particularly in this district where the enormous size of the ore body has necessitated the mine workings assuming a scale that was hitherto unknown in the history of Australian mining. I, therefore, approach the subject with the feeling that I am displaying considerable t.emerity, knowing as I do that the subject has engaged the earnest attention and thought of everybody immediately concerned in the extraction of the ore of this district, and particularly of the Broken Hill lode.I think I shall not be contradicted in asserting that a very large proportion of eur accidents are distinctly traiceable to inexperience on the part of the miner, and records at the mines and verdicts of coroners' juries in many instances uphold this assertion by showing that the accident under notice was the direct result of lack of knowledge of the conditions of the work, or, at any rate, of an error of judgment hardly conceivable in the experienced miner. That this assertion is correct may also be proved by visiting any of the mines of the district.To the experienced eye it will be evident at once that a very large number are not in way skilful in the use of their tools and, therefore, lack the experience which of necessity must be coincident with the acquirement of skill. Now in making this' assertion, I do not intend to be too sweeping...

Jan 1, 1903

By Charles V. Jenkins

The structure of steel, when rendered coarse by over-heating, is made fine by re-heating to a certain temperature, the determination of which has received much attention from eminent metallurgical authorities. Among these, I may particularly mention Prof. D. Tschernoff' [Chernoff], who, about thirty years ago, studied this question in connection with his investigations on the structure of steel in genera1. † Some years later, Mr. J. A. Brinell took up the inquiry, and arrived at many important conclusions, stated in his well-known rules on the treatment of steel. ‡ These two gentlemen, however, based their reasoning chiefly upon the aspect of fractures—a method which, though it affords valuable information, does not readily reveal the different steps by which a change in structure takes place. For further light on the subject, we owe much to more recent microscopic investigations, which have made us better acquainted with the internal structure of metals. Such an investigation, closely connected with the present subject, and made by Mr. John E. Stead a few years ago, was first published in 1898.6

Jan 1, 1903

George Otis Smith, Washington, D. C. (communication to the Secretary) : The somewhat exceptional features discussed by Dr. Jenncy in his paper on " The Mineral Crest" mere recognized and described by Mr. Tower in our report on the Tintic district. The general absence of surface-outcrops of important ore-bodies, and their occurrence, when present, at relatively low points, are noticeable characteristics of this district, and the statements made by Dr. Jenncy agree in general with our observations. The approximately horizontal upper limit of the Silver Gem ore-body in the Bullion-Beck mine is figured in this report, and mention made also of the horizontal pipes of ore found in several mines." In only one case," however, was any hypothesis

Jan 1, 1903

By Joseph A. Holmes

The public is already familiar with the general fact that the scope and the financial resources of the approaching St. Louis World's Fair are much larger than those of any of the preceding great expositions; and both the visitor and the exhibitor, when he comes to St. Louis in 1904, will find it to be a real World's Pair, with exhibits and visitors from every known country. Passing over the subject, as to the general Exposition, with this brief statement, I ask Sour attention to the consideration of a few important facts connected with the proposed mining exhibits at this Exposition. First of all, I may say that. reading- and writing-rooms and library facilities will be furnished in the Mines Building for miners and mining engineers, and it is expected that when they visit the Exposition they will make these rooms their headquarters, and give the Chief of the Department and his assistants an opportunity to extend to them such courtesies as may be possible. One of the exhibits in the Mines Department will consist of models and maps arranged to show the nature and extent of the mining operations in the United States at the time of the purchase of the Louisiana Territory in 1803, the event which

Jan 1, 1903

Alexander N. Winchell, Butte, Mont. (communication to the Secretary): Mr. Spurr calls attention to the fact that an ore-deposit may be due to a succession of concentrations at different geological epochs. He cites an example of such a condition on Napoleon creek, a branch of Forty-Mile creek, Alaska. It will perhaps be of interest to call attention to another example of the same general character, not so remotely situated. The example referred to is located on Pole creek, a tributary of Cherry creek, in the extreme northeastern part of Madison county, Montana. An excellent geological map of this region is to be found in the Three Forks folio (No. 24) of the United States Geological Survey. According to this map, Pole creek, in its upper course, occupies the contact between the " Flathead " formation, which Peale correlates with the Middle and Lower Cambrian, and an area of gneisses and schists supposed

Jan 1, 1903

MR. Woo's succinct description of the mining and smelting of silver-lead in Mongolia, with the roasting-and-reduction process and cupellation, has much interest as a picture of methods that not only may have been in use, as he suggests, a thousand years ago, long before the existence of mining schools or chemical laboratories, but probably vary little, if at all, from the practice of prehistoric times, when King Priam's handsome silver vases, cups and bowls were formed. For it is highly improbable that such large objects were made from comparatively rare native silver, and the metal must have been smelted from ore, and most likely in great part from galena,, with cupellation of the lead. Dr. W. A. P. Martin, in his excellent book on the Lore of Cathay, points out that Chinese alchemy is over 2000 years old, antedating the European by at least six centuries; and he infers that the Chinese skill in metallurgy and many branches of practical chemistry owes its origin to " those early devotees of the experimental philosophy who passed their lives among the fumes of the alembic." Those alchemists, however, may have more likely derived some of their leading ideas from the mys terious, and at that time wholly unexplainable results observed in already very ancient metallurgical processes; in which, for example, certain stones were transmuted, as it were, into metals widely divergent in character from their ores, and even silver and gold were obtained from the most unlikely-looking mate rials. It is therefore, in any case, not improbable that the Chinese may have preceded western nations in the discovery of metallurgical methods. At all events, it is now evident that the Japanese acquired these arts from China, the former source of all their higher civilization. My own observation of old-fashioned silver-smelt ing at Hosokura, on the main island of Japan, and about 220

Jan 1, 1903