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By W. P. Tassie

"The location of Quintette Coal Limited's pit and geologic nature of the dedicated reserves combine to introduce a number of factors which can adversely affect waste dump stability. These factors include steep terrain, variable material type and particle size, and precipitation. This paper describes the solutions to related waste dump problems. A brief geotechnical review of the waste dumps is given and Quintette's operational strategies during periods of dump stability and instability are discussed. Despite best efforts, failures occasionally occur and discussion is included on Quintette's success at bringing failed dumps safely back into use. IntroductionQuintette Coal Limited (QCL) property is situated on the east slope of the Rocky Mountains near Tumbler Ridge, approximately 120 km southwest of Dawson Creek, British Columbia. This surface mine is located on mountainous terrain and is subject to climatic extremes of wind, precipitation and temperature.QCL has a current annual production of 4.75 million tonnes of metallurgical coal with a stripping ratio of 7: 1. This correctly implies the extraction of over 33 million bank cubic metres (BCM) of waste which is placed on numerous waste dumps at various locations adjacent to the pit.There are three active pits - Mesa, Wolverine, and Shikano (Fig. 1). Shikano is a newly developed pit located near the plant site. It is not subject to the unique dump management problems prevalent at the Mesa and Wolverine pits, therefore the Shikano waste dumps will not be discussed . The dumps for the Mesa and Wolverine pits, however, have been technically and operationally challenging since shortly after mining began in 1983. Their characteristics, associated site specifics and management, therefore, are the subject of this paper.Waste dump locations for the Mesa and Wolverine pits are shown in Figures 2 and 3 as is the relative waste distribution . Each sub-pit is connected to a principal waste dump in reasonable proximity and to an alternate dump should disposal of waste be necessary at that location. The waste dumps are constructed from the top elevations initially to coincide with subpit development. In the initial years (1-7) waste dump heights will be up to 250 m, then, as the mine matures (8-20 years), waste dump maximum heights will continuously decrease to coincide with lower bench elevations"

Jan 1, 1988

By Pierre Boulanger

This paper describes a generic technology for modeling in real time the various operations of surface mines. Based on various sensor fusion techniques and high-speed network, a virtual reality model of a mine capable of representing not only static infrastructures but also mobile equipment such as trucks and excavators is created. The modeling technique deal with a wide range of sensors such as survey data, satellite pictures, ore concentration, machine condition indicators, video, sound, real-time GPS locator, range sensor, etc. The model created allows for every piece of information to be displayed in context allowing for a better temporal and spatial correlation of events by mine operators, planners, and supervisors. Syncrude, a Canadian mining company located in northern Alberta, is planning to use this technology, not only to understand oil sands mining processes better, but also to give decision-makers better access to the timely, accurate information from the field that they need to make informed decisions.

May 1, 2001

By Y. -B. Kang

New databases are being developed to provide the capability to evaluate the suitability of present and potential new Mg alloys for automotive applications through cost-effective calculations. An extensive and complete thermodynamic database is being prepared for Mg alloys formed from among 25 present and potential alloying elements. The database is being developed by critical evaluation, modeling and optimization of available phase equilibrium and thermodynamic data. It contains model parameters giving the thermodynamic properties as functions of temperature and composition. Using the FactSage thermodynamic software, users can access the database to calculate the amounts and compositions of all phases at equilibrium at any temperature and composition or to calculate any phase diagram section in multicomponent alloys, to follow the course of equilibrium or non-equilibrium cooling, to calculate corresponding heat effects, etc. A database of densities and lattice parameters of Mg alloys and intermetallics (as functions of temperature and composition) is also being developed in order to permit the calculation of volume changes during cooling and phase transformations, c/a ratios of the hcp phase, etc.

Jan 1, 2006

By D. Lindeman, R. M. Nendick

"From a technologist's point of view, there have been few fundamental 'breakthroughs' in the process of gold extraction since the turn of the century. However, the industry has made a great deal of progress in its response to the problems that have arisen: a changing demand for products, lower grade and more refractory ores, inflated labour and materials cost and the increasing control of governmental legislation. The trend in North America and South Africa to alleviate these problems has been to adopt a common policy to process larger tonnages of lowgrade ore through more efficient milling circuits. Here, however, is where the similarity ends.The purpose of this paper is to emphasise the different principles of practice employed by extraction plants in North America and South Africa to achieve the same common goal, namely gold bullion.2.0 INTRODUCTIONTwo very important aspects of extraction metallurgy for which the metallurgical engineer is responsible are plant design and plant commissioning.In North America and South Africa the importance of these aspects is due to the fact that both are related to the financial success of the project of which they form part. Good design is imperative if the capital invested in both the plant and the whole mining undertaking is to reap maximum profit. Furthermore, good design leads to a carefully planned and well executed start-up procedure resulting in bringing the plant into production on time, at designed efficiency and within budget.Due to the competent nature of the quartz pebble conglomerate and quartzite ore on the South African Witwatersrand, the characteristics of the ore type are not much different from one mine to the other. Thus a significant operating knowledge and experience has been built up over the years and there is considerably less risk in selecting a gold extraction process route."

Jan 1, 1992

Burr Mineral Resource has: ?Grade / Thickness / Tonnage ?Dry Caprock ?Low Carnallite ?Low Clay / Insolubles ?Flat & Continuous Deposit ?Proper depth

May 1, 2009

By Eric Konigsmann

"Omai Gold Mines is a large scale open pit gold mining operation located in central Guyana, South America with a 12,000 tonne per day milling facility. Mill operations were initiated in December 1992 with commercial production beginning in January 1993. The entire operation employs approximately 120 expatriates and some 800 Guyanese nationals and is expected to produce in excess of 250,000 ounces of gold per year. The total mineable reserves contain 2.5 million ounces of gold with a projected mine life of twelve years.The milling circuits feature an SABC grinding circuit, gravity concentration and a conventional CIP gold recovery circuit. This paper will review the mill start up and ""run-in"" phase during the first year of operation. Emphasis will be placed on descriptions of start up problems and circuit modifications, mill performance trends in 1993, and personnel training and development. An outlook for 1994 is also given.IntroductionOmai Gold Mines is a large scale, open pit gold mining operation located in the Potaro district of Guyana, South America, some 160 kilometers south of the capital city Georgetown. Although there are numerous small scale gold mining ventures in Guyana, particularly with the dredging operations on the rivers, Omai is the first hard rock, open pit mine to be developed in the country. At present, this mining operation is one of the largest gold mines in South America.The Omai gold deposit has been exploited for over one hundred years. In the late 1800's, a German syndicate used hydraulicing with subsequent gravimetric separators such as sluice boxes and trommel screens to recover gold from saprolite, a soft, oxidized, claylike mineral which covers much of the claim area. Through the early 1900's and up until the 1950's, numerous mining companies including Anaconda Mining Co. Ltd. explored and drilled the Omai deposit but the technology and low gold price of the day made the reserve uneconomic to develop."

Jan 1, 1994

By D. Harris, G. Ye, G. Oprea, J. Rigby, T. Troczynski

Sintering and ceramic bonding in refractory castables take place mainly in the binding system during the first heat-up and in service. Consequently the strength and the corrosion resistance of the hot face layer depend on the sintering ability of the complex mix of ceramic powders constituting the binding system. As a result, the use of nano- sized reactive powders in the binding system mixes would activate the sintering and enhance the ceramic matrix formation at temperatures below 1300°C. Our work presents the experimental data on sintering behavior of binding systems containing magnesium aluminate and alumina nano-powders in the temperature range of 800-1450°C. The results indicated that a ceramic matrix, similar to high temperature fired bricks, could be generated after firing at the relatively low temperatures available in the non-ferrous smelting furnaces.

Jan 1, 2004

By Jan Butra

In copper ore mines located in the Pre-Sudeten Monocline the deposit mining using room and pillar systems has been carried out for more than forty years. When implementing mining systems in deep copper ore mines it appeared to be necessary to adapt them to variable geological conditions and natural hazards. In the initial period of exploitation there were mainly caving and rockburst hazards. The adaptation of room and pillar system was connected with a state of knowledge in the scope of identifying, forecasting and controlling rock mass hazards. The new solutions allowed the safe and efficient exploitation of a blanket deposit of variable thickness from about 2 to 15m, seated on progressively increasing depth. They included exploitation in constrained conditions, such as in protective pillars. In the exploitation period, technical and organisational activities aimed at rockburst hazard control were introduced including active methods for controlling rockburst hazard and procedures for conducting mining works in the rockburst hazard conditions. When mining at a depth exceeding 1,200 m, the exploitation method and technique are additionally affected by thermal hazard and by gas and rock breakout hazard. New solutions of the room and pillar system and a longwall system with mechanical mining have been developed for exploitation in the associated hazard conditions. The require application of many innovative solutions in the scope of mining process and ore haulage mechanisation, excavation support and forecasting and control of existing hazards. The main purpose of these solutions is to conduct the safe and economically effective exploitation of the deposit.

Aug 1, 2013

By DAVID C. MILLER

Barite deposits occur worldwide and in a variety of geological environments. In recent years, several deposits of barite and barite-lead-zinc have been discovered in northern British Columbia, Yukon Territory and Alaska. Most are associated with Devonian-Mississippian age sediments, and many are syngenetic, bedded-type deposits. The Mel is a barite-lead-zinc deposit; it lies within Lower Cambrian strata and appears to be of epigenetic replacement origin. Figure I is an aerial view of the property from the south. Observations herein described are based largely upon field work, megascopic studies and two recent B.A.Sc. theses (Biasucci 1979, Rennie 1979).

Jan 1, 1984

By E. M. Shemang, C. E. Suh, L. Mbinkar, University of Yaounde

"Two iron deposits within the Precambrian mineral belt of Cameroon are described in detail for the first time: the Archean Metzimevin replacement iron deposit enclosed in Fe-enriched itabirite, and the Proterozoic granite-hosted, shear zone-related Mayo Binka magnetite deposit. In the Metzimevin de¬posit, quartz is corroded and microplaty hematite overprints martite-textured hematite. The Mayo Binka massive magnetite veins show evidence of deformation in magnetite (fracturing and microbrecciation) and in overgrowths of specular hematite (mechanical twinning and undulating extinction). The magnetite is partially replaced by hematite (martitization) and goethite. Ores from both deposits have >88% total Fe2O3 and low contents of contaminants such as SiO2, Al2O3, MgO, CaO, P2O5, and TiO2. They are also poor in Cu, Pb, Zn, V, Cr, and Ni. The Metzimevin massive hematite is characterized by an accentuated light rare earth element depletion relative to the Fe-enriched itabirite. It is suggested that the Metzimevin iron deposit is the result of hypogene leaching of gangue minerals from, and further hematitization of, an itabirite protore. Although the genesis of the Mayo Binka massive magnetite is unclear, it is spatially related to Neoproterozoic granitic rocks. The data allow some comparison of these little known, but pot¬entially economic iron deposits, with some of the world’s better investigated deposits, and are useful to the exploration efforts for iron ore currently underway in Cameroon and the Central African subregion.Deux gisements de fer de la ceinture minérale Précambrienne du Cameroun sont ici décrits en détail pour la première fois : le gisement de fer Archéen de Metzimevin formé par remplacement et encaissé par des itabirites enrichies en Fe, et le gisement de magnétite Protérozoïque de Mayo Binka as¬socié au cisaillement dans un granite. Au gisement de Metzimevin, le quartz est corrodé et de l’hématite en microplaquettes se développe au dépends de l’hématite a texture martitique. Les veines de magné¬tite massive de Mayo Binka présentent des évidences de déformation dans la magnétite (fracturation et microbréchification) et dans les surcroissances d’hématite spéculaire (Macles tectoniques et extinction ondulante). La magnétite est partiellement remplacée par l’hématite (martitisation) et par la goethite. Le minerai des deux gisements contient >88% de Fe2O3 total et un faible contenu en contaminants tels que SiO2, Al2O3, MgO, CaO, P2O5, et TiO2. Il est également pauvre en Cu, en Pb, en Zn, en V, en Cr et en Ni. L’hématite massive de Metzimevin est caractérisée par un appauvrissement relatif en terres rares légères relativement à l’itabirite enrichie en Fe. Il est suggéré que le gisement de fer de Metzimevin résulte du les¬sivage hypogène des minéraux de la gangue ainsi que de l’hématitisation poussée d’une préconcentration de fer dans l’itabirite. Bien que la genèse de la magnétite massive de Mayo Binka demeure obscure, elle est spatialement associée aux roches granitiques Néoprotérozoiques. Ces données permettent de comparer ces gisements de fer peu connus et potentiellement économiques avec certains des gisements mondiale¬ment mieux connus, aidant ainsi les efforts d’exploration présentement en cours en Afrique de l’ouest et au Cameroun."

Jan 1, 2008

By Y. Long

The deep-hole surface blasting technique is a prime method of iron ore mining. Blasting fragmentation is one of the important economic indicators that measures the blast method to obtain the iron ore. To improve the efficiency of the blasting method and further reduce the cost of the subsequent processing of iron ore, this paper summarizes measured data gained from a certain amount of blasting test conducted in an iron ore mine in Guangdong province, China. According to the data analysis, there are differences on iron ore blasting fragmentation by different indicators of deep-hole blasting, such as decoupling coefficient of charge, contact state between charge and borehole wall, and change of detonation position in charge. These factors were compared in terms of relevance and impact. Research shows: under certain rock conditions, the decoupling coefficient of the charge has a best range related to blasting fragmentation. Since the detonation position in charge determines the direction of propagation of the explosion stress wave through ore and rock, bottom initiation and mid initiation will help to improve the iron ore blasting fragmentation in joints fractured rock and ore. The research conclusions have important application value for program design of iron ore surface blasting and to guide other types of rock surface blasting.

Aug 1, 2013

By A. I. Gorshkov, Y. A. Bogdanov, O. Y. Bogdanova

Abstract - Detailed crystal-chemical study of iron and manganese oxides and some other minerals from low-temperature hydrothermal deposits in a newly discovered inactive mound in the TAG hydrothermal field were used to determine the precipitation sequence of mineral phases during lowtemperature processes and their post-sedimentary transformations. Particles of primary sedimentary X-ray amorphous proto-ferrihydrite with high silica content were replaced in situ by nontronite, ferrihydrite, or goethite during alteration. Ferrihydrite is the only proto-hematite phase. The transformation of the iron minerals, related to change in the physicochemical environment, is an important characteristic of low-temperature hydrothermal processes. The occurrence of hydrogenetic Fe vernadite and Mn feroxyhyte in the uppermost part of low-temperature deposits and bottom sediments near the base of the mound is evidence for cessation of low-temperature hydrothermal processes. Among the investigated mineral phases, goethite, nontronite, and hematite are stable in reduced sediments only.

Jan 1, 1999

By A. Iizuka

This study was aimed at separating and recovering arsenic, antimony, and tin from refining byproducts generated in a nonferrous smelter. The target byproduct was a silicate slag containing the above elements. The silicate structure of the slag was destroyed by alkali roasting, which then enabled leaching of arsenic, antimony and tin in solution effectively. Arsenic was selectively leached out by hot water after alkali roasting of the slag, while remained antimony and tin in the residue were leached out by a hot hydrochloric acid solution. However, when the solid-liquid ratio in the leaching solution was increased, hydrous gelatinous silica (gel-like silica) was formed during the hydrochloric acid treatment and filtration became difficult. Therefore, high temperature and high pressure leaching was attempted to improve the filterability of the silica leaching residue. In the high temperature and high pressure treatment, the hydrous gel-like silica was transformed into easily filterable aggregated silica, and thus, filtration became easy. By investigating the neutralization and sulfurization treatment for the obtained hydrochloric acid leachate (second leachate), it was possible to separate antimony and tin. INTRODUCTION This study aims to separate arsenic and recover valuable metals such as antimony and tin from refining byproducts generated in a nonferrous smelter. The target smelting byproduct is antimony-containing slag in this study. In many cases, alkali roasting was adopted as pretreatment for extraction and recovering valuable metals from smelting residues and wastes (Rao, 2006). For antimony-containing slag in this study, one effective method for separating arsenic is to convert arsenic to sodium arsenate (Na3AsO4) by roasting with a sodium compound and then to remove arsenic by hot water leaching. In addition, by alkali roasting, the silicate structure of the slag is destroyed, and effectively alkalizing tin and antimony is accomplished. Then, precipitating and recovering tin and antimony leached into the acid solution are considered possible by sulfurization and neutralization treatments. In this research, we conducted basic studies on the following. 1) Destruction of silicate structure in slag by alkali roasting and leachability of arsenic. 2) Conversion of hydrous gelatinous silica to aggregated silica by hydrochloric acid treatment of residues after arsenic leaching under high temperature and high pressure, as well as leachability of antimony and tin. 3) Separation and recovery of antimony and tin by sulfurization and neutralization treatments of hydrochloric acid leachate. These topics of investigation can support to consider the separation and recovery process of arsenic, antimony, and tin from antimony containing slag.

Jan 1, 2019

By J. C. Mitcheson

Mr. President, Mr. Mayor, Ladies & Gentlemen: IT GIVES ME great pleasure to have the opportunity, today, to speak on behalf of all the constituent. bodies of the Common-wealth Council of Mining and Metallurgical Institutions. For the past month we delegates have been right royally entertained across the length and breadth of Canada by Provincial Governments, City Councils, and other equally generous public organizations and private corporations. On this occasion, however, the President of The Canadian Institute of Mining and Metallurgy, our good friend Dr. H. J. Fraser, has been our host at the enjoyable reception preceding this Institute Luncheon, which luncheon was sponsored by our official host, The Canadian Institute of Mining and Metallurgy, one of our .constituent bodies.

Jan 1, 1957

By Dwayne D. Tannant

The Fox Pit at EKATI Diamond Mine reached a depth of approximately 150 m as of September 2005. The pit is designed with 11 m wide benches excavated using a double benching technique leaving 30 m high bench faces. A series of blasting tests were conducted to improve catch bench reliability and increase the percentage of benches that meet an 11 m catch width. The design changes focussed on reducing damage to the bench crest because maintaining the bench crests is the most important factor in achieving good bench reliability. The most significant improvement was obtained by raising the bottoms of the lower trim blastholes by 0.5 m. This change decreases the depth of broken rock below the final bench elevation, and consequently reduces damage to rock that forms the bench crest below. Another improvement was the use of smaller diameter (165 mm vs. 270 mm) blastholes in the A and B rows for the upper trim blast. This change reduces the charge per delay during detonation, reduces the powder factor slightly, and reduces the energy affecting the final pit wall and crest. As mining and the blast testing progressed, the portion of the bench with crest achievements (>11 m) increased from 57% to 75%.

May 1, 2006

Ion Exchange is finding a greater role in copper processing, and hydrometallurgy in general, both as a technique for removing impurities and as a means of adding value through the recovery of secondary metals. Both the gold and uranium industries use resin adsorption as a primary production technique. While hydrometallurgical processes predominantly rely on solvent extraction as the mainstay of copper recovery there are a number of projects, in particular polymetallic deposits, which are considering the use of resin recovery as an alternative or supplemental production technique. A number of applications have been developed and proven at commercial scale for the removal/control of impurities (iron, antimony and bismuth) from copper electrolytes. These are well documented ion exchange applications. Increasing metal values and scarcity of certain metals are focusing companies to look at secondary metals recovery rather than losing these often highly valuable metals to tails residues. Bleed streams are being seen as valuable opportunities to recover contained metals; iron, copper, nickel, cobalt, bismuth, antimony and rhenium are all metals being targeted for removal or recovery from process solutions, electrolytes and bleed streams. An overview of currently applied techniques as well as some developmental technologies for impurity removal and secondary metals recovery is presented to provide insight into the advantages and flexibility of ion exchange applications in metals processing.

Jan 1, 2007

By B. S. W. Buffam

"The property of Moneta Porcupine Mines, Limited, consists of a group of eight claims in Tisdale township, Ontario. It includes part of the townsite of the town of Timmins, and adjoins the west boundaries of the Hollin_ger Consolidated and Mace properties. The Moneta property was first staked in 1909, about a year after the first discovery of gold in the Porcupine camp. In 1910 the Moneta Company was incorporated and some preliminary exploratory work performed by Nova Scotia Mines of Cobalt. In 1912 English interests advanced $90,000 for diamond drilling and underground work. One drill hole gave high assays, but apparently the records were poorly kept or the cores were interchanged. As a consequence, when underground exploration was undertaken in 1923 it was directed south rather than west and no ore was found . In 1924 about 5,000 feet of diamond drilling was done in the southern part of the property, but without intersecting ore.In 1931 W. E. Segsworth assumed the direction of the property. Diamond drilling commenced on August 18, 1936. The first hole intersected 9.9 feet of ore averaging 1.23 oz. gold a ton. Underground work was started early in 1937. A mill was erected in the autumn and the first gold brick was poured January 29, 1938.The Moneta mill began operation on January 2, 1938, and the following table gives a summary of the production to June 30, 1943, when the mill was closed."

Jan 1, 1954

By G. H. Babcock, D. A. Knight, V. G. Medina

"Production commenced at the Golden Sunlight Mine in 1983 and at Kidston Gold Mine in 1985. These projects were both constructed under the management of the Placer Dome Inc. (Technical Services) group of Vancouver, B.C.Golden Sunlight uses a conventional rod mill/ball mill grinding circuit while Kidston uses a SAG /ball mill, and later on, SABC circuit. Since the hardness of the ore and the fineness of the primary grind in both mines are about the same, a meaningful cost comparison can be made. The comparison is made on the basis of capital and operating costs.The result of this study indicates that a significant capital cost savings can be achieved in favour of the SAG /ball mill circuit when the ore is amenable to semi-autogenous grinding. With a good maintenance program, the operating cost for the SAG /ball mill circuit could also be lower that the conventional rod mill/ball mill circuit.HISTORYGolden Sunlight MineGolden Sunlight is a 5 530 t/d gold mine located near Whitehall, a small town 60 km east of Butte, Montana. Originally optioned by PDI U.S. in 1958, the development of the property waited until 1981 when economic conditions became favorable for the project to proceed.Semiautogenous grinding tests were conducted during the final stages of the feasibility study. The hard near surface ore was not quite amenable to semi-autogenous grinding. The best result produced from a series of tests using a 1.83 m diameter mill was a semiautogenous work index of 39. This is substantially higher than the 22 Bond work index of the sample used in the testwork. A conventional SAG/ball mill circuit for this ore will be extremely inefficient, and for this reason, this circuit was rejected in favour of a conventional rod mill/ball mill circuit."

Jan 1, 1991

By A. Himsley

"There is an ever-increasing demand these days for efficient methods of removing metals from solutions especially for selectively recovering a particular metal from a mixture of metals in solution.Up until the mid l 930's the only methods widely practiced for such separations involved precipitation techniques or electrolysis. Both these methods have limitations and indeed can only be used for certain metals.It is only within the last 40 years or so when synthetic ion exchange materials became available that chemists in industry and universities have been able to apply ion exchange techniques to a wide variety of separations that not only would be impossible by precipitation methods but which are now achieved with much greater efficiency.Ion Exchange TechniquesIon exchange is a unit process that can be applied using either liquid ion exchangers or solid resin particles. Liquid ion exchange - or solvent extraction as it is often referred to - is used in a number of special areas dictated mainly by the nature of the separation.On the other hand, ion exchange resins are much more widely used and consequently a great deal more is known about their application to a variety of metal separations.In both systems there is a loss of the ion exchange material which in the case of solvent extraction results in hydrocarbons going to waste. The ion exchange resin systems lose resin in the form of small particles, referred to as ""resin fines"", and these are insoluble.The loss of liquid ion exchanger is due to the fact that it is slightly soluble in water and consequently the loss is a function of the volume of liquid with which it comes into contact and is not related to the amount of metal processed."

Jan 1, 1975

By W. W. Weber

"The Mine property comprises some 700 acres in ranges VI and VII, Barraute township, about thirty-seven miles due north of Val d'Or in northwestern Quebec.The transformation of a small farming community into the youngest and largest zinc producer in eastern Canada began late in the autumn of 1950. At this time, a geological survey party of the Quebec Department of Mines discovered sphalerite-pyrite mineralization in a strong regional shear structure crossing range VII of Barraute township. Diamond drilling commenced in November 1950, and by June 1951 a total of more than 63,000 feet of drilling, at fifty-foot intervals, had explored an ore zone 2,500 feet in length and 102 feet in average width to a depth of 700 feet, the deepest ore intersection.Production started late in 1952, and is at present in excess of 4,000 tons per day. Production in 1954 of77,790, 166 lbs. of zinc and 989,610 oz. of silver, from 1,525,284 tons of ore, makes this mine the largest zinc producer in eastern Canada.General GeologyAll the consolidated rocks of the area are Precambrian, and most of them are volcanic. They consist mainly of subsiliceous Javas, with smaller amounts of siliceous to intermediate lavas and pyroclastic rocks. The lavas have been intruded contemporaneously by many sill-like bodies of coarser-grained diorite and gabbro. There are no sedimentary rocks within ten miles of the mine.A period of major folding and faulting was followed by intrusion of granite. The volcanic rocks have been compressed into isoclinal folds trending roughly east-west, and the granitic batholiths also show a rude lineal alignment in the same direction. The granitic masses vary consider-ably in composition, ranging from the potassic LaCorne granite, ten miles south of the mine, to the sodic Duverny mass, ten miles west. In addition there is a variation from a general granitic core to dioritic and gabbroic phases on the margins and in satellitic intrusions."

Jan 1, 1949