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In most instances, the preferred mining methods in steeply dipping narrow vein deposits are selective methods such as cut and fill or shrinkage. The main advantage of these methods lies in the higher degree of control over dilution that can be achieved. However, where ore body geometry lends itself to it, high yield bulk methods can also be attractive. Higher productivity (and the associated lower costs) and lower worker exposure are some of the significant advantages that have made such methods so popular. The Lapa gold mine located in North-Western Quebec uses the long hole mining method (with cemented rock fill) very successfully despite challenging ground conditions. This paper focuses on the experience of the mine with regards to drilling and blasting practices. Firstly, the reasons that prompted the selection of this mining method at Lapa are examined. Secondly, the challenges that the difficult ground conditions found at Lapa pose to drilling and blasting are discussed. Finally, the results of trials of different drilling and blasting strategies that were performed at the mine are presented with particular emphasis on the lessons learned.

Aug 1, 2013

By Nick Hazen

Many successful actions are required to bring a profitable extractive metallurgical operation into production. Competent process development performed within the project development schedule increases the chances of obtaining project financing and decreases the risk of engineering design errors being built into the commercial plant. The general sequence of steps in process development is well known: technology review, desktop studies, scoping studies, prefeasibility, and so on, with an increasing requirement for experimental evidence as the studies advance. This paper suggests principles for guiding process development work so that the efforts stay on track toward a smooth startup and a profitable commercial operation. It emphasizes closely aligning the research with the corporate goals of the mining company management, understanding the mineralogy and variability in the deposit, and guiding by flowsheet and material balance. Examples of hydrometallurgical process development leading to the early use of solvent extraction in the mining industry are given.

Jan 1, 2014

By I. Masters, K. Buban, M. Faris, M. Antonio, M. Collins

"AngloGold Ashanti Brasil, with assistance from Sherritt International Corporation, has recently commissioned a new autoclave for the pressure oxidation of refractory gold feeds at their Corrego do Sítio operation in Brazil. Design of the new plant, including feed acidulation, pressure oxidation, oxidized solids washing and solution neutralization circuits, was based on the results of test work conducted by Sherritt at their pilot plant in Fort Saskatchewan, Alberta. This paper describes the results of the pilot plant study as well as highlights of the design exercise.INTRODUCTIONAngloGold Ashanti Brasil (AGA Brasil) has recently commissioned a refractory gold pressure oxidation plant at the site of the original São Bento operation in Brazil. The design of the São Bento pressure oxidation facility was based on Sherritt technology; Sherritt carried out the original process development test work in the mid-1980s, provided a process design package and detailed specifications for critical pressure oxidation equipment and participated in the training of operators and commissioning of the plant. The São Bento plant was operated between 1986 and 2007, when the original ore body was exhausted (Silva et al., 2004). AGA Brasil purchased the facility from Eldorado Gold in 2008, with the intent of refurbishing the plant to process refractory gold concentrates produced from the nearby Córrego do Sítio mining area.Sherritt International Corporation has a long history in the development and application of commercial pressure oxidation and pressure leaching processes. Sherritt’s development of technology for the pressure oxidation of refractory gold ores and concentrates commenced in the 1980s in collaboration with Homestake for application at the McLaughlin project in California. This was followed by several commercial applications in Canada, Papua New Guinea and Brazil (Berezowsky et al., 1991). More than thirty pilot plant campaigns investigating the pressure oxidation of refractory gold ores or concentrates have been conducted by Sherritt since the 1980s, and projects with Sherritt contributions to the process development studies and/or engineering design account for about half of the commercial plants that have operated to date with this type of process (Collins et al., 2011a; 2011b)."

Jan 1, 2012

By Sunil S. Gandhi

"Uranium occurrences are widely distributed in tuffaceous-argillaceous beds and abundant rhyolitic volcanic rocks of the upper Aillik group, which is more than 3 km thick and over 125 km by 40 km in areal extent. They include partially developed Kitts and Michelin deposits, containing 1560 and 7366 t U respectively.Uranium occurs mainly as disseminated fine pitchblende grains in beds and lenticular stratabound zones, and rarely as coarse pitchblende aggregates and thin veinlets. The Kitts deposit and ten other occurrences are in the argillaceous-tuffaceous beds within a steeply dipping stratigraphic zone, less than 50 m thick and over 20 km long, at the base of the upper Aillik group. The occurrences hosted by the rhyolitic rocks, numbering over fifty and including the Michelin deposit, are in elongate structural-stratigraphic belts or zones, and are characterized by a pronounced enrichment of soda and depletion of potash associated with mineralization. The mineralized zones are affected to a varying degree by Hudsonian deformation, metamorphism and granitic intrusions.The uranium mineralization is interpreted as genetically related to the felsic volcanism, involving syngenetic deposition in argillaceous-tuffaceous beds and epigenetic emplacement in rhyolites. The volcanic activity occurred 1855 ± 5 Ma ago according to a preliminary U-Pb zircon date on porphyritic rhyolite. Pitchblendesfrom the Kitts and Michelin deposits and a few other occurrences in rhyolites have yielded nearly concordant dates in 1810 to 1730 Ma range. They reflect resetting of isotopic equilibrium at the time of Hudsonian deformation. Other isotopic data on pitchblendes and galena from veins and aggregates .in the south near the 'Grenville Front' indicate local redistribution of uranium and radiogenic lead at the time of Grenville Orogeny approximately 1100 Ma ago."

Jan 1, 1986

By W. A. Lang

"I.-IntroductionAn attempt bas been made in this paper to provide a basis for appraisal of the future of the coal briquetting industry in Alberta by outlining the processes used for briquetting various ranks of coal, by specifying the requirements of a briquetted fuel, by indicating .the status of the industry in the United States, by giving developments in Western Canada, by assessing costs of processing, and by discussing briquetting researches in progress. Much of .the detail bas been omitted since this might mask, rather than reveal, the more important phases of the problem. Reference will be made when possible to published articles where many of the details can be obtained.It should be stated at the outset that, in the writer’s opinion, there are three possible developments in Alberta as regards briquetting: (a) an expansion of the briquetting of the fines of • non-coking and coking coals of semi-anthracite, and of low and medium volatile bituminous rank; (b) the processing of the fines of high-volatile C bituminous coals; and (c) the upgrading of the lower rank high-moisture sub-bituminous coals. Details of the chemical and physical properties of these coals can be obtained in publications of the Research Council of Alberta (1, 2), and of the Fuel Research Station, Bureau of Mines, Ottawa (3).Semi-anthracite and low and medium volatile bituminons coals occur in the mountain areas of Alberta, where, during the upthrust of the Rocky mountains, the coal beds served as the sliding surface. This resulted in the coals being; crushed and consequently they contain a h1gh percentage of fines. In some cases they are high in mineral matter and require to be cleaned before being processed. However, the cleaning of fine coal is both difficult and costly. Both the amount of fines present in the mine-run coal and the amount of mineral matter associated with the coal have increased through the introduction of mechanized mining and through the recovery of coal by stripping operations."

Jan 1, 1950

By B. R. Johnston, K. D. Streeter

"ABSTRACTCoal Mountain Operations is the newest of Fording Coal’s operations although it is the oldest in terms of its historical production. In October, 1994, Fording purchased the former Corbin Creek/Byron Creek Mine. The mine is located in southeastern British Columbia, approximately 150 air kilometers from Calgary, Alberta. It was first developed in 1905 and has gone through a variety of owners in its 90-year history.This paper will deal with the remobilization strategy and the mining plans for the operation which are being implemented to make this operation competitive in the world export coal market. IntroductionIn October 1994, following a due diligence process, Fording Coal Limited purchased Coal Mountain Operations from Corbin Creek Resources, an employee group which had previously owned the mine. The purchase awarded Fording Coal Limited with 100% of the assets, and control of all the coal leases at Coal Mountain.The mine is located in southeastern British Columbia, southeast of Sparwood at the hamlet of Corbin, (Fig. 1).Rehiring of laid-off employees started in November 1994, with mining activities also recommencing in November. The coal preparation plant was restarted in December with one shift, went to two shifts in January 1995, and had four-shift, full-time operation in April 1996."

Jan 1, 1997

By P. G. Rueffel

"Natural deposits of sodium sulphate are the result of normal geological processes. They are world-wide in occurrence and are found in depressions in arid and semi-arid regions. Primarily, the sodium sulphate deposits of the prairies are post-glacial and differ from rock salt deposits, which originated from connate water (fossil sea-water). Sodium sulphate on the Canadian prairies occurs as brine or in beds of intermittent and/or permanent crystals. Most beds are contaminated with various amounts of silt, sand and decayed organic matter. Soluble impurities such as chlorides, carbonates and bicarbonates of sodium and sulphates of magnesium and calcium are leached out from the soil of the surrounding run-off area of the deposits.In this paper, the origin of sodium sulphate, and the physical and chemical aspects related to the development of the Ingebrigt Lake deposit are dealt with. The problems of garnering raw material, and of refining and de-hydration are discussed, with emphasis on the Ingebrigt Lake plant. The utilization of the ""Total Power Concept"" in a sodium sulphate plant is described. The principal uses of sodium sulphate are also discussed."

Jan 1, 1968

By C. O. Swanson

"OUR INTEREST in estimates of world reserves of lead and zinc is focussed mainly on the information they give about the sufficiency of metal supplies for the future. However, we soon realize that the estimates can be interpreted in several different ways. Accordingly, it is necessary to have some under-standing of the elements represented by a compilation of world re-serves, and we will start by examining the accuracy of the estimates and what they attempt to measure.Variations in Estimates of the ReservesIf we study the estimates of world reserves that have been published in recent years, we note immenediately that they vary over a considerable range. For example, an article by Shea in 1947 gave world reserves as about 36 million tons of lead and 60 million tons of zinc. Shea did not in elude the United States but I have added to his totals the estimates made by the Bureau of Mines for that country in arriving at the foregoing figures. For approximately the same date, the American Zinc Institute and the Lead Industries Association reported world reserves as about 50 million tons of lead and 77 million tons of zinc. A comparison of the two sets of figures shows a mean variation of 30 per cent. For individual countries the difference between estimates can be even larger. A few years ago the estimate of Canada's reserves made by the United States Bureau of Mines was 7.4 million tons of lead and 14.0 million tons of zinc, while the Gordon Commission reported 1 O. 7 million tons of lead and 26.0 mil-lion tons of zinc. In this case the mean variation was 55 per cent."

Jan 1, 1960

By D. Yuan, L. Yan, M. J. Collins, P. Kalanchey, I. M. Masters

ABSTRACT Pressure oxidation tests have been conducted by Sherritt for a refractory gold-silver project in China. The feed contained 39 g/t Au and 970 g/t Ag; the major gold-bearing minerals were pyrite and arsenopyrite. Because the feed contained a significant amount of silver, which can be refractory to cyanide leaching after pressure oxidation due to the formation of argentojarosite, the test program included investigation of methods to enhance silver recovery. The “lime boil” process proved successful and was incorporated into the flowsheet. Gold extraction from the lime boil product solids was 95–98%; silver extraction was up to 94%.

Jan 1, 2013

By J. A. Harle

Introduction When considering power in Alberta, there automatically come to mind ideas of either hydro or thermal generation, leaving in one's thought an uncertainty as to which one would propose. There is frequently an obvious source of power in some locations on our fastflowing rivers, the major possibilities being described in the report on Surface Water Supply and Water Power of Alberta issued by the Alberta Government in 1948, but it must be realised when reading that report that the sites so described will require extensive geological and other surveys before they can be exploited, and account must be taken also of the transmission distances involved in each instance. From a conservation point of view, where water power can be economically developed and power transmitted to the load centres, this should be done, and our thermal resources should be husbanded for our coming generations, especially if our water resources are falling owing to glacial shrinkage.

Jan 1, 1951

By R. Khanna, I. Mansuri, S. Devasahayam

"Recycling polymer based end-of-life materials as carbon resources for a partial replacement of coke/coal can make important contributions towards enhancing the environmental sustainability of steelmaking processes. An in-depth high temperature (1550°C) investigation has been carried on waste CDs/DVDs focussed specifically on char generation, characterization and dissolution into molten iron. The simultaneous presence of carbon and oxygen in polymeric chains on polycarbonate substrates resulted in the generation of a significant pore structure and exposed surfaces. Carbon dissolution studies into molten iron were carried out on the raw polymer as well on chars; high levels of carbon pick-up were observed in both cases after 15 minutes of contact at high temperatures. INTRODUCTIONOver the past sixty years, plastics have played an important part of our daily lives and are being increasingly used in all aspects of the global economy. More than 260 million tons of plastics are produced annually worldwide. Their rapid growth and extensive utilization with a short life span (such as packaging) has created a massive waste problem. Although the waste plastic component in municipal solid waste (MSW) amounts to only about 10 %, plastics have a high volume-to-weight ratio and these are generally not biodegradable. In Australia, ~19.20 % of plastics were recycled in 2009-2010 (PACIA, 2010); with the total consumption being estimated at 1,501,258 tonnes, 288,194 tonnes of plastics were recycled. There are serious environmental concerns with the two key waste management options, i.e. land filling and incineration, and there exists an urgent need for developing alternative recycling approaches. In this paper, we focus our attention on recycling waste CDs/DVDs polycarbonate substrates as a carbon resource in steelmaking.CDs/DVDs used for music/data/image are made from aromatic polycarbonate resin (hereafter abbreviated PC). This resin is also widely used as an engineering plastic in applications such as automobiles, mobile phones, notebook type personal computers, cameras & video cameras, electric & electronic appliances, fire equipment, life & living goods, roofing sheets, etc. High consumption and growth (~10% annually) of PC utilization is attributed to its excellent properties such as outstanding impact resistance, transparency, heat resistance, and dimensional stability. The molecular formula and composition of PC resin is given below:"

Jan 1, 2012

By J. Oyunaa, P. Munkhbaatar, A. Sarnai

"The molybdenum mining process used at Mongolia Erdenet Company is a selective flotation of molybdenite from the copper porphyry ores in which the extraction of molybdenum comes as a byproduct of the ongoing copper production.The mineralogical composition of molybdenum concentrate is 99.4% molybdenite (MoS2), 0.09% molybdenum oxide (MoO3), 0.52% powellite (CaMoO4) and wulfenite (PbMoO4) and content 47.76– 47.92% molybdenum, 1.5–2.67% copper, 0.04% renium.From compared solvents sodium and carbonate and ammonia are like extracted molybdenum than hydrochloric acid, which contained 96.23–97.72 p.c. of its total amount. Hence to take into consideration abundance, cheap and suitable for analysis and processing the molybdenum concentrate ammonia is choosing as a basic solvent. By direct evaporation of ammonia extract solution, we obtained ammonium ortomolybdate, which contains 73.47% MoO3. INTRODUCTIONMolybdenum occurs in the earth’s crust in an abundance of about 10–14%, mainly as molybdenite, MoS2. Small quantities are also associated with other metals having similar chemical properties. Thus wulfenite (PbMoO4) is found in oxidized parts of sulfidic lead deposits in many regions of the world; powellite [Ca(Mo,W)O4] is a calcium molybdate usually formed from the modification of molybdenite in deposits containing tungsten as scheelite (CaWO4) and tungsten substitutes for molybdenum up to about 10%. Ferrimolybdite (Fe2Mo3O12·8H2O) is the product of oxidation of molybdenite in the presence of iron (III) compounds. Molybdenite is the primary source of molybdenum. Should demand for molybdenum rise so that additional sources become necessary, wulfenite, powellite, and ferrimolybdite may become commercially significant. Molybdenum ore is mined by underground and open-pit methods. A typical primary molybdenum ore body contains 0.05–0.25% Mo, and secondary ore bodies (copper porphyry ores) average 0.3–1.6% Cu and 0.01–0.05% Mo. Flotation remains the preferred and almost exclusive method of upgrading the molybdenite mineral to an industrial-grade molybdenite concentrate containing 90–95% MoS2, the balance being gangue (Habashi, 1997)."

Jan 1, 2016

By E. Nolasco, J. Ouellet, T. Tikka

"Shaft bottom structural systems are used in underground mining to support transfer of personnel, equipment and ore to and from underground to the surface. This paper first summarizes the evolution of design philosophy from a concrete tower supported on a concrete plug to the current structural steel design arrangement with unlined shaft walls, clear shaft bottom area with only a concrete housekeeping pad. Then the paper reviews the design parameters, analysis and design, and construction methodology for this rather unique shaft bottom structural system consisting of three sets of hitch beams, with each having specific functional requirements. INTRODUCTION Shaft bottom structural systems are used throughout the world in underground mining operations to provide a means to support the transfer of personnel, equipment, materials, ore and waste entering and exiting a vertical shaft ready for transport to and from the surface via the hoisting system. The shaft bottom structural system, for the Service Shaft (SS) at the Jansen Mine, is designed to accommodate two skips, a personnel/equipment cage, counterweight, services, loading pocket, rope changing, arrestor system, crash (or catch) beams, access platforms, stairs and rope divider system. Stantec and BHP have engineered a unique structural steel shaft bottom system for hoisting system at a Potash Mine. The shaft bottom structural system connects to a fixed guide and cantilever bunton system, used in the vertical shaft (shaft barrel), above the shaft bottom. The geometry for the shaft bottom structural system, shown in Figure 1 a), features three sets of hitch beams, beams which span across the shaft excavation or barrel. At the top of the structural system are two upper hitch beams. These hitch beams support a 64 metre suspended rectangular braced tower (upper tower), complete with steel guides for the conveyances. The upper tower passes through the main station (potash or mining) level and then connects to the top of the arrestor (lower) tower structure via a sliding vertical connection. The potash level is supported by two hitch beams spanning the shaft and loading pocket excavations. The arrestor tower, a braced compression tower structure, is carried by a third set of hitch beams. Below the third set of hitch beams is a short suspended tower complete with access platforms, stairs and the rope divider system."

Jan 1, 2019

By R. K. Rajamani

Discrete Element Method simulation of charge motion in ball, SAG and autogenous mills has become a standard for design of mill internals, power draft evaluation, etc. Both two-dimensional and three-dimensional codes are being used. The two-dimensional code dominates the user market since the code completes a simulation in one or two hours. On the other hand, three-dimensional codes have been in the domain of specialists who can handle the complexity of the code and have access to parallel computing hardware. For the first time, this barrier is overcome via computing with graphic processing units (GPU). Commodity graphics cards now allow parallel computation with hundreds of processors. It is shown that the computational time has been reduced by a factor of fifty using GPU computing. Hence, SAG charge simulation results in three dimensions are achievable in a few hours using affordable desktop machines. The GPU computing shown here enables the three dimensional simulation into a manageable daily task for mill designers and researchers. On the technical side, the simulations can be elevated to a higher level of complexity to simulate breakage and transport. First, the speedup factor of fifty is established for the Nvidia GeForce GTX 580 graphics card. Next, four simulation tasks, consisting of AG, SAG and ball mills are reported. The simulation of AG and SAG mills are completed in less than 8 hours. The ball mill simulation with 1.25 million spheres is completed in 27 hours. In the near future, as the graphic card hardware advances the compute time can be halved.

Jan 1, 2012

By L. Li, K. Jiang

China is the world largest producer and consumer of zinc. Beijing General Research Institute of Mining and Metallurgy (BGRIMM) is one of major research and engineering institutes for nonferrous metallurgy in China. This paper (presentation) introduces the development of China’s zinc smelting industry, key production processes and main producers. The process research and development are reviewed as well as BGRIMM’s R&D activities in the last decade. China's refined zinc production was 4,829kt in 2012, accounting for 38.6% of world production. Primary production was 4,722kt. There are around 150 refined zinc producers in China. The traditional fluid bed roasting - leaching jarosite is still a dominant process for primary production and its production accounts for about 60% of country's total production. However, the direct leaching process is gaining market share. Seven direct leaching plants with 330kt/a capacity, including autoclave leaching and the Outotec direct leaching, have been put into production by June 2013. Five autoclave leaching projects with 590kt/a capacity are in the pipe line and are expected to be commissioned in 2014 and 2015. To cut the production cost and improve smelter economics, process research to optimize the production flow sheet, to improve the iron removal and to enhance the recovery of co-existed rare metals were carried out. The development trends of China’s zinc smelting industry from the view of cutting production cost, improving energy efficiency, increasing comprehensive utilization are discussed accordingly.

Jan 1, 2014

"The Hardy Cross algorithm offers a reliable method of solving network systems of fluid flow and has become widely used for solving water and ventilation flow networks. A limitation is that computational iterations and time to solve a network rises rapidly with the size of the model and modern detailed ventilation networks have typically grown to thousands of airways. Non-linear matrix solving methods can offer improved performance, however these are more complex and may be unstable if initial estimates are poor. This paper presents improvements that can be applied to the traditional Hardy Cross algorithm to greatly reduce iterations and solving time for large ventilation models. INTRODUCTION The Hardy Cross algorithm (Cross, 1936), was originally developed to solve water flow in city and urban pipe networks. Using principles of Kirchhoff’s electricity current laws, Hardy Cross developed an iterative algorithm for solving non-linear equations associated with network water flow. Traditional network analysis research refers to the various members of system networks as branches, nodes and meshes. This terminology has been changed in this paper to airways, junctions and loops respectively which are terms more familiar to engineers in mine ventilation. When Kirchhoff’s laws are applied to fluid networks, the following assumptions can be made: •The sum of fluid flows into a junction must equal the sum of fluid flows out of the junction.•The sum of pressure losses around any loop through a network system must be equal to zero.An iterative solution can therefore be achieved by initially guessing flow in a network, calculatingthe pressure losses around the network loops (Figure 1), and applying flow corrections using Newton’s method for each loop if the sum of the pressure losses does not equal zero. To solve the system, a loop must be defined for every segment or series of segments between a junction of 3 or more airways.The Hardy Cross algorithm has been used extensively for ventilation network analysis since the introduction of the first electronic computers (Tien, 1997), however numerous other variations and methods have since been developed through the use of matrices to solve the required system of nonlinear equations. Commonly used algorithms such as the Newton Raphson method (Brown, 1969), the Gradient method (Todini & Pilati, 1988), the Linear Theory method (Gupta & Prasad, 2000), and Coupled Network Solver (G. Danko, 2008) have found general use in fluid flow network solvers (Rossman, 2000). Despite poor and sometimes unpredictable convergence performance however, the Hardy Cross algorithm still has unique properties that make it attractive for ventilation models. Some benefits are:"

Jan 1, 2019

Risk management has taken on renewed vigor since the economic crisis of the late 2000s. The resources of governments, individuals, and corporations are being stretched to a point where only the most promising projects move forward. Risk management is a crucial part of the decision making process, yet it remains a broad term that includes disciplines from engineering to finance. A collaborative effort will be necessary to ensure that the most auspicious and appropriate projects are the ones moving forward. Risk management can be quantified to an extent by comparing the likelihood of an instance with the result of consequence of the instance occurring. In this manner it is possible to assign risk factors to instances and ultimately, begin to associate monetary value to the instance. Carbon sequestration is an emerging field that has a number of unique challenges. Risk management and mitigation must be an integral part of the overall picture. This begins with the planning and design phase, continues through implementation and production, site closure, and does not cease until termination of liability. The ability of carbon sequestration projects to successfully assess, mitigate, and recover from leaks will be a decisive characteristic of overall success. The costs of mitigation and failure will need to be analyzed on a test level, but will still need to be reliable enough to extrapolate to a commercial level operation. This paper will build a risk management profile based on case studies and field tests in Tennessee and Virginia. These tests are scheduled to commence in late 2013 and consist of small-scale injection tests in unconventional storage reservoirs with an emphasis on enhanced coalbed methane (ECBM) recovery and enhanced gas recovery. The ultimate goal will be to provide a clear and concise direction to move carbon sequestration from the test phase to commercial scale. While it is necessary from a risk management perspective to analyze all risk points, the scope of this paper will focus on pre-injection risk assessment for carbon dioxide (CO2) leakage potential. Despite the differences between the two tests, CBM compared to shale among other differences, a framework for analysis and mitigation can be developed pertaining to leakage risk. The probability of each type of failure will be assessed and analyzed, and plans to mitigate or reduce these risks will be reviewed.

Aug 1, 2013

By L. A. Wrigglesworth, A. S. Dadson

The orebodies of the Giant Yellow-knife mine occur in zones of schist, in an assemblage of typical Precambrian greenstones which form part of the Yellowknife Greenstone Belt. One of the most interesting problems at the mine concerns the fold-like attitudes assumed by the schist zones. The internal structure of the zones and orebodies provides much evidence of folding. A logical conclusion would be that the zones represent a single horizon which has been folded and drag-folded in the ordinary course of mountain building. However, surface mapping, and correlation of certain marker horizons, in underground work, indicate a homo-clinal succession of steeply dipping flows. If this concept of the geology is correct, the zones must cross-cut the regional strike at a small angle and, in the over-all aspect, the regional dip at a large angle. A mechanical interpretation of the zone structure is presented as a suggestion for the present until new evidence is found.

Jan 1, 1959

By J. F. Davis

Pegmatite dykes containing lithium minerals and beryl occur dose to the borders of intrusive masses of granitic rock in the Winnipeg River area of Manitoba. Both vertical and flat-lying dykes are present. Most of the pegmatites consist of zones, containing characteristic mineral assemblages, arranged more or Jess parallel to the borders of the dykes. Five important lithium minerals are present; each occurs in a separate zone, but all the lithium-bearing zones are situated toward the centres of the pegmatites. Spodumene is the most abundant and widespread of the lithium minerals and occurs as small crystals intimately intergrown with quartz. Beryl is not an important constituent of the lithium pegmatites, but when .present, occurs outside the lithium zones, toward the margins of the -dykes. Beryl is most common in dykes containing few or no lithium minerals. The mineral assemblage in the beryl zone of the lithium dykes is the same as that of the beryl dykes. The attitude and internal structure, particularly zoning, of the pegmatite dykes, and the texture and assemblages of the constituent minerals, have an important bearing on exploration, development, and mining of these pegmatites, and on the extraction of various mineral products from them.

Jan 1, 1958

By A. N. May

"This paper describes the present approach of the Mines Branch to the problem of measuring the stress condition in the interior of rocks surrounding underground openings. An instrument, which will be referred to as a stressmeter, has been developed at the Mines Branch to measure un-directional stress changes in absolute units. There are two modes of operation of this stressmeter. It can be regarded as a fixed instrument, in which case it is installed at the end of a diamond drill hole and left in position to record any subsequent stress changes taking place. Alternatively, three of the stressmeters can be used in conjunction with a trepanning opera-tion to allow the existing stress condition to be determined. The initial laboratory work and subsequent experiences in the field with the stressmeter are described. All the field development work on the stressmeter was made possible through the co-operation of Canadian Refractories Limited, Kilmar, Quebec."

Jan 1, 1960