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By T. Egleston

I HAVE to announce with great regret that our distinguished honorary member, Louis Gruner, died in Paris in March last. The Institute, in his death, has lost one of the first as well as one of the greatest of its honorary members. I speak with great feeling, as he was both my instructor and my friend ; and I am sure that if he could hear what I am about to say of him, lie would object to it. Mr. Gruner's modesty was such as even to prevent, except in his own Corps, the thorough appreciation of his work in his own country. I think be mas better appreciated by those who are familiar with his labor in almost any other country than his own. A just man, a thorough scholar, a great investigator, he was so unselfish that almost the last act of his life, and the last letter he signed, only a few hours before his death, had for its ohject to render a service to one of his former pupils. I think no one who mas ever associated with him could forget, in the greatness of his learning, the sincere and earnest friend, mho was always ready to render a service, where such service could be rendered even at great inconvenience to limself. His own motto, "Sein, nieht schein;" that is, "Be, not appear to be," was singularly descriptive of his character; and, what is more than all, he was one of the most earnest Christian men with whom it has ever been mv. good fortune to be thrown in contact. There are few such men. He was one of the greatest metallurgists that Europe has ever produced; a man the more remarkable because, though known to most of us as a metallnrgist, some of the best work of his life was in the domain of geology to which he contributed very important researches and memoirs, which will remain permanently among the valuable additions to the geology of his own country. He was, at the same time that he was the greatest metallurgist in Europe, a brilliant chemist, a thorough geologist, a distinguished professor, and an expert, practical miner, whose advice and methods had only only to be known to be followed. Mr. Gruner was born in Smitzerland in 1809, and graduated from the Polytechnic School of Paris in 1530 and entered the School of Mines, from which he graduated with distinction in the Corps of Government Engineers of Mines at an early age, and was immedi-

Jan 1, 1884

By J. M. Ohm, C. M. Bunker

Two special tools for recovering gamma-ray probes and logging cable from drillholes have been designed by Ohm and Bunker and constructed by Ohm. Though intended specifically for U. S. Geological Survey equipment, they may be used with other equipment of the same general type. Fishing Tool for Probes: A fishing tool of the overshot type (Fig. 1) was designed to retrieve logging probes (sondes) that become disconnected from the logging cable and are trapped in the drillhole. When the tool slides over the top of the gamma-ray probe, studs on the bottom engage the shoulder near the top of the probe (Fig. 2), which is then pulled to surface. The barrel can be constructed from brass or steel tubing. Wall thickness is not a critical dimension, but the tool should be heavy enough to sink through mud or water in the drillhole. The internal length of the tool must be enough to prevent interference with the upper end of the probe head as the tool slides over it. The design of the probe head used by the USGS required a minimum free space of 2 1/2 in. inside the fishing tool, which was made 7 1/2 in. long to increase the weight. The lower end, which engages the shoulder of the upper end of the probe, contains three studs placed at 120" around the circumference of the tool and held in the engaging position by the tension of a spring wire. The studs can be made of any metal, such as steel, having high tensile strength. As the tool slides over the probe the studs are pushed outward from the center against the spring tension, allowing the tool to slide into position below the shoulder of the probe head. The spring tension forces the studs inward into the engaged position after they pass the shoulder. When the tool is raised the studs stop against the shoulder, preventing the tool from sliding up over the top of the probe. Once it engages the shoulder of the probe it cannot be freed until both probe and fishing equipment are recovered from the drillhole.

Jan 1, 1960

By Tom Bilson

TO recover the remaining ore tonnages along the south side of the Inspiration orebody, the company began open-pit operations in early 1948 in addition to underground mining. Due to the differences in elevation between the orebody and the existing ore handling and treating plants, the truck haulage operation is up hill. Road grades were established at 7 pct maximum.

Jan 8, 1951

By T. G. Madgwick, W. Calder

Production of petroleum increased again during 1929, thus maintaining the steady growth inaugurated by the bringing in of Royalite No. 4 in Turner Valley, Alberta, towards the end of 1924, prior to which a decline over a number of years had been experienced. The growth has been confined to the Province of Alberta, the older production in New Brunswick and Ontario showing declines, although in the latter case considerable activity in the search for new gas structures was maintained and during the last six months two wells were brought in, one at Howard in the Trenton at a depth of 1250 ft., giving 5,500,000 cu. ft., and the other at Tilbury in the Guelph or Salina at 750 ft. giving 9,000,000 cubic feet. As has been the case during the past five years, interest in the search for structure and in the following up and development of areas already recognized has centered in Alberta and adjacent portions of Saskatchewan. This was due in the first instance to the striking of wet gas in the Palaeozoic limestone (Madison) of Turner Valley, some 30 miles south of Calgary, in Royalite No. 4 in October, 1924. The bringing in of other wells of similar importance late in 1928 and in the spring of 1929 which extended the productive area 3 miles southwards led to greatly enhanced drilling activity throughout the structure and adjacent areas and in other parts of Alberta. As a result good strikes of heavy crude oil have been recorded during the year at Ribstone, Oyen, Skiff and Coutts, in each case at moderate depths and in sufficient quanitity to justify prolonged testing. The prospects of a satisfactory production of this grade of oil are very encouraging. Actual oil production in the west is still confined to the Province of Alberta and for all grades of oil totaled 997,359 bbl., which compared with previous years shows a gratifying increase. To this increase the naphtha obtained from the wet gas of Turner Valley has proved the principal contributant, heavy crude also showing an improvement, while the light crude, the product of the Cretaceo-Jurassic sands overlying the Paleozoic of Turner Valley, remains unchanged. This is largely owing to operators casing off these sands in their endeavor to reach the limestone, but, there is evidence that in future more attention will be paid to

Jan 1, 1930

By Moshe Sheinkin, Burke O. Trafton

This paper describes the use of a computer in analyzing the expected return on a mining venture. The computer program is designed to incorporate all aspects of a mining project, including the mine, mill, smelter, and refinery. Data input may consist of the operating variables in each phase such as the mining rate, grades, reserves at the mine, and the technical operating characteristics of the mine, mill, smelter, and refinery. Detailed tax computations are shown for a domestic operating company, for a foreign company and for a foreign subsidiary. In addition, the use of the various options that are available such as expense write-offs or deferments to create tax credits during preproduction years are considered, and its effect on the DCF. The program is also constructed to accommodate changes in metal prices, and escalation of capital requirements and operating costs. Output consists of profit and loss statements for entire projects using different methods of depreciation, cash flows, discounted cash flows, net present value and returns on investment. Returns on investment are computed for equity investment, total investment, and total investment less tax credits. Allowances are made for bank and guaranteed loans. Additional financial statements can be made for the following: a) A mine-mill segment with a concentrate selling schedule b) A mine-mill-smelter complex with a smelter product selling schedule c) Profitability of the smelter separately d) Profitability of the refinery separately

Jan 1, 1969

By M. L. Requa

This paper is abstracted from the report of the Appraisement Committee of the Independent Oil Producers' Agency, of which the writer was Chairman. The other members of the committee were M. V. McQuigg and R. S. Haseltine. To Thomas Cox, engineer in charge of the investigation, and to his efficient staff of assistants, is due the credit for the detail work necessary in carrying out the plan of the Committee. It treats only of the valuation of the lands, wells, and piping, without going into details of equipment and other features. It was recognized, early in the operation, that the value of oil lands was the value of oil to be extracted, and marketed, less the costs attendant thereon. Referring this back to the costs in cents per barrel, it became obvious that surface improvements, absolutely necessary in the production of oil, from wells then drilled; had no separate and independent value aside from the value of the land, but that any excess equipment, not necessary for the production of oil from present wells, such as drilling tools, well casing, etc., should be given a present condition value. In valuing the properties of the Independent Oil Producers' Agency, the Committee has considered the following facts: 1. That from each property there will ultimately be. produced a certain total quantity of oil. 2. That in the production of that oil a certain total quantity of money will be expended. 3. That a certain total amount of money will be received from the oil. 4. That the total net receipts will be the total gross receipts less the cost of development and production. 5. That the present value of the net receipts must be such an amount that when invested by a purchaser it will be returned with 8 per cent. interest additional during the life of the property.

Jan 2, 1918

By Alexander Knoll, Dwight L. Baker

THIS paper is a report on work undertaken to investigate the results and conclusions of Ravitz and Porter1,2. that galena freed of surface oxidation products and lead carbonate ("clean" galena) is water-repellent, and that the action of xanthates in flotation is the action of a cleansing agent, enabling oxidized galena particles to expose a pure lead sulphide, water-repellent surface. The apparatus, in construction and use, was essentially that of Ravitz and Porter. The only significant modification introduced by the present authors was the substitution of a three-necked flask for the flotation cell as the "reaction vessel." Our procedure was to place 50 grams of freshly ground, minus 200-mesh galena in the reaction vessel, sweep out all molecular oxygen from the system with oxygen-free nitrogen, and proceed to wash the galena surface free of its oxidation products with repeated small portions of (I) ammonium acetate (500 c.c. of water, 200 grams of ammonium acetate) or (2) ammonium chloride, hydrochloric acid (2 liters containing 200 grams of ammonium chloride and 25 c.c. of 1.18 sp. gr. hydro chloric acid). The galena was next washed with many 100-c.c. portions of oxygen-free, distilled water. The galena was finally considered free of soluble salts when wash water that had been in contact with the mineral for at least 48 hr.* gave negative tests for: (I) lead ion with sulphide; (2) chloride with silver ion; (3) acetate with cuprous chloride, sodium chloride; and (4) ammonium ion with Nessler's reagent. Next 500 c.c. of potassium ethyl xanthate solution, free of dissolved oxygen, was run onto the "clean" galena particles. For this system there were determined: I. The wetting properties of the clean galena particles by shaking the reaction flask and noting the degree of mineral collection at the liquid-air interface. This was, of course, simply a qualitative test, but it proved adequate for our purpose. 2. The removal of xanthate ion from the potassium xanthate solution on being shaken with the "cleansed" mineral. Xanthate concentrations were determined by iodine titration according to the methods of Taylor and Knoll.3 3. The pH of the xanthate solution after having been shaken with the "cleansed" galena. The pH was determined colorimetrically.4 The results of five experiments of the type mentioned above are given in Table I.

Jan 1, 1941

By George Evans

DURING the past ten or twelve years, the average reader of newspaper and magazine articles has been led to believe that enormous deposits of high-grade coal exist in the northland and that these can be mined for practically nothing. But much of the reputed glitter and attractiveness of Alaskan coals disappears when viewed at close range. Many areas of coal-bearing rocks are widely distributed geographically from Cape Lisburne, on Bering Sea, to Admiralty Island south of Juneau. Bituminous coal is found at Cape Lisburne, on the Bering Sea, at Five Finger Rapids on the upper Yukon, and at Herendeen Bay and Chignik Bay; lignite is found on the Kobuck River, along the Yukon River from points near the mouth to Tonakat, near Rampart, at Dawson, on the east shore of Cook Inlet, and in the Tanana Valley, 50 mi. south of Nenana. The Susitna and Matanuska Valleys contain coal ranging from lignite to anthracite, and in the Bering Lake district, there are coals ranging from semi-bituminous to anthracite. No effort will be made to describe all of these fields, but the writer wile confine himself to the four principal fields, namely, the Nenana field, in. the interior of Alaska, tributary to the Fairbanks district; the Matanuska, field, in the Matanuska Valley; the Kachemak Bay field on the east shore of Cook Inlet; and the Bering River field, east of the mouth of Copper River.

Jan 2, 1921

1. Healthy and active Local Section organizations, are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should.

Jan 1, 1939

The Keweenaw Peninsula in the Upper Peninsula of Michigan is plagued with abandoned prospectors' test pits and mine shafts, the result of exploration and operation of mines for over 100 years. The Fort Wilkins State Park in Keweenaw County alone has three open prospectors' pits within its boundaries, protected by wooden fences and maintained by the (Michigan State Conservation Department as a tourist attraction.

Jan 1, 1967

By L. D. Wooddy, Robert Moscrip

The simultaneous solution of the volumerric balance and the unsteady-state equation has been used for several years to make performance calculations for combination drive reservoirs. This method makes possible the calculation of volumetric changes of fluids in the gas cap, oil zone, and aquifer which occur as a result of withdrawals and reservoir pressure changes. It does not provide a means for the determination of reservoir fluid distribution changes corresponding to these vollrmetric changes. A knowledge of the fluid saturation distribution in the reservoir at various stages of depletion is important for the determination of the efficiency of gas and water as oil-displacement media and, therefore, for the reliable predicrion of ultimate oil recovery. To provide this knowledge, the displacement equations are solved simultaneously with the volumetric balance and unsteady-state equations. The described calculation procedure has been used satisfactorily to analyze the past performance and to predict the future behavior of combination drive reservoirs under both primary and pressure-maintenance operations. INTRODUCTION The three basic mechanisms by which oil is displaced from a reservoir are: (1) dissolved gas drive—the displacement of oil by the expansion of liberated solution gas, (2) water drive—the displacement of oil by water which enters the oil zone from the aquifer, and (3) gas cap drive—the displacement of oil by gas which ex- pands into the oil zone from the gas cap. The action of gravitational forces may be effective in increasing the efficiency of the basic drive mechanisms. Gravitational forces favor the segregation both of gas and oil and of oil and water, thus tending to shorten the transition zone between oil and displacing fluids. Most reservoirs produce under the influence of a combination of these drives and are designated "combination drive reservoirs". Fig. 1 is a cross section of a typical combination drive reservoir. A calculation procedure for analyzing the performance of combination drive reservoirs has been developed by combining the displacement equations' with the volumetric balance equation' and the unsteady-state equations. The pressure-production performance and the positions of the gas-oil and oil-water contacts are calculated for several stages of reservoir depletion by solving these equations simultaneously, thus affording a basis for: 1. Determining instantaneous and ultimate oil, gas, and water production under various operating conditions. 2. 'Establishing a maximum efficient rate of production, 3. Determining the advantages of pressure maintenance and unitization, and 4. Designing surface installations necessary for primarv and pressure-maintenance operations. DEFINITIONS The calculation procedure for combination drive res-

Jan 1, 1957

By T. A. Rickard

From time immemorial the fissure-vein has been held the simplest type of ore-deposit. The prominence given to it by Cotta and his disciples, from their study of the mines of the Erzgebirge, is impressed upon technical literature; and, in consequence, the ores which carry the valuable metals have been supposed to occur mainly in fissures, cleaving the rocks in diverse directions, and the noblest type of vein has been deemed that which cut across the country independent of its structure, whether evidenced as bedding, foliation or cleavage, and which was identified with rents produced in the rocky crust of the earth. As so conceived, the vein was a fissure filled with ore, extending through the country for a varying distance, and continued downward to a depth more or less proportionate to its longitudinal extent. The vein-material was bounded by an encasement of rock, and those immediate surfaces which limited it on either aide were called " walls." These primary conceptions have become modified by the experience of modern mining in widely separated regions. The study of lode-formations has led to the recognition of notable departures from the supposed normal structure of the veins of Saxony and Cornwall, the two classic homes of early economic geology. Typically the walls of a vein are conceived as parallel rockplanes enclosing the ore; the upper one being called the " hanging-," and the lower the "foot-wall."* Walls are rarely alike. Even where a vein traverses a homogeneons formation, such as a massive crystalline rock, it is usually found that the surface which bounds it underneath

Jan 1, 1897

The early records of coal in Kentucky by Walker and Gist have already been mentioned. Thomas Hutchins was aware of it in 1778, or perhaps several years earlier, as in writing of the Buffaloe, now Green, River, he said, "several persons who have ascended this River, say, that Salt Springs, Coal, Lime and Free Stone etc. are to be found in a variety of places."1 The next record found is an entry to Ellis and Marshall, of 878 acres on Coal Bank Creek, in the, then Fayette County on July 14, 1784.2 The settlement might have been made, or the name given, some time before. Hermeline, in 1783, mentioned iron ore and coal on the Green River,' although he had not been west of the Susquehanna River; his knowledge of coal might have come from Hutchins, although the latter made no mention of iron in that locality. In November 1790, coal was mined on Sturgeon's Creek in Lee County and floated in three barges down the Kentucky River to Cleveland's Ferry, where it was hauled to Lexington. The results were not equal to the expectations, and it was 1793 before the experiment was. repeated 4 In 1791, the estate of Samuel Wharton advertised for sale 31,000 acres "in the county of Jefferson, on the North Side of the Green or Buffaloe river, in the State of Virginia."5 In November 1795 three patents were issued for land in the then Lee County, aggregating 130,000 acres. These patents cover much of Harlan County. The descriptions of these surveys mention passing stone coal. on Rough Branch of Martin's Fork, a "great deal of stone coal" on Blacksnake Branch of Pucketts Creek, and "a quantity of stone coal" probably on Crummies Creek.6 Jedediah Morse, in The American Gazetteer, 1798, said that in Kentucky "in many places there are appearances of potter's clay, and coal in abundance." It is possible that shipments may have been made from near

Jan 1, 1942

SEC. 1. The membership of the Institute shall comprise six classes, namely: 1. Members; 2. Honorary Members; 3. Senior Members; 4. Associates; 5. Junior Members; 6, Rocky Mountain Members. All shall be equally entitled to the privileges of membership, excepting that no member of any class whose residence shall be outside of the United States of America, except those residing in Mexico and Canada, shall be entitled to vote. SEC. 2. Members: A person to be eligible for election or transfer into the class of Member must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy, or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. This shall not apply to Rocky Mountain members. SEC. 3. Honorary Members: Each candidate for Honorary Membership must be recommended by at least ten Members and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of the Directors present; provided, however, that the number of Honorary Members shall at no time exceed twenty. Such election shall automatically act as a transfer of such member from any other class of membership to which he may belong. SEC. 4. Senior Members: The Directors may in their discretion place on the Honor Roll of Senior Members and transfer from any other class of membership other than Honorary Membership the name of any Member or Associate who has reached the age of seventy years and who has paid dues for thirty years, and for good reasons in • special cases may vary the age or number of years. SEC. 5. Junior Members: A person to be eligible for election to the class of Junior Member must be qualified through education or experience to hold a subordinate position in engineering, mining, metallurgical, geological or chemical work. He shall be not more than twenty-seven years of age at the time of election. The rights of the present Junior Associates shall continue until the same expire by limitation of time. SEC. 6. Associates: A person eligible for election or transfer into the class of Associate shall be one, who, in the opinion of the Committee on Admissions and the Board of Directors, is suitable for such election or transfer by reason of his interest in or connection with mining, geology, metallurgy, or chemistry. SEC. 7. Rocky Mountain Members: Membership in a special class of life memberships without annual or other dues and without right to receive the printed literature distributed to other members or the right and privilege of wearing the official badge of technical members, is given to all members of the Rocky Mountain Club at the time of consolidation. These special Rocky Mountain memberships shall be claimable by any member of the Rocky Mountain Club, not already a member of the Institute,

Jan 1, 1929

By S. Frederick Ravitz

IN recent years, two theories of the mechanism of flotation have received a great amount of attention. One of these is Ostwald's theory of linear flotation,1 according to which most collectors contain three active groups: a hydrophilic or water-loving, a metallophilic or mineral-loving, and an aerophilic or air-loving group. Under the action of these three groups, Ostwald considers a single ring of collector molecules at the three-phase air-liquid-mineral boundary sufficient to bring about the flotation of the mineral particle. Siedler, Moeller and Reddehase2 objected to this theory immediately after it was presented, but most of their objections were answered by Ostwald.3 Very recently, however, Wark and Cox4 have more adequately criticized this theory, and their criticism makes its validity appear doubtful. The other important recent theory is the "chemical" theory of flotation, proposed by Taggart and his coworkers,5 who maintain that "all dissolved flotation reagents, which, in flotation pulps, either by action on the to-be-floated or on thenot-to-be-floated particles affect their floatability, function by reason of chemical reactions of well recognized types between the reagent and the particle affected." In general, they appear to consider most flotation results to be brought about by purely chemical reactions between the collectors and the products of oxidation present

Jan 1, 1933

By V. T. Stringfield, H. H. Cooper

ONE of the earliest investigations of ground water in Florida was made in 1513 when Ponce de Leon arrived at St. Augustine in search of the Fountain of Youth. The history of the development of the water resources of the State shows that the large artesian reservoir that underlies Florida was discovered in the latter part of the last century. Part of that history is given by L. C. Johnson' who states that the first successful artesian well in Florida was drilled at St. Augustine between 1880 and 1882. After the City of Jacksonville failed to obtain a flow of artesian water at a depth of nearly 400 ft and abandoned the drilling, R. N. Ellis, City Engineer, and L. C. Johnson, using Johnson's knowledge of the geologic structure of the artesian reservoir, estimated correctly that artesian water could be obtained at a depth of about 500 ft. Thus began the development of the large artesian system in the northeastern part of the State. In 1908, the Florida Geological Survey issued its first report on the ground water of central Florida. More recent reports give the results of investigations that have been in progress in cooperation between the Florida Geological Survey and the U. S. Geological Survey since 1930. As a result, the ground-water geology and hydrology of Florida are now so well known that ground-water problems such as confronted early investigators no longer exist. However, new problems arise and new discoveries are made as the demand for more ground water increases with the development of the State. Water-Bearing Formations Descriptions of the geologic formations and a map showing their distribution at the surface are given in a recent report by Cooke.' The geologic formations that yield the ground-water supplies in Florida represent only a small part (about 1000 ft) of the total thickness of the sedimentary rocks (more than 15,000 ft) that underlie Florida. The water-bearing rocks that yield fresh water include more than two dozen formations that range in age from Eocene to recent. The Eocene formations, which consist chiefly of limestone, are the oldest and the deepest of the formations in Florida that yield fresh water to wells. In 1944, on the basis of a study of the foraminifera, the Applins -ivided the limestone of Eocene age into six formations, which are as follows, from top to bottom: Age or group Formation Jackson Ocala limestone icAvon Park limestone Claiborne -j Tallahassee limestone aLake City limestone Wilcox Salt Mountain limestone xOldsmar limestone The Ocala limestone and the underlying formations of Claiborne age, along with some of the overlying limestone of Oligocene and Miocene age, constitute the principal source of water in Florida and southeastern Georgia and generally may be regarded as forming one artesian aquifer or water-bearing unit. This aquifer is referred to in this paper as the Floridan aquifer, a name proposed by Parker.' In part of Seminole County alone more than 1000 flowing wells yield water from the Floridan aquifer. A yield of 6500 gpm, or about 9.5 million gal per day, by natural flow from a well penetrating the aquifer at Jacksonville, Florida, was observed in 1942. A yield of about 7000 gpm by natural flow was reported for a well 1390 ft deep at St. Augustine in 1887. The largest yield reported from a pumped well penetrating the aquifer is 7500 gpm, or about 10.5 million gal per day. The aquifer is also the source of some of the large springs, such as Silver Springs, whose discharge, according to measurements made by the U. S. Geological Survey, has ranged from 526 to 1350 sec-ft, or from 340 to 872 million gal per day. The top of the Ocala limestone, as represented by contours in Fig. 1, indicates in a general way the geologic structure of the formations that comprise the Floridan aquifer. The Ocala is at or near the surface in the areas represented by shading in the northwestern part of the peninsula and also in an area in western Florida adjacent to Alabama and

Jan 1, 1952

By R. W. Raymond

In a paper on the Divining-Rod (Transactions, xi., 411), presented at the Boston meting, in February, 1883,I suggested, among other signs of which the skilled prospector might consciously or unconsciously avail himself in the search for springs of water or mineral deposits, the presence of particular grasses or shrubs, and the general appearance of the flora. There are not wanting, in the literature of our art, indications that greater attention was paid to such signs in ancient days than at present. It is the tendency of a scientific age to ignore, or regard as superstitious, what cannot be classified or explained. But the acute though unscientific observation of earlier times often, doubtless, accumulated facts which it would be worth our while to re-examine. It is highly probable that the mining prospectors of the sixteenth and seventeenth centuries, to go no further back, were close students of nature, and knew, though they could not explain, and, for reasons of private gain, would not communicate, many curious and significant facts. We can generalize better than they could; but for that very reason we are, perhaps, their inferiors in observation. They let nothing pass, because all things were equally significant to them. We take wider views, and miss more. And, no doubt, there still exists among practical millers, prospectors,, hunters, Indians, etc., an unwritten.

Jan 1, 1887

By Robert C. Stephenson

In 1954, a year when general industrial production declined, it is significant that industrial mineral products continued in high demand. Phenomenal growth of the cement industry, increase in filler-fibre markets such as for asbestos and diatomite, expansion of the gypsum industry, and the increasing production of agricultural raw materials all illustrate the vitality of industrial minerals fields. Pioneer development of new industrial raw materials-wollastonite as a current example-requires keen foresight, hard work, and tremendous intestinal fortitude. The present-day requirements of industry for rigid quality control and uniformity of raw materials have resulted in highly specialized

Jan 3, 1955

By A. H. Shoemaker

THE shutdown of Homestake by Government order L-208, with its consequent disruption of a very stable and trained working force, coupled with postwar inflation and the coincidence that a mining depth had been reached that posed problems of ventilation, access to exploration areas, and choice of mining methods that would be applicable to zones of greater rock pressures made a very searching analysis of every phase of Homestake's operations a necessity. Any changes to be made had not only to meet the problems of deeper mining but also had to provide greater efficiency so that the mine might operate at a substantial profit until such time as a gold price adjustment might be forthcoming that would offset post-1945 inflation. Geology and Mining Situation The Homestake mine lies in the northern Black Hills in an area of Pre-Cambrian rocks exposed by the erosion of the paleozoic formations which covered the Black Hills. The Pre-Cambrian rocks in the vicinity of Lead comprise metamorphosed sediments with a total thickness of about 20,000 ft. The oldest formation, the Poorman, is ankeritic carbonate schist. The next oldest, the Homestake formation, host rock for all Homestake orebodies, is a siliceous iron-magnesium carbonate schist. The younger formations are dom-inantly argillaceous with some quartzites. Tertiary intrusive rocks cut all formations. The Pre-Cambrian rocks have undergone extreme isoclinal folding. Superimposed on this intricate folding are zones of shear folding which cross the isoclinal folds at small angles. The Homestake orebodies are pipelike replacements of the Pre-Cambrian Homestake formation where certain cross folds intersect some earlier isoclinal folds. These orebodies plunge flatly to the southeast at variable angles locally as steep as 45". The orebodies are replacement areas where numerous vein quartz of irregular shape have formed with surrounding zones of chlorite alterations containing disseminated sulfides and metallic gold. Where the numerous individual quartz veins with the sulfide and gold-bearing alteration zones are close together, large irregular orebodies with a roughly elliptical plan outline result. These ore zones may be more than 200 ft wide and 700 ft long in plan area. They have followed down the plunge of certain severely folded structures with great persistence. Two vertical operating shafts, the Ross and Yates, serve the mine, one with rope capacity to reach the 4850 level, the other to the 5000 level.

Jan 1, 1959

By H. R. Hanley, Charles Y. Clayton

ONE of the most important contributions to the art of electrolytic zinc production has been the aluminum cathode. This has been used in all major production since its commercial development in 1916. The literature is replete with important contributions, some of which may have been replaced by better ones, but thus far there appears no other metal to take the place of aluminum as cathode material. Credit for this innovation goes to Sherard Cowper Coles, of England. When experi¬menting on the extraction of zinc from Broken Hill ore at Hayle, Cornwall, in 1893, he introduced the aluminum cathode, and in 1895 obtained British Patent No. 20073. The reason for this dominant position of aluminum as cathode material in zinc sulphate electrolytes is its unique surface, to which electrodeposited metals usually do not tightly adhere. The metal must be of high purity for best results. It is possible to develop a starting-sheet method by which thin electrodeposited sheets of cathode zinc are made and stripped from a smooth aluminum plate. Such thin sheets of cathode zinc may be used as are the copper sheets in standard electrolytic copper-refinery practice. However, complications arise because of extreme warping of the zinc starting sheet after a few hours of deposition, and thus special arrangements must be made to compensate for this abnormality. Reasons advanced for the ease with which deposits may be stripped from the aluminum surface are: (1) presence of a permanent oxide coating on the metal, (2) failure of aluminum to alloy with the deposit, (3) differences in coefficient of expansion, (4) high position of aluminum in the electromotive series of metals. Of these reasons for nonadherence, which may have some application in general deposition, probably the oxide coating has the greatest bearing on the subject of zinc deposition. Adherence of zinc deposits has occasionally had serious effect oil tonnage and production costs. Opinions have differed as to the specific

Jan 1, 1938