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By R. W. Raymond

(Chattanooga Meeting, October, 1908.) THE immense commercial value of the Gayley dry-blast process has been established beyond controversy. The testimony of practical blast-furnace managers, on both sides of the Atlantic, agrees that it reduces the cost of pig-iron about $1 per ton; but from the same testimony it appears that this direct economy does not by any means cover its commercial advantages-in fact, that under conditions frequently encountered in practice, it presents other benefits of even greater immediate financial importance. To this point I shall recur in a later part of the present paper. The history of the reception given to this invention, especially on the other side of the Atlantic, has repeated an experience familiar to American engineers. First, the reports of our practice were rejected as theoretically impossible, according to generally accepted notions and formulas; then the figures were reluctantly accepted ; and finally the attempt has been made to explain how they could have been obtained. As to the Gayley dry blast, we Americans have been for several years in the last stage of the discussion, and the rest of the professional world is rapidly coming to it. Meanwhile, the remark has been repeatedly made that, whatever Mr. Gayley's process may turn out to be worth, it was not an invention on his part, but simply the energetic and persevering execution of a procedure already proposed by others. This question I wish to discuss first in the present paper. I. WHAT DID MR. GAYLEY INVENT Realizing that this is not the place for detailed argument on an issue of patent law, I shall not undertake to quote and criticise the publications prior to Mr. Gayley's first patents. It may be admitted, without such critical analysis, that the possi-

Jan 1, 1909

By W. Bassow

In June 1972, when the United Nations convened its historic Conference on the Human Environment, only 24 countries had established government agencies with environmental responsibilities. Of these, 11 were in the industrialized world, 13 in the Third World. By 1985, the number had dramatically surged to a world-wide total of 145, with the greatest growth among the developing countries to 110, an increase of almost 1000%.

Jan 1, 1988

By Peter Grawenhof

In steel mills universal joint shafts, slipper spindles and gear spindles are used to overcome the design- and process- related offset between the axis of the motors and the work rolls. At the roll side the available space for the couplings is limited by the minimum work roll diameter. This leads to extremely high loaded components of the universal couplings especially at the roll side joints. Furthermore modern steel mills continuously strive to roll larger plates and materials with increased strength. This requires drive solutions with even higher torque capacity. For these applications conventional design joints are not sufficient anymore. Even alternative solutions such as hybrid- or offset- designs fall short. Therefore the companies Voith and BUMA Engineering developed together the new GearLink drive concept in close cooperation with the Voestalpine Grobblech GmbH. A completely new combination of universal joints and gear couplings offers an up to now unique solution enabling the use of 1,35- times bigger joint with a 2,5- times higher torque capacity and a 20- times longer lifetime. The GearLink system was first time successfully taken into operation at Voestalpine Grobblech in December 2013 and is up to now working without issue.

Aug 16, 2017

By D. S. Preece, S. Silling, A. Bhuiyan, C. M. Lownds

GEM (Geologic Element Motion) is a Discrete Element Method (DEM) capability for blast-induced heave simulation with a very fast computational algorithm that can efficiently treat many different element shapes by utilizing alternating arcs and lines. GEM calculates rock motion from a knowledge of the gas pressure moving the elements. This requires an expression for the pressure vs volume, or the adiabat, of the explosion product gases. This work uses an analytical expression for the adiabat derived from the explosive’s properties. The effect of the explosive detonation pressure in crushing an annulus of rock, and setting up a shock wave, is termed Brisance. GEM incorporates a working hypothesis for the deleterious effect of Brisance on subsequent rock motion.

Jan 1, 2024

By J. Garretson

When mining accidents occur, workers often become trapped and/or incapacitated. Current rescue operations can be dangerous and too slow to produce favorable outcomes. Currently, no method exists for rescue crews to scout ahead at critical times to assess the situation. Sandia National Laboratories (SNL), through a National Institute for Occupational Safety and Health (NIOSH) sponsored program has developed the Gemini-Scout mine rescue platform. The Gemini-Scout was created to assist in underground mine rescue missions. It has been designed to go into potentially hazardous environments to assess the conditions (structural, air quality, temperature). In addition, it will enable two-way communications with potential survivors prior to human rescue teams being able to enter the area. The Gemini platform is a dual tracked-chassis design, which gives the robot excellent mobility in unstructured environments. The design includes a passive 2-degree of freedom joint between two identical bodies allowing for ±30deg of pitch and roll. In addition to the base mobility platform, the Gemini-Scout incorporates many other features to help it succeed in its underground mission. The electronics are mounted in explosion proof housings to ensure safe operations in hazardous gas environments. The platform is also able to operate in up to 18in of standing water with its elevated pan/tilt cameras for navigation. A four-channel video link and Two-way audio on the vehicle help to ensure located survivors can communicate with the robot operators. The platform also incorporates a Mine Safety and Health Administration (MSHA) approved multi-gas sensor to monitor air quality. SNL believes that this technology is broad enough to be appealing to other first responders, such as police, firefighters and medical personnel. Gemini could easily be fitted to handle earthquake and fire scenarios, and it could provide relief in currently inaccessible situations.

Jan 1, 2012

By J. Weyer

"Colored gemstones are most often mined in small scale artisanal mining operations. Sri Lanka is well known as source for precious stones since thousands of years. Gemstones are mine in small open pits, directly in rivers (river dredging) and in underground mines. Almost all mined deposits are alluvial deposits. PRECIOUS STONES AND DEPOSITS Precious stones from Sri Lanka are well known for thousands of years. Tales and legends from Arabia, India, China and reports from discoverers like Marco Polo describe the fabulous stones from Ceylon which was the name for Sri Lanka before 1972. Already 1000 BC King Salomon got valuable gemstones from the legendary Queen of Sheba on her visit to Jerusalem. Paintings (frescoes) of the “cloud maidens” with huge gemstones can be seen at the “mirror walls” of the Sigiriya rock fortress - one of the eight World Heritages Sites of Sri Lanka.And even today some of the most valuable and most desired gemstones come from Sri Lanka. The term “Ceylon Sapphire” stands for an excellent royal blue color of high quality corundum from Sri Lanka. Reason enough to look a bit closer how these gemstones are mined. Sri Lanka has rich gemstone deposits which are mined underground, in small open pits or directly within a river. Some of the primary deposits in magmatic and metamorphic rock are also known, but most gemstones are mined in secondary alluvial deposits. Gem bearing deposits can be found in a band from NW to SE. Highly probable deposits and main mining areas can be found around Ratnapura – the city of gems, down to the coast (Matale) and up to the region around Elahera. These secondary deposits are mostly thin layers of gravel and sand, so called “illam”. The depth can vary between some dm to 10 25 m or even almost 40 m. But the average depth is about 12 m. Gemstone mining is controlled, licensed and regulated by a special authority – the National Gem and Jewelry Authority - which was founded in 1993. Another task of this authority is the promotion and development of the gemstone industry and the control of import and export of gemstones. Any violence of the NGJA law can lead to a fine or even up to 5 years imprisonment. To increase the confidence in the gemstone industry the Authority offers a unique service to foreigners. All bought gemstones can be tested free of charge in certain laboratories in Ratnapura and Colombo. So visitors can be sure they got no imitations, wrong stones or even synthetic stones or glass. It was said that detected synthetic stones will be destroyed and the seller will do all he can to replace the stone with the right stone. Otherwise he will lose his license."

Jan 1, 2016

By George Frederick Kunz

Mexico has been famous for its silver-mines ever since the Spanish conquest; but in respect to gems, although many varieties occur, yet only a few have been obtained in any important amount. Considering the extent of country in Mexico and ill the adjoining States of the Central American Republics, and the richness of mineral wealth that must surely exist there, our present knowledge of the occurrence of precious stones is remarkably small. The great prevalence of igneous rocks would lead us to anticipate the future discovery of many localities of gems and ornamental stones, when fuller scientific exploration shall have taken place.* At the present time the only gem-stone that is systematically mined in Mexico is opal, and the only important ornamental stone is tecali, the so-called Mexican onyx. In addition to these may be mentioned the pink garnet, or rosolite, found in one

Jan 1, 1902

By S R. Pecover

AustraliaÆs opal and sapphire mining industry has fallen from its peak in the 1980s and 1990s into a significant low today. This is not due to exhaustion of the resource, but instead an over-reliance of the Australian miner on achieving a fair price for the gemstone product from offshore middlemen dealers. Gemstone and geological research is also at a low as Federal higher education expenditure has fallen with research institutions relying increasingly on private funding in an environment of restricted autonomy and flexibility for researchers. What little remaining research skills the universities have is being bled into the private sector as a result of the mining boom and encouraged by lower than average academic salaries. Nevertheless, some highly innovative research has been taking place, often by self-funded individuals and retired academics simply with a desire to advance the understanding of the particular branch of science in which they are interested. New models for the formation of sapphire and opal are now beginning to be applied to the exploration for these gemstone commodities. This research, together with well thought out plans for managing the gemstone product through its value-adding steps to the jewellery retail level, has the potential to bring about a resurgence in the Australian gemstone industry.

Jan 1, 2008

By F. C. Kelley, L. L. Wyman

In order to clarify and amplify the existing data concerning the action of the cementing material in cemented tungsten carbide alloys, the authors have initiated this investigation of the entire range of cobalt-tungsten carbide alloys. Inasmuch as the ultimate objective is relative to what actually goes on during the sintering of cemented tungsten carbide materials, this work was necessarily restricted to heat treatments similar to those used in actual production of these materials. In the course of numerous experiments, the authors have noted several conditions that indicated that there was a solubility to be considered. Among these factors are the following: 1. Many of the alloys showed a much larger amount of binding constituent to be present than could possibly be accounted for by the cobalt content. 2. In many areas, grains of the carbide constituent are much larger than the particles of carbide originally added. In addition, these grains are of very regular contour. 2a. In samples of cemented tungsten carbide which had been fused in the atomic hydrogen torch in the presence of excess binder constituent, immense grains are formed, and their shapes are very regular. This is also true when the cemented tungsten carbide of 13 per cent. Co content is fused alone in the atomic hydrogen torch. Contrary to general expectation, chemical analysis of this material, after fusion in the atomic hydrogen torch, checks the analysis of unfused material. 3. In making the cemented tungsten carbide materials by the process of exerting the pressure at the time of heating a certain portion of the ' contents squeezed out of the mold. Chemical analysis has shown that this material contains approximately 12 to 20 per cent. of tungsten. The microstructure shows a cored dendritic structure interlaced with eutectic network, and some graphite, as shown in Fig. 1. 4. Thermal analysis of these materials has consistently indicated an arrest point close to 1350" C.

Jan 1, 1931

By John R. Freeman

The die pressing of brass may be described as a method of producing irregularly shaped parts of brass and other copper alloys by hot deformation in a die under pressure. Die pressing of brass was first developed as an improvement on sand castings in order to obtain irregularly shaped articles of brass with superior surfaces, a closer tolerance in dimensions, a denser structure, freedom from porosity and elimination of the relatively large amount of scrap invariably attached to sand castings. The freedom from sandy surfaces with consequent greater tool life in machining operations was also recognized as well as elimination of losses due to the uncovering of blowholes in machining operations. Die pressing also gave alloys of superior strength. Die pressings today are made from extruded rod or shapes, according to design of the part to be made. The greater number of pressings are made from round rod, because of its relatively lower cost and ease of handling. The rod is first sheared or sawed into desired lengths, the diameter of rod used and length of "slug" or "rivet" depending upon ultimate weight and shape of the die-pressed part to be made and design of die. The dimensions of the slug are figured so as to give the minimum amount of scrap to be sheared from the pressing as it comes from the die. Extruded shapes having I, T or X sections are often used when the finished part is to have a similar shape or heavy sections are joined by relatively light sections of considerable length. A rod bent in the shape of a U is also used on occasion, for similar reasons. Proper shearing of the slugs is of considerable importance. The sheared ends of the slugs should be as flat and straight as possible. Improperly sheared ends having an angle to the axis of the bar or a rough, uneven surface are liable to give folds or laps in the finished pressing and proportionately high rejections. The property of shearing varies considerably with different alloys and should be considered in the selection of a material for a given part. Where satisfactory shearing is not possible, the slugs may be cut from the bar by power saws. Extruded

Jan 1, 1931

By Frank T. Sisco, Selma F. Hermann

gancse constituent in the alpha grains. Nickel produces a structure of alpha plus cutectoid almost identical with that of the normal aluminum bronze (Fig. 38), except for the rod-shaped nickel constituent in the alpha grains. Silicon produccs a light structure with small regular needles, possibly a modified form of beta. Fig. 45 shows the alpha plus beta structure of the normal 10 per cent. aluminum alloy as quenched. Manganese produces large grains of beta with alpha as a tiny constituent scattered throughout the spceimen. Silicon, on the other hand, produces all alpha, with free silicon present. One per cent. iron produces alpha plus beta, with a tiny constituent present in the alpha grains. Five per cent. iron introduces twins in the alpha and a nodular iron constituent in both the alpha and the beta. Figs. 50-58 include the structures of the alloys with 8 per cent, aluminum, tempered at 400" C. and at 650" C. Fig. 50 is the normal structure as drawn at 400" C!. It consists of large grains of twinned alpha plus a very small amount of beta. One per cent. silicon increases the amount of beta enormously, but when tempered at 650' C, the beta degenerates to a hard blue network constituent. One per cent. cobalt results in a structure of exceedingly fine-grained, twinned alpha, heavily mottled. Nickel produces large soft grains of alpha with a dot constituent in some of the grains, when tempered at 650" C. Manganese, when tempered at 400" C. produces alpha grains and shows the decom-

Jan 1, 1931

By Alan Morris

The investigation of the hot-working properties of metals and alloys furnishes a problem which has been attacked in many ways. Tensile, impact and hardness tests on heated specimens have furnished interesting data, but in most cases either the tests are difficult to make or the results hard to translate into terms of practical value. Some investigators have used the drop hammer to advantage. It furnishes a rapid and simple method of comparing the plasticity of metals at elevated temperatures. The indications obtained by its use are of value only in so far as their significance is understood and they can be intelligently used to predict the behavior of a given metal under given hot-working conditions. The work reported here was undertaken not only to add something to the existing volume of such data but also to contribute to our understanding of the results. Doerinckel and Trockels1 used cylindrical specimens and determined the work required to reduce the specimen to one-half the original height. Ellis2 studied the effect of constitution on the malleability of steel at high temperature. His method and that of Kent3 were similar to the one used in the present work. The tests described by Kent were made on samples of tin, zinc, aluminum, copper, lead, 70:30 and 60:40 brasses, with and without a small quantity of lead. He concluded that the test would "indicate whether a material can be forged at a given temperature without cracking." This interpretation must be used with caution. While it is probably true within limits, one must consider the severity of the forging operation. Again, it will not apply strictly to forms of hot working other than forging. For instance, an alloy running 61.0 per cent. copper, 3.25 per cent. lead, remainder zinc, will crack badly in the test, yet, it is extruded commercially. When the possibility of hot-working a new alloy is being considered a study of its drop-hammer test should help

Jan 1, 1931

By Zárate G. E.

Practical and statistical considerations concerned with the sampling, sample preparation and chemical analysis of precious metal ores are reviewed. The principal requirements related with the characteristics of sample cutter, sample preparation, equipment and methods are discussed. The main errors introduced in the different stages of the sampling systems are defined. The application of statistical techniques to evaluate these errors to determine the ore grade variation and to design the number of increments needed to get an accurate assay are presented. Finally, results obtained with the application of this method to gold and silver ores are analyzed and some recommendations are given.

Jan 1, 1984

By Wilbur Jurden

THE writer's first experience with a nonferrous reduction plant of great magnitude was at the Washoe reduction works of Anaconda some 35 years ago. Here was a plant which had been planned with remarkable skill and foresight considering the time and the state of development of copper-plant practice in the year 1902. The designer utilized topography to fullest extent to provide proper sequence of operations and, what is most remarkable, to leave adequate space for future developments, most of which at that time were unknown. However, the practice then was to locate the various units of the reduction works at the most advantageous points of the existing terrain with little regard for tramming or other auxiliaries and then connect these various units by the essential trackage, conveyor systems, piping, etc., as the need developed. This occasionally led to undesirable track arrangements, sharp curves, and steep grades, especially when it became necessary to extend various portions of the plant. Conveyor systems also became rather complicated, running as they did at various angles, and such items as piping and electrical distribution were often found to be in the wrong place, entirely inadequate in size, or awkwardly arranged for any kind of extension. This condition was not peculiar to Anaconda, for all copper plants at that time were built in the same manner and it was the constant association with these difficulties which, in the year 1925, influenced the layout of the Andes Copper Mining Co. plant. In that plant all trackage was laid out straight and level, all conveyors at right angles to each other with minimum length and number of transfers. All buildings were placed parallel and the main structures were complete for all purposes so that auxiliary buildings and dog houses would not be added later. Piping and electrical work was provided for in the original layout and carefully designed to avoid additions and alterations, and careful study given to every movement of material throughout the entire plant so that it would be accomplished with the least possible effort. Naturally it was hardly expected to attain all these objectives perfectly but our efforts did succeed in creating a plant which was unique and outstanding for its time-1927. It was also most gratifying to find that these design principles contributed to considerable savings starting right in the drafting room, carrying through the construction and ultimately yielding savings in operations and manpower. Not only that, but such a plant gives the observer an impression of symmetry and order, is more attractive to the workmen, and unquestionably eliminates many accident hazards. However, the Andes plant buildings were fitted to the existing terrain instead of having terrain created to fit the buildings-an item which we found advantageous to correct on the next large plant. At Morenci in 1939, all of the desirable features of the Andes plant such as parallel buildings, etc., were incorporated; but we went one step further-power shovels were brought in to make the terrain fit the reduction works. The result at Morenci is well-known and needs no elaboration here, but the success achieved by the design methods used for this and previous plants naturally influenced and guided the layout of the Chuquicamata sulphide plant which is the largest yet conceived. Chuquicamata Plant Design At Chuquicamata several factors not encountered previously complicated the problem to a great extent. The most desirable location for the smelter would allow smelter gases to blow directly into the open-pit mine already producing 60,000 tons of oxide ore per day and employing 1550 men. This, of course, would be a serious condition and, therefore, we were forced to move the smelter to a less desirable location but followed our previous experience at Morenci and made the terrain fit the job. The most difficult problem, however, was the provision for receiving various types of ore both by rail and conveyor. These consisted of: 1-Sulphide-bearing residue from the stockpile from which oxide copper had previously been leached. 2-Sulphide-bearing residue coming direct from the leaching vats. 3-Sulphide ore crushed at the existing crushing plants and hauled to the concentrator in cars. 4-Sulphide ore from the new crushing plant adjacent to the concentrator. 5-Sulphide ore obtained

Jan 1, 1952

"Chairman - To start this discussion off, I wonder if Mr. Dave Livingstone or Mr. Jeffrey of Granisle Copper would give a description of the crushing plant at Granisle since it is somewhat different from the usual plant, W. N. Jeffrey - Granisle Copper The main difference between the Granisle crushing plant and many others is the Livingstone method of putting the screens under the crushers instead of above them. This method allows a more compact arrangement and eliminates the heavy superstructure required to take care of the screen vibration when the screens are mounted above the crushers. There is a small surge bin above the tertiary crusher which takes care of the variation in circulating loads.All three crushers are gyratory crushers. There is no grizzly ahead of the primary crusher but the fines are removed from the primary crusher discharge at the first screen and sent directly to the fine ore bins. E, Thornton - Sullivan GroupDo you have any coarse ore storage outside?w. N. Jeffrey - Yes, there is about 6000 tons live storage, We have very little trouble with freezing even though it is open storage.E. Thornton - Sullivan GroupDoes rain cause any problem?w. N. Jeffrey - It sometime creates a problem because the storage area is on a slope. It is mainly a problem of keeping the drainage ditches open.Question – What is the size of the primary gyratory crusher and how does it work on run of mine size materials, in other words, do you have a problem with oversize material and how do you handle the oversize rock?w. N. Jeffrey - The primary gyratory is a 42 x 65 with a nominal open side setting of 61'. We do at times get a run of oversize material. For anything too large for the crusher to handle, we use what is known as the Esco hook, which is a type of grapple used to remove oversize rocks.The disadvantage with this equipment is that the crane is too slow. I am sure there must be better arrangements than the one we have,"

Jan 1, 1971

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

5. General Escapeway Requirements 5.1 Escape Routes Present escapeway regulations state "Every mine shall have two separate properly maintained escapeways to the surface which are so positioned that damage to one shall not lessen the effectiveness of the other, or a method of refuge shall be provided when only one opening to the surface is possible." "Escape routes shall be a. Inspected at regular intervals and maintained in safe, travellable condition, b. Marked with conspicuous and easily read direction signs that clearly indicate the ways of escape." "Application. "Regular" intervals means at intervals no greater than monthly where conditions are stable and oftener where conditions may change." "Designated escapeways inclined more than 30* from the horizontal shall be equipped with stairways, ladders, cleated walkways, or emergency hoisting facilities." As can be noted in present and proposed regulations there must be two separate properly maintained escapeways. In most operations, the escapeways will consist of one route that is the normal travelway used in day to day operations. The second route is usually a return airway through old work areas. Based on this generally accepted practice, we will designate the two types as primary and secondary.

Jan 1, 1976

By R. L. Stanton

"The present contribution is complementary with a preceding one on the field association of the conform-able ""pyritic"" deposits. It considers the more important features of their mineralogical constitution and their microtextures, re-examines the present interpretations of these, and of-fer-some alternative explanations. The term ""pyritic"" for these de-posits is m many cases a misnomer, as two quite distinct ore types are inuolve. One is a banded pyritic sphalerite-galena-chalcopyrite ore (for which the term '•pyritic"" is in-deed quite suitable), while the other is non-banded and is composed essentially of pyrrhotite and chalcopyrite. In addition to these constitutional differences, each is distinctive in general appearance and texture. The occurrence of two such consistent but clearly distinguishable ore types is attributed -rather than to difference in source material and pressure-temperature conditions of deposition -to the contribution of similar source material to dissimilarly oxygenated environments of sedimentation. Textures in the banded ores generally thought to be indicative of replacement or of high-temperature exsolution are explained by slow, law-temperature segregation in situ during compaction, folding, and regional metamorphism."

Jan 1, 1960

By J. F. Wright

Introduction Previous to 1924 the mining fields of Manitoba and adjoining territory had not been prospected in detail, and the reports of the exploration of the mineral discoveries to that date had been discouraging. As a result of the apparent failure of all the mining operations, some considered that geological conditions in the country westward from lake Superior extending across western Ontario, eastern and northern Manitoba, and northern Saskatchewan, were different from those in the northeastern part of Ontario, where large gold mines had been developed. Discoveries of importance thus were necessary to renew interest in the mining possibilities of this part of the Canadian Shield, and the successful operations at Flin Flon and Howey in large part were responsible for the beginning of the present activity in what may be described as the part of the pre-Cambrian Shield within central Canada. In Manitoba, the more important developments at present are in the Central Manitoba, Gods Lake, and Knee Lake fields. The large area from west of Flin Flon east to Herb Lake, also, is being explored carefully for gold deposits of merit. A number of properties in Red Lake, Woman Lake, and Pickle Crow areas are being drilled and explored underground. Many of the mines of the Lake of the Woods area, that were producing gold 30 years ago, are re-opened, and new prospects in this field and in the country to the east are being explored. The recent development of Little Long Lac mine in an area near the railway, and considered by some to have been thoroughly prospected years ago, has stimulated interest in the areas formerly prospected. In the autumn of 1934, the belts of greenstone and sediments in the country east of lake Nipigon were staked, and deposits in these fields will be explored in detail this year. This paper is presented to discuss the general features of the geology and gold deposits of the various prospecting fields in Manitoba and adjoining territory. Details of a number of the areas and mines will be presented at this meeting in papers by Barton on Little Long Lac, Tanton on Sturgeon River, Baker on Gods Lake, and Brownell and Kinkel on Flin Flon. Although mining was not active in most of this territory previous to 1930, geologists of the various government departments continued field studies and interesting reports were issued.

Jan 1, 1935

By L. S. Beck

"IntroductionThe Beaverlodge District is an important mineralogenic province of pitchblende and occupies about 1300 square kilometres centred on Beaverlodge Lake near the north shore of Lake Athabasca in northwest Saskatchewan (Fig. 1). Uranium City is the main settlement of the area and is serviced by scheduled aircraft from Edmonton, some 700 km to the southwest, and from Prince Albert which lies a similar distance to the south.During the summer, boats and barges supply the area from the railhead to Fort McMurray via the Athabasca River and Lake Athabasca, a distance of about 550 km. For the past few years a winter road has been maintained across Lake Athabasca to Cluff Lake to connect with Highway 155.The topography of the area is typical of the Precambrian Shield with generally low relief and a disorganized drainage of numerous lakes separated by hummocky rock ridges, muskeg and drift-covered areas. Local topography in the area is, however, extremely rugged, particularly south and east of Beaverlodge Lake, where resistant rocks form prominent hills and ridges extending as much as 180 m above lake level. Rock exposures are abundant and form over 50 per cent of the land area.History of Exploration and DevelopmentEconomic interest was first aroused by Tyrrell (1896) who described an occurrence of iron formation at Fish Hook Bay; however, subsequent evaluation of the deposit indicated it to be uneconomic."

Jan 1, 1986

By G. O. Allard, A. Gobeil

The Chibougamau area is the eastern segment of the MatagamiChibougamau greenstone belt. The Archean rocks of the area consist of two mafic-to-felsic volcanic cycles ( Roy Group) overlain by a sedimentary-volcanic sequence (Opemisca Group). The Roy Group volcanics are intruded by many coeval and comagmatic differentiated gab bro sills. The Supracrustal rocks of the Roy Group and Opemisca Group have been folded about north-south axes, refolded isoclinally about east-trending axes and metamorphosed to the greenschist facies. The same lithologies have been identified east of the Grenville Front at amphibolite grade. The first volcanic cycle consists of 3000 metres of porphyritic pillowed basalts and comagmatic gabbro sills (0batogamau Formation) overlain by a thin sequence of felsic pyroclastics, porphyritic dacites, and iron formation (Waconichi Formation). The Dore Lake Complex is a sill-like layered complex intruded in the upper part of the Waconichi Formation. The second cycle consists of 3600 metres of pillowed basalts and gabbro sills (Gilman Formation) overlain by a volcanosedimentary assemblage less than 1000 metres thick (Blondeau Formation). The Cummings Complex consists of the Roberge sill (dunite and peridotite) at the base, the Ventures sill (gabbro) and the Bourbeau sill (leucogabbro and quartz ferrodiorite) at the top. It is emplaced within the Blondeau Formation. The Opemisca Group sediments and minor porphyritic K-rich andesites (Stella, Hauy, and Chebistuan Formations) form narrow belts preserved in the synclines of the area. The Proterozoic rocks of the Chibougamau area consist of conglomerates, arkoses, and argillites with dropstones of the Chibougamau Formation. North of Chibougamau, the Mistassini Basin forms an elongate northeast-trending basin filled with sediments of the Mistassini Group. Conglomerates, sandstones, argillites, dolomites, stromatolitic dolomites, and iron formation are the principal sediments within the basin.

Jan 1, 1984