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By J. Kunze, R. Degal

During the last 100 years, the submerged arc furnace has been one of the most amazing diversified melting units. These furnaces have found their application in more than 20 different main industrial areas such as iron, ferro alloy, chemical industry, lead, zinc, copper, refractory, titanium oxide, recycling, phosphorus etc. Such an evolution was only possible because of tremendous efforts in research and development and due to the large range of design solutions. The worldwide strong competition also forced the industry and plant suppliers to develop highly efficient, economically balanced units in optimized sizes and with long lifetimes, to adapt to the market conditions. Regarding the environment, the plants improved significantly in terms of water treatment plants and off-gas treatments as well as on site recycling units. This paper will give a short overview regarding the history of the furnace and the latest developments in today?s main application fields: ferro alloys, non-ferrous, special application and recycling. In addition new activities in research and developments are briefly discussed.

Jan 1, 2004

By Robert Hopler

DESCENT INTO A COAL MINE From “The Playbook of Metals, including Personal Narratives of Visits to Coal, Lead, Copper, and Tin Mines,” by John Henry Pepper. Published by Routledge, Wa rne, and Routledge, London, 1862 ENGINEERING NEWS New Yor k January 22, 1903 THE BEGINNING OF THE END OF DYNAMITE. In another part of this issue we have reported the results of some test results made upon one of the safety powders. It will pay every c o n t r a c t o r, miner, or user of explosives in any form to carefully re a d the article re f e r red to. Dynamite has done a gre a t work in the service of man, as did black powder before it; but its i n h e rent dangers are admitted by all and are proved by the long list of deaths and injuries, and destruction to property which annually occur through its use. Why should we continue to use an explosive that annually kills and maims hund reds of men, when others are available which are equally powerful, no more expensive and far less liable to accidental discharg e ? Dynamite when first manufacture d is pure and comparatively safe; but most unfortunately it does not always stay pure; it “rots,” and then it is exceedingly dangerous. More than this, the explosive part of dynamite is a liquid, nitro - g l y c e rine, which is absorbed or soaked up by sawdust, wood pulp or the like. So long as this liquid nitro - glycerine remains pure and remains “soaked up,” or absorbed t h e re is little danger. It has been found, however, that the nitro - g l y cerine leaks under certain conditions. During thawing it fre q u e n t l y leaks out of the stick, or if it becomes wet the water causes the n i t ro-glycerine to leak out. In either case free liquid nitro - g l y c e r i n e escapes, and in that free state it may be exploded by any very slight shock. Nor is this all, if a stick of frozen dynamite be bro k e n a c ross it has been found by tests that the frozen nitro - g l y c e r i n e w h e re thus broken is very sensitive to shocks afterward .

Jan 1, 2004

By T. H. Oxnam

INTRODUCTION. THE predominating value of the ores now being treated by the Palmarejo and Mexican Gold Fields, Ltd., is silver, although some gold is also carried. The present method of treatment consists of wet-crushing and concentrating, followed by the cyanidation of the unroasted sands and slimes. The sands are treated by leaching and the so-called accumulated slimes by a system of agitation and decantation. It is only within very recent years that the cyanidation of unroasted silver-ores has been commercially successful. In fact, at the time operations were begun at the cyanide-plant at Chinipas, February, 1902, I knew of no other leaching-plant treating similar ores successfully. The cyanide treatment of the Palmarejo ores differs but little from the ordinary practice in cyaniding gold-ores; and perhaps but little, if any, new information concerning the metallurgy of silver is to be gleaned from it. PALMAREJO MINE. The Palmarejo mines are located in the southwestern part of the State of Chihuahua, Mexico, on the foothills of the Sierra Madre mountains, at an elevation of 3,200 feet. The mills, 12. miles distant, are situated on the Chinipas river, near the town of Chinipas, which is about 150 miles northeast of Agiabampo, on the Gulf of California. Supplies are shipped via this port as this route is the best and most direct to the property. The ore-bodies in the Palmarejo mines have been deposited. along a series of rock-fractures, caused by an intrusion of eruptive rock. The most important of these fractures or fissures, both in width and value, are the Prieta and Blanca veins, which.

Jul 1, 1905

By AIME AIME

WHEN "Chief" Buehler in mid-September set out on his official 10,000 mile swing-around-the-circle visiting Local Sections he decided not to tell his audiences how to organize and operate a state geological survey. As the director for 28 years, of the Missouri Bureau of Geology and Mines (which, he concedes, is the best in existence) lie could have done this to good advantage; but he preferred to discuss affairs of the Institute. In 25 speeches made to member and student groups, he dwelt on sonic or all of the following phases of activities. He stressed the vital importance of the Local Sections in providing the opportunity for members to associate under pleasant auspices with others in their profession. The benefits of Institute membership he classified as tangible and intangible. Of the two lie felt that the latter were more important. A man's progress in his profession depends in large measure upon a broad acquaintance and friendship with others. The Institute is incomparably the best medium for meeting fellow engineers. The primary, function of the new enlarged Membership Committee is to obtain a comprehensive list of engineers eligible to be members, always hearing in mind that the standards of membership must not be lowered in any degree. These men are to be invited by individual letter to apply for membership. Whether they become members or not is of less importance; but it is vital that no qualified man should be outside the fold for the reason that membership had never been suggested to him. Dr. Buehler emphasized repeatedly his feeling that the younger man that had never had Institute membership brought specifically to his attention had been cheated:

Jan 1, 1935

By D. A. Trotter, G. J. Goddard

"This paper describes a method of deciding on various design parameters for a sublevel caving layout. Layout design curves are obtained from the output of a computer optimization program. The program uses mathematical relationships derived from the theory of gravity flow of material to optimize the large number of interdependent design variables which are involved.IntroductionIn the design of an efficient sublevel caving mining system, a large number of interrelated variables need to be considered. Although many papers discuss individual variables, very little exists in the literature to show how these variables interact to achieve optimum results. This can lead to trial and error in sublevel caving design, which can prove costly, particularly because sublevel caving is a mining method which requires integration with sublevels above and below. With no pillars being left, experimental stopes cannot be isolated for study. Unfortunately, the complexity of layout design and the costs associated with trial and error have caused many planning engineers to choose more tried and tested mining methods.Sublevel caving works best to extract low-value ore surrounded by incompetent rock. All phases of the mining method can be highly mechanized, allowing low operating costs and high production rates. Good safety records are achieved, as workers are always in 'good' ground and the method is regular, making it comparable to an industrial process."

Jan 1, 1981

By Jerry C. Tien

Mining in China dates back at least 4,000 years. Today, with no less than 103,000 metal/nonmetal mines and between 40,000 to 80,000 coal mines, China’s mining industry is undoubtedly the largest in the world. Despite improvements in recent decades, seemingly endless mining accidents continue to make the news. Official coal mining deaths were 6,702 in 2003, and 6,027 miners died in 2004; actual figures may be much higher. Added to these were the 2,699 deaths in the metal and nonmetal industries. Most of these accidents were due to CH4 (methane gas) explosions and fires as a result of inadequate mine ventilation de-sign or practices. A good portion of these accidents occur in small, privately run and often technically illegal mines. During the past 10 years, the Chinese government has attempted to crack down on small and often technically illegal mines without much success. The number of accidents and associated fatalities has not significantly reduced. However, there appears to be a new urgency in China’s efforts to step up mine safety in the country. After its worst reported mine disaster in more than a half century, the government quickly paid reparations to families, suspended high-level officials in charge and announced additonal reforms. One of those was the elevation of the central government’s work safety office to cabinet-level status. There has been increased transparency in reporting and investigation of mine accidents and disasters in recent years. There has also been an increase in public criticism by labor leaders concerning the neglect of mine workersafety.1 This article examines the causes of China’s many mining accidents, current legal and enforcement structures, respective mining health and safety related laws and regulations, recent mining industry developments and the latest effort to curtail small mining operations.

Jan 1, 2005

By Julián M. Ortiz

Uncertainty quantification of a spatially distributed variable at any scale can be handled through geostatistical simulation. Large computation time, storage, and post-processing of the realizations are required to obtain a final assessment of block uncertainty. Multi-Gaussian kriging is a flexible alternative to simulation. The idea is to compute the conditional distribution of uncertainty after normal score transformation of the original samples. Under the multi-Gaussian assumption, all marginal and conditional distributions are Gaussian, hence fully defined by their mean and variance. The parameters of the conditional distributions are obtained by simple kriging and can be back-transformed to the original units of the variable of interest. An estimate and any summary of uncertainty can be easily retrieved. The main disadvantage of performing multi-Gaussian kriging is that change of support is not straightforward, that is, calculating uncertainty of block grades. We propose a methodology to overcome this limitation by considering a matrix simulation to generate multiple probability fields. Each probability field is used to draw spatially correlated point values from the point-support conditional distributions, and multiple realizations of the average can be obtained. This permits the calculation of the average over the block and its uncertainty. These blocks may correspond to selective mining units or to volumes from longer production periods relevant for engineering decisions. They can even be disjoint blocks, such as when several faces are mined at the same time. POSTMG, a Fortran program to perform these calculations, is described and a case study is provided.

May 1, 2004

By M. Salimov, J. Sattarvand

The conventional visualisation method of remote equipment is through the installation of one or more cameras on the machine, and sending a live feed to the operator’s flat display. However, the performance of the teleoperation can be enhanced using better visualisation through virtual reality (VR). This paper presents the process of the design and manufacturing of a robotic platform that will be used in the next phase of the project for a VR-assisted teleoperated excavator. The robot consists of a loading boom and arm arrangement installed on the undercarriage of a CAT300-9D. All hydraulic cylinders are replaced with electric actuators, and crawling motors are substituted by electric motors. The pieces of the boom and the arm, as well as the bucket were designed in Autodesk Inventor, and manufactured from aluminium sheets using a desktop and CNC machine. Parts are joined by pins and welding as needed. An Arduino-based control system is developed for the robot, and motor controllers are used to convert the power commands from the microcontroller to the high-amperage actuators. The control system is capable of communicating with a wireless Play Station controller to operate remotely. The manufactured robotic excavator is planned to be utilised in multiple autonomy research projects.

Sep 1, 2021

By J. -F. Lessard

Most underground mines rely on ore pass systems to ensure the transport of ore and waste. The design and operation of ore pass systems often rely on past experience, which is often anecdotal and at times contradictory in nature. This paper summarizes the current practice in Quebec underground metaliferous mines. The information was collected during a series of site visits in ten underground mines. The database includes information on ore pass configuration, support, materials transited, and overall ore pass performance.

Jan 1, 2006

By M. C. Makepeace

"It is the objective of designed experiments to obtain more information for less material and process cost than can be obtained by traditional experimentation. In this paper, the fundamental concepts on which the statistical design of experiments is based are briefly re-viewed according to the following outline: The Experiment The Design The Analysis Two simple 2"" factorial experiments are presented as examples."

Jan 1, 1967

The Phoenix mine on the Mararoa Reef at Norseman, Western Australia, provides an outstanding: AUstralian instance of the recurrence of payable ore beneath the bottom of an abandoned mine, and an interesting and instructive example of the development ofideas with regard to ore recurrence in a particular district. The Mararoa Reef is the most productive of several hypothermal goldquartz vains in pre-Cambrian basic volc81olics which strike northsouth and dip on the average, 45 degrees east. The Phoenix minewas abandoned at 500 ft. vertical depth after producing 342,000 tons of 9.9 dwt. recovery grade (equivalent to nearly half of the total production of the Norseman field) from a 2,500 ft.. long, horizontally disposed oreshoot, which is reported to have had an ore outcrop only 30 ft. in length.Interest in the field was revived in 1933, and by 1941 new ore mined and developed on the Mararoa Reef by Central Norseman Gold Corporation N.L. amounted to approximately 700,000 tons of 6.7 dwt. recovery grade. In the same period another oreshoot of similar size and grade was developed by Norseman Gold Mines N.L., south of the old Mararoa company's site. As shown by the plans, the ore occurs in discontinuous shoots. The intervening area of shear is poor in quartz as well as in gold. Geological work on behalf of Western Mining Corporation Ltd., and Central Norseman Gold Corporation N.L. has been in progress in the mine and in the field more or less continuously from 1913 to 1941 and again since 1946. This paper describes the successive advances in the understanding of the exploratory problem up to late 1941, to which several investigators have contributed. It is published by permission of the Board of Directors of Central Norseman Gold Corporation N.L., owners and operators of the Phoenix and other mines.Development of the Prospect.In 1933 Western Mining Corporation acquired an option over the Phoenix property and adjacent leases. H. E. McKinstryl visited the mine and recognised that the ore occurred primarily on the flatly dipping sections of the vein, as distinct from the steeply dippingsections, in a wide shear zone with reverse movement. Many of the flatly dipping fractures were seen to exhibit tension phenomena and to link one shear plane to the next below on the footwall side. The flat links carried much more quartz than the steeper shears.Later, H. J. C. Conolly, assisted by J. D. Campbell, examined the prospect and by contouring the vein with reference to an inclined...

Jan 1, 1950

By G. H. Lind

New South Wales has a successful history of pillar extraction stretching back more than 60 years. Various methods of pillar extraction ranging from the rib pillar methods (such as the Wongawilli system) to the more recent pillar stripping techniques (similar to those used in the USA) are discussed in this paper. These discussions are based on the experiences of the author stemming from a recent research tour of seven underground pillar extraction operations in New South Wales as part of the Coaltech 2020 collaborative research initiative. Some operational issues of each site visited are presented before some general comments pertaining to the overall success of pillar extraction in New South Wales are discussed. Generally pillar extraction in New South Wales is on the decline in favour of longwalling. However, the pillar extraction that is conducted is done so along specific guidelines to ensure their success, and these are also discussed.

Jan 1, 2002

THE following notes were accumulated during the years 1905 to 1911, when the writer was employed at Stannary Hills. The writer's duty took him over the underground workings daily. In odd moments the geology of the surrounding country was worked out. As the time for this purpose was limited, many interesting points had to be left, untouched. The faulting system in the mines was of such a puzzling character that it seemed as if the geology of the surrounding district might throw some light on it. Dr Jack, in 1907, reported on these mines for the shareholders, but came to no definite conclusions. Unfortunately, the writer has not had access to this report for many years. At the time of his visit the larger develbpments in the Ivanhoe and, Kitchenen orebodies (see Fig 1, B2) were only being opened up. Mr. H. Herman mentions Stannary Hills on p 320, Proceedings Aust Inst ME, new series, No 14, and on p 326 expresses the opinion that the pipe or joint-veins (as at Irvine bank and Stannary Hills) were more valuable to follow than lodes in the granite in that district.GEOLOGY OF DISTRICTThe main feature of the area mapped is a band of altered sedimentary rocks which carry no fossils. It is a mile wide, and consists of a hard band of greywackes 200 ·t ·300 yds. wide, flanked on both sides by contorted shales which become more micaceous as the granite-area to the east is approached. The strata have a general strike of N. 30° W., with a steep westerly dip. A large area of acid intrusive rocks occurs to the west of this band. The outstanding feature of the district is a fault which cuts the sedimentary series in two, to the...

Jan 1, 1918

"Generation and removal of fines are considered in the context of the mill and classifier as a single-unit process in which grinding rates and mechanisms, mill residence time distribution, circulating load, and classifier performance all interact to effect the overall grinding circuit productivity. Required process design specifications are identified, and a computer assisted design procedure for application of hydrocyclones in closed circuit grinding is presented. INTRODUCTIONThe purpose of the grinding circuit is to carry out the size reduction necessary to suitably prepare material for the upgrading process(I) The desired product size specification being the d1st1nguishing criterion between the ""fines"" (smaller than desired product size) and the ""coarse"" fraction (larger than desired product size), the capability of the grinding circuit to perform its task effectively depends on the nature of two processes that are taking place;(a) size reduction of the coarse material, and,(b) removal of fines from the system."

Jan 1, 1984

By Alfred W. G. Wilson

THE ultimate purpose of the Chemical Manufacturer is to produce consumer products which can be sold to customers. Such production and sales can be continued only if the operations yield a profit to the manufacturer and if the products meet the requirements o the consumer--bath parties to the transaction must be satisfied. There are vast numbers of consumer products, made by chemical pro-cesses. The production of some of these ultimate products may involve the use of several intermediate chemicals, applications of few or many different processes, and the utilization, somewhere in the series of operations, of a variety of raw materials. On the other hand, some ultimate products have a very simple chemical history between raw materials and end products. There are no chemical products in use which are completely independent of the mineral industry. For many, the association is direct and obvious; for others, it may be indirect and even obscure. Analyses of the process and raw-material ancestry of a very large number of consumer products would suggest that many products are derived from Industrial Mineral products directly, that there are many in which the connection is indirect, and that there are only a few products with which industrial minerals are not in some way or other associated. The vast majority of the more important chemical products, and especially the basic chemicals from which other products are made, are directly dependent for their production upon Industrial Minerals or their derivatives. In the preceding part of this paper, for each raw material mentioned some references have been made to the leading chemical products based on this material. This, however, is only part of the story, because in most cases the consumer product can be made from any special raw material mentioned only by the use of other materials or chemicals made from them. The production of consumer chemicals is really possible only through an intricate interlocking of processes, materials, and apparatus.

Jan 1, 1940

By G. J. Hundman

Control of respirable dust produced by auger type continuous mining machines is normally attempted by water sprays from fixed nozzles mounted on the frame of the machine. In tests conducted under this contract, a 'wet auger' system was used, where the spray nozzles were mounted on the rotating auger itself. The tests were conducted at the Hunter mine of Smith and Stover Coal Company using a Jeffrey 1.00L auger miner. Operating the mining machine in the wet auger mode, it was found to produce 47 pct less respirable dust than when the fixed conventional sprays were used. On section dust levels were reduced too 3.5 mg/m3 which is equivalent to approximately 2.0 mg/m3 for a full shift portal to portal sample. The major difficulty that had to be overcome was the development of a simple reliable water transfer mechanism to get the water into the rotating augers. This was successfully achieved by the development of a water-through-the-shaft water system. This system can be retrofitted to existing machines and is available in kit form.

Jan 1, 1977

By J. W. Baker

"The Kerr-Addison mine is on the northeast shore of Larder Lake in the township of McGarry, District of Timiskaming, Ontario. It lies just south of the highway leading to the town of Kirkland Lake, 25 miles to the west.The property was first staked in the summer of 1906, by a party of prospectors led by a Dr. Reddick of Ottawa. Subsequent assessment work resulted in the erection of a 20-stamp mill in 1908. Gold from this mill was used in the first gold coins to be minted in Canada. The operation did not prove successful, however, and mining was suspended. In 1914 a consider-able amount of underground development was undertaken by the Associated Goldfields Co., without success.In 1936 Kerr-Addison Gold Mines Co. carried out large-scale sampling from four adits driven into the hillside at the mine. Results were not satisfactory, but it was decided to drill one last deep diamond drill hole from surface. The hole cut a wide section of gold ore. With this encouragement, further development outlined a large tonnage of ore, and a 500-ton mill was put into production in May, 1938. In 1939, its first full year, the mine produced 54,480 ounces of gold and 2,732 ounces of silver. By 1955 the mill had been expanded to a rate of 4,549 tons daily, and in this year 427,193 ounces of gold and 23,490 ounces of silver were produced.From 1938 to the end of 1955 the total production, from 17,473,797 tons milled, has been 3,607,462.74 ounces of gold (0.2064 ounces per ton), and 182,278.56 ounces of silver, with a total value of $131,073,037."

Jan 1, 1949

By John W. Cahn, David A. Karlyn, Morris Cohen

The massive B(bcc) — am (fcc) transformation in Cu-Zn alloys has been studied isothermally by pulse-heating the retained ß phase from room temperature to the reaction temperatures. The transformation is found to occur only in the single-phase a region of the equilibrium diagram. The massive growth rate is of the order of 1 cm per sec and is constant at each temperature, usually after a delay time of some milliseconds. The delay time depends on the reaction temperature in C-curve fashion, while the growth rate increases monotonically with temperature over the single-phase range. The absence of isothermal massive transformation in the two-phase region does not arise from slow growth rates at such temperatures, but because the reaction cannot get started there. It is proposed that the massive transjormation initiates at small preexisting a particles which have rejected zinc into the surrounding 0 matrix. Only within the single-phase region can these particles consume the excess zinc during diffusion-controlled growth and thereby accelerate to the steady-state massive growth rate. The onset of massive growth marks the end of the delay time, and the growth rate then becomes interface-controlled. These isothermal transformation characteristics explain why the usual composition range for massive-kinetic studies by quenching is so limited. The same principles can be extended to more complex alloy systems by recognizing that the single-phase region in which the massive transformation can occur may not be stable with respect to phases not participating in the reaction. MASSWE transformations are now recognized as a regular class of solid-state reactions involving no compositional change (like martensitic transformations) and no shear displacements (unlike martensitic transformations). The name was first coined by Greninger1 in 1939 to describe the coarse grains of fcc a solid solution generated via a fast reaction from the parent bcc 0 solid solution in Cu-A1 alloys. However, some 9 years earlier, phillips2 had already described a similar transformation in the Cu-Zn system. The fact that the massive a formed as a single phase during drastic quenching from the 0 region of the equilibrium diagram signified that compositional changes were precluded. and the reaction was presumed to take place as in a one-component polymorphic transition by nucleation and growth. Phillips also observed that the occurrence of the massive transformation in the Cu-Zn system was extremely sensitive to alloy composition. For example. in a Cu-37.3 at. pct Zn alloy. the ß — am (am = massive transformation product) reaction was found to predominate and was not suppressed by iced-brine quenching from the 0 region. whereas at compositions greater than 38.3 at. pct Zn the massive reaction did not appear at all. Knowledge concerning massive transformations has bee11 substantially enhanced over the years by Massalski and his coworkers; an excellent summary of his papers and the current understanding of this type of reaction has been published recently by Barrett and ~assalski." he massive transformation product grows in roughly nodular form. often with irregular boundaries but sometimes with almost planar interfaces. The latter may have simple crys-tallographic indices relative to the 0 matrix. or the indices may be complex just as in the case of mar-tensites.'1 Little is known about the existence of orientation relationships between the massive and parent phases. A striking feature of massive transformations is that the massive units start almost exclusively at grain boundaries of the parent phase and frequently propagate on a broad front across matrix grains and grain boundaries of various orientations. Because of the rapid growth rate, it is thought that the interface motion is controlled. not by long-range diffusion. but by thermally activated atom jumps across the transformation boundary.

Jan 1, 1970

By Terry L. Muldoon

This report describes development and demonstration of an upgraded stench fire warning system for underground wines. Current systems, which have been used since before 1920, release an ethyl mercaptan mixture into the mines' compressed and/or ventilation air during emergencies. Miners, when smelling ethyl mercaptan, evacuate the mine according to predetermined plans. These systems, while simple, have problems with safety and reliability. The upgraded system overcomes these problems. The system uses a different stench agent, is less toxic, less nauseating, and less corrosive than ethyl mercaptan. These combined with the feature of thiophane not reacting with iron oxides, makes the upgraded system safer and more reliable. The system also uses a combination of two simple principles: a standpipe with pressure balancing to provide a constant head, and a sized orifice to control the rate of release of the stench agent. This system enables the mine to release the agent for a longer period which provides better coverage and to ensure that miners will not be exposed to potentially toxic concentrations of the stench agent. The system is easy to operate, requiring only the turning of two 1/4-turn ball valves. The upgraded system has been successfully tested during two evacuation drills at an underground uranium mine. Using three injectors (one on the compressed air line and one on each of two intake air shafts), the system exhibited significant improvements in warning times over the mine's existing system. This report provides a detailed description of the system design and its demonstrated performance in two mine demonstrations.

Jan 1, 1981

By Jacob W. Young

A casual reading of the geological literature extant to-day would give one the impression that carbon is an element which by some chance or another always existed at or near the surface of the earth, and was never of a magmatic origin. The carbonaceous matter in shales is said to be of vegetal derivation; petroleum is stated to have been derived from vegetable matter or from marine animal bodies; if carbon or bituminous matter is found in igneous rocks or associated with metallic ores, the statement is made that deeply buried carbonaceous sedimentaries were undoubtedly the source from which such carbon or bituminous matter was derived. This, I do not consider a reasonable or common sense view of the matter. Carbon is one of the elements of which the earth is composed. In the table giving the periodicity of the elements it comes sixth in the order of increasing atomic weights. It is an element formed like all the rest were formed, and must be as common to the interior of the earth as the rest of the eighty-odd elements so far discovered. The spectroscopic analysis of light from the sun, and the stars, shows the presence of carbon in the sun and in the colder stars. Thus with carbon, an element, found throughout the universe as well as on the earth, it is entirely reasonable to consider it as present in the interior of the earth with the other elements. Such being the case, the magmatic origin for the various forms of carbon in rocks and ores is a rational and logical conclusion. If but a small fraction of thought and effort was made along these lines, which is made in fostering the idea of the organic origin of the carbon found in the earth's crust, untold advances in this phase of geological science would result.

Jan 1, 1925