Search Documents

By A. M. Ramadan

The composition of phosphate rocks, mainly used in manufacturing fertilizers, varies among deposits; therefore, phosphate rocks from different sources are expected to behave differently in acidulation processes. This paper examines the effect of preconcentration of phosphate ore from El-Sebaiya East, Egypt, using flotation on uranium leaching. A high-grade ore sample (27.3% P2O5, 168 mg/kg U) supplied by the Al-Nasr Mining Company, was subjected to reverse single-stage flotation to separate carbonate from the phosphate sample. Subsequently, P2O5 and U concentrations were 32.2% (92.1% recovery) and 225 mg/kg, respectively. After the leach process, the U concentration in the liquor was 319 mg/L.

Jan 1, 2014

By C. M. Anson

This paper describes the progresses used in the manufacture of steel wheel-centres, tyres and axles at the works of the Commonwealth Steel Products Co., Newcastle, N.S.W., Australia. The plant is adjacent to the Northern railway and consists of three main buildings, namely: the foundry, the forging and rolling shop, and the machine shop. The foundry contains a 6-ton Heroult electric furnace, together with all necessary mechanical appliances for moulding. Reheating furnaces, steam hammers and tyre rolling mill are installed in the forging shop. The machine shop contains lathes, boring machines, and hydraulic presses. Until this plant commenced operations all wheels used in Australia were imported, previ.ous to the war, from England and Germany, and latterly from England only. Besides being of great benefit to the country in that there is now a domestic source of supply of these articles, there is also the advantage of retaining the home market; and in addition, a small portion of the population are now engaged in highly technical occupations requiring a great degree of skill. The plant began to operate in October 1919, and by 1921 was in a fair way to meet the domestic demand for those articles of railroad equipment which it manufactures.

Jan 1, 1925

By Bruno Lafrance

Abstract - Quartz veins at the Mufferaw gold prospect and Komis gold deposit, northern Saskatchewan, are examples of oblique-extension veins that crystallized in shear and tensile fractures, which propagated and then opened oblique to their walls during a single continuous deformation event. The Mufferaw gold prospect consists of an interlinked mesh of conjugate shear fractures, tensile fractures, and veins. Oblique-extension veins crystallized in conjugate shear fractures, which opened during dilation of intersecting tensile fractures under the same far-field stress system. At the Komis gold mine, tensile and dextral shear fractures cut across granodiorite dikes. The tensile fractures formed perpendicular to the dike margins during stress transfer from the less-competent country rocks to the more-competent dikes. During extension of the dikes oblique to the bulk extension direction in the country rocks, the tensile fractures were reactivated as sinistral shear fractures. The reactivated tensile fractures and dextral shear fractures opened oblique to their walls, parallel to the bulk extension direction, and were sealed by the deposition of oblique-extension veins during the same deformation event.

Jan 1, 2004

By Brian Hart, Hong Zhong, Liuyin Xia, Kyle Douglas

"The application of hydroxamic acid as flotation collectors is fast becoming of significant interest for the selective flotation of oxide minerals along with upgrading oxidised based metal ores and minerals. In the hydroxamate molecule, both O and N atoms in the -CONHOH group are identified as coordination atoms in many complexes and their characteristic structure determines the strength of the chelation complex between the hydroxamate and metal ion. The chelating performance of hydroxamates with transition metals including Cu, Ni, Zn, Fe, Cr, Mn and Co, the alkaline-earth metals (Be, Ca) and heavy metal (Pb) has been studied. Cytec has developed and patented a range of alkyl hydroxamates as flotation collectors for oxidised base metal sulphides, metal oxide minerals and precious metals. This paper introduces two new structures of hydroxamate collectors (Cyclohexyl and 4-tert-butylbenzoyl hydroxamates) and evaluates their characteristics relative to alkyl and benzoyl hydroxamates. Laboratory small-scale flotation tests were conducted with ilmenite and wolframite. The use of 4-tert-butyl benzoyl hydroxamate resulted in a best flotation performance for ilmenite. A relatively low cyclohexyl hydroxamate dosage was required in the flotation of wolframite to obtain comparable results to the alkyl and benzoyl hydroxamates. It is also shown a significantly improved flotation performance with 4-tertbutyl benzoyl hydroxamate in the flotation of ilmenite plant ore in comparison to the oleic acid or fatty acid collectors typically used for ilmenite flotation.INTRODUCTIONHydroxamic acid has been reported as an effective collector in small-scale flotation tests for a wide variety of oxide minerals and ores including copper (Lee et al., 1998, Lee et al., 2009), iron (Quast, 2000), tin (Sreenivas and Padmanabhan, 2002; Wu and Zhu, 2006), tungsten (Marinakis and Kelsall, 1987; Xia et al.,2004), and rare earth metal minerals (Ren et al., 1997; Pradip and Fuerstenau, 1991; Assis et al., 1996; Pavez et al., 1996; Zheng et al., 1996; Chen et al.,2005).As part of our previous research project, a selected suite of hydroxamic acid collectors including fatty, aromatic and modified hydroxamates (naphthoyl, cyclohexyl, benzoyl, octyl, 4-tert-butyl benzoyl, salicylic hydroxamates) were tested in order to examine their potential for recovery and selectivity of rare earth minerals. In these tests it was shown that the flotation performance with the hydroxamate collectors was significantly better than the phosphoric acid collectors on no slimes removed samples (Brian, et al., 2014; Liuyin, et al., 2014 and unpublished internal technical reports). Furthermore the tests revealed that for most of the hydroxamate reagents tested, their dosage requirements to achieve recoveries at the same levels was less than that for the phosphoric acid collectors. Recovery of both La and Ce was significantly better for the salicylic hydroxamate and that Nb, Y and Zr recovery were favoured by the octyl and benzoyl hydroxamates (Brian, et al., 2014; Liuyin, et al., 2014). Comparison among the hydroxamate collectors showed that the flotation and recovery performance of cyclohexyl (CHH) and 4-tert-butyl benzoyl (TBH) was not as good as the other hydroxamates for rare earth recovery."

Jan 1, 2015

By K. H. J. Clarke

SINCE the beginning of this century the non-ferrous mineral industry has contributed $17,809,-000,000 to the economic growth of Canada. To contemplate the vast amount of investment capital required and the resultant beneficial distribution of these billions of dollars for labour, transportation, supplies, taxes and dividends, challenges the imagination. It is the purpose of this paper, (a) to trace the development of the industry since its formative period to the present; (b) to discuss the current situation and problems; and ( c) to attempt to peer into the hazy future. Although there are 21 metals currently being produced in Canada which are classified as non-ferrous, or as alloying metals, copper, lead, zinc, nickel-the metals which will be discussed in this paper-constitute almost 60 per cent of their total value. ;The story

Jan 1, 1961

By S. Goodman

Successful exploration for and exploitation of a mineral deposit requires an accurate understanding of the deposit architecture in 3D, and of the development of the mineralizing system through time, which requires a thorough comprehension of the structural framework of the deposit. The integration of geological, geophysical and geochemical datasets to arrive at a 4D structural framework is well-established and has been successfully applied by SRK Consulting in projects from deposit to regional scale. In some cases, we can go beyond this, applying the SEEBASETM technique, which utilizes a ?bottom-up? approach to basin analysis. SRK?s approach primarily relies on the interpretation of magnetic and gravity data, calibrated with many other datasets including mapped geology, topography, event histories, wells/drillholes and seismic data. The SEEBASETM model is a culmination of this data integration and is produced through an iterative process of structural interpretation and geophysical modeling, where an interpretation of basement composition and 4D structure is used to constrain depth-to-basement geophysical modeling, and the modeled depths are then used in conjunction with the structural interpretation to constrain contouring of the basement topography. The result is a rigorously calibrated, 3D view of the basement surface, which can be used to understand the basement and basin architecture, and thus serves as a predictive exploration model. This technique, which was developed for use in the petroleum industry, is now finding success as a predictive tool in mineral exploration.

May 1, 2003

By Ralph D. Parker

THE subject matter of this paper will be primarily restricted to the metallic mineral industry, which last year was responsible for almost 60 per •Cent of the total value of Canada's mineral production. It has been written that, in the broad sweep of eternal time, sixty years is as transient as a flicker of lightning in a summer night's sky. In the history of mankind and human endeavour, however, six decades can encompass momentous events and far-reaching •circumstances, all of which affect the lives of men and change the destiny of nations. This observation is con-firmed very positively by a study of our Canadian mining history, from either the broad viewpoint of human progress or the more specialized viewpoint of national economy. The past sixty years have witnessed vast changes in the economic importance of mining in this country's affairs, and also in the technology of the industry. Mining has emerged from the days of rule-of-thumb practice and is now taking on the stature of a highly diversified science.

Jan 1, 1962

By Gheorghe Marin, Franco Chiesa, David Levasseur, Bernard Duchesne

Over the past 20 years, pressure die casting has evolved to a point where structural parts can now be produced by this process. This has been made possible by the development of vacuum die casting and by the development of die-castable, low iron content alloys. This resulted in the production of low porosity, weldable die-cast parts on which heat treatment may be applied. In the present paper, the influence porosities on the tensile properties of as-cast A360 tensile test bars was evaluated. This was done by casting 24 clusters, comprising three 6mm diameter test bars each, in a 280T cold chamber pressure die casting machine after a steady dynamic equilibrium had been reached. Modeling of filling allowed to explain the differences in porosity observed in the 3 samples of a same cluster while the results of solidification modeling were related to the microstructure. Tensile samples were radiographed on a real time X-cube apparatus and separated into 2 lots: samples where no porosity defect were visible and samples with visible defects. By measuring the tensile properties of the 2 lots it was possible to quantify the drop in tensile properties brought about by porosity, which is the most common defect observed in pressure die-cast parts.

Jan 1, 2015

By D. A. Rhys

"The Red Bluff porphyry is a tabular 2 km long north-west trending Early Jurassic quartz diorite to monzodiorite body that intrudes a folded Triassic greywacke sequence in the lskut River area, northwestern British Columbia. The porphyry is 500 m to 800 m northeast of the Snip orebody, which is a southwest-dipping shear-vein, termed the Twin zone that contains approximately 35 tonnes of gold.The intrusion associated with the mineralization is characterized by 0.3 cm to 4 cm phenocrysts of K-feldspar in a mediumgrained plagioclase porphyritic matrix. It is overprinted by pervasive sericite + quartz ± K-feldspar ± biotite (potassic) alteration characterized by intense stockworking of quartz veins containing magnetite--hematite bands. This assemblage is cut successively by quartz veins with minor iron-oxides and pyrite, and by younger pyrite veins with phyllic envelopes. The system is gold-rich but copper-poor, with typical grades between 0.25 g/t and 0.6 g/t Au, and 0.1% and 0.2% Cu. All styles of alteration and veining have similar abundances of these metals. Where southwest- and north-east dipping shear zones are developed in the porphyry, veins of all types are sheeted and foliation parallel. These sheeted zones are interpreted to be syntectonic. Asymmetric phenocrysts, folded veins and oblique foliations developed in the 130 haulageway of the Snip mine imply oblique normally-directed shear on the southwest-dipping foliation.The adjacent Twin zone is a high-grade auriferous shear-vein system that is internally banded with: (1) carbonate-chlorite-biotite veins, with textures indicating formation at least partially by wallrock replacement, and (2) dilatant quartz-sulphide veins. Veins commonly have potassic alteration envelopes that contain biotite ± calcite ± K-feldspar. The zone is highly deformed and schistose, with numerous kinematic indicators including shear bands, asymmetric folds, rotated porphyroclasts and oblique foliations that indicate a normally-directed shear sense which is parallel to that indicated by fabrics within the porphyry.Precious and base metal veins within 2 km or 3 km of the Red Bluff porphyry are zoned. Veins and shear-veins proximal to the intrusion, such as the Twin zone, are typically enriched in gold, copper and molybdenum, and have potassic alteration envelopes dominated by biotite. Distal veins usually contain relatively abundant zinc and lead and have sericitic alteration envelopes. Structures of both types have an Early Jurassic galena Pb-Pb isotope signature.The similarities in structural fabrics and alteration histories in both the Twin zone and the porphyry, the zoning of the vein systems in the area, and the apparently concordant Early Jurassic zircon U-Pb age from the porphyry and galena Pb-Pb dates from the Twin zone and surrounding vein systems suggest that intrusion, semi-brittle deformation and a large mineralizing hydrothermal system were closely related temporally and genetically."

Jan 1, 1995

By P. Marcotte, G. LeBlanc, S. Ouellette, J. Boutin

"To characterize noise and vibration sources of different types of mining equipment used in underground mining, the authors performed a study in eight Quebec mines on 28 pieces of equipment. This paper presents the procedure followed to select the equipment to be evaluated, and the low-cost acquisition system developed to perform multichannel time-domain data acquisition in harsh environments. It also presents the results obtained for the noise level produced by the equipment and for handarm and whole-body vibration exposures.RÉSUMÉ Dans le but de caractériser les sources de bruits et de vibrations de divers équipements miniers utilisés sous terre, les auteurs ont étudié 28 équipements dans huit mines du Québec. L’article présente la procédure suivie pour choisir les équipements à évaluer ainsi qu’un système multicanal à faible coût développé pour acquérir des données dans des environnements difficiles. Il présente aussi les résultats obtenus pour les niveaux de bruit produit par les équipements et pour les expositions main-bras et du corps entier aux vibrations."

Jan 1, 2015

By R. D. Brown

"AbstractIn order to raise the enormous amounts of capital which will be essential for the development of Canada's mineral and petroleum resources, this country's resource industry must be permitted to earn an acceptable rate of return. The existing tax regime, with its high rates, complexities and misdirected incentives, presents a serious obstacle to our resource industries in their development of Canada's immense , but increasingly lean, resources. Government tax and other policies are not the only cause of the crisis now facing the resource sector in Canada, but a reformed tax system, with stable and reasonable tax burdens, is required if Canada's resources of minerals, oil and natural gas are to continue to contribute in the future, as in the past, to our national well-being.An independent task force, organized under the auspices of the Canada West Foundation, has recently completed a wide -ranging report: on the future development of Canada's mineral, oil and gas resources. This five-volume report, completed after almost two years of research and study, concludes that Canada •is facing a major crisis •in the development of our resources, It states that unless corrective action is taken now, mineral production and exports could decline drastically after 1985, at the same time that Canada would face massive bills for imported oil because of inadequate and declining production.The task force, chaired by the author of this article, has put forward recommendations for a fundamental shift in both federal and provincial policies in order that Canada's mineral reserves can be developed in the national interest. This article consists of excerpts from the summary of the task force's report."

Jan 1, 1977

At the end of a century of mining education in South Africa, it is appropriate to reflect on the past, take stock of the present and ponder the future of mining education. While it is likely that changes in the mining industry will generate an increased demand for mining graduates, the number of suitably qualified applicants to study mining is worryingly small. While good progress has been made in unifying the educational system that previously provided schooling on a racially separate basis, it appears that a decade or more will be required to raise competency levels in mathematics, science and English, and this paper describes the process as it affects mining engineering programs. It also describes the initiatives currently being undertaken by the University of the Witwatersrand and the mining industry to ensure that the South African industry receives an adequate flow of well-qualified mining graduates, despite more than 70% of the intake coming from severely disadvantaged educational backgrounds.

Jan 1, 1999

By H. Rozovsky

"AbstractThis paper discusses the methods of handling air in a large asbestos mill presently being completed at the Jeffrey mine of the Canadian Johns-Manville Company in Asbestos, Quebec.The mill, being the largest single asbestos producer in the world and capable of handling over 14,000 tons of ore per day, requires vast quantities of air. A minimum of 2,500.000 c.f.m. is required or about 10 tons of air for each ton of ore milled.Short descriptions of the process and systems requiring this air are given, followed by details of the fans and filters which make up the heart of the mill.This 'draw through' system, located on the top or 12th floor, is an automatically .controlled volume-pressure system creating the required suction to draw .air throughout the mill building and its numerous air systems.The dry mechanical method of milling develops enormous quantities of airborne dust and fibre. A section of this paper is devoted to a description of the multiplicity of dust systems within a system to control, filter, and remove this dust.Finally, the paper describes the method of returning the filtered air to the• working floors or to the outside, with some notes on heat, humidity and dust counts.IntroductionGeneralTHE discussions in this paper deal only with operations where air movement is involved. No attempt is made to delve into production methods.The Jeffrey mine of the Canadian Johns-Manville Company, located about 100 miles east of Montreal, is the largest single asbestos producer in the world, being responsible for over half of Canadian asbestos fibre production."

Jan 1, 1955

By S. H. Ward

An account of a new method of investigating the electrical .properties J the earth's crust is presented. The method, called AFMAG, employs, as a source, natural alternating magnetic fields of audio and sub-audio frequencies. Measurements of the distortion of these fields caused by geological features are made with the aid of search coil detectors at several discrete frequencies. Many results of field surveys made with the method are presented and they illustrate its advantages and limitations when applied to the search for massive sulphide mineralization. The advantages far outweigh the limitations and in fact indicate that a major breakthrough in geophysical exploration technique and instrumentation has been made.

Jan 1, 1958

By T. G. Hawkins, T. M. Naciuk

"The Katie Cu-Au deposit is situated in southeastern British Columbia, 425 km east of Vancouver. The deposit is a member of the alkaline group of porphyry Cu-Au deposits associated with potassically and propylitically altered andesitic volcanic rocks.The Katie porphyry system occurs in mafic to intermediate alkaline volcanic rocks of the Lower Jurassic Elise Formation of the Ross/and Group. Host metavolcanic rocks include andesitic to basaltic flows, flow breccia, massive fine tuff and crystal tuff Gabbroic intrusions alternate with the volcanic rocks in drill core. The lack of chilled margins and shear contacts, as well as their similar composition to the volcanic rocks, suggest that the gabbro was synvolcanic.Alteration exhibits a zonal pattern spatially related to zoned porphyry-style mineralization. Propylitic alteration is common and assemblages consist of epidote, chlorite, sericite and calcite. Potassic alteration zones are accompanied by elevated copper-gold grades and are composed of K-feldspar, plagioclase, quartz, biotite and chlorite. Narrow drillhole intervals of secondary magnetite, generally less than 2 m across, occur above the potassic alteration zones. A thick oxidized cap lies above the mineralized zones, although only local supergene enrichment has been identified. The lack of supergene enrichment is perhaps due to intense near-surface fracturing and leaching from a high energy groundwater environment.Sulphide mineralization consists mainly of pyrite within the propylitic halo, and pyrite and chalcopyrite with trace pyrrhotite, sphalerite, tetrahedrite, bornite and molybdenite within the potassic alteration core. Malachite, azurite and traces of chalcocite occur within the oxidized cap.Discovery and exploration techniques have included airborne geophysics, regional stream sediment sampling, prospecting, geological mapping, ground geophysical surveys, soil sampling surveys, and diamond drilling. Two primary targets of porphyry copper-gold mineralization have been identified by exploration. The Main zone strikes northwest, has an apparent true thickness ranging from 70 m to 135 m, and is a minimum of 500 m in length. The 17 zone strikes northwest, has an apparent true thickness of 90 m, and is a minimum of 300 m in length. The two zones are defined by grades that generally exceed 0.2% Cu and 0.25 g/t Au. Both zones are open along strike and to depth."

Jan 1, 1995

By K. U. Kainer

Magnesium and its alloys as the lightest available construction metal offer a wide range of opportunities for the usage in transportation industries, especially Magnesium wrought alloys with their improved mechanical properties show a high potential for structural applications, While magnesium cast components have found their application the interest is now spreading to wrought alloys due to the possibility to get even more homogeneous and better properties compared to cast parts, Therefore alloy and process development especially for extruded and sheet material is a main concern to enhance the application of Magnesium wrought alloys, Castings are still form the majority of applications of magnesium alloys, although efforts to develop adequate wrought alloys have increased, In the presentation, the alloy requirements for processing of cast and wrought alloys will be discussed, The various processing routes and alloy compositions result in specific microstructures and properties which determine the potential use of these alloys, Today, the spectrum of available alloys covers standard alloys as well as alloys for use at elevated temperatures, The trend will be to further diversify the alloy compositions and to improve the alloy properties, Areas of concern still remain the wrought processing and the high temperature (creep) and corrosion properties of magnesium alloys, Examples of recent developments in these sectors will be given, The presentation will also provide an overview of the historical and current use of magnesium and an outlook on future applications.

Jan 1, 2006

By K Belanger, J. Mclachlan, F. Stober, G. Norval, B. Snider, A. Munsch, T. Koehler, E. Piantino, J. Carlos Queiroz

The project to rebuild the smelting furnaces at the Anglo American - Barro Alto ferronickel smelter, located in Goias, Brasil, was initiated in September 2013. To optimize the capital cost, while maximizing furnace integrity and robustness, a design basis giving flexibility to ore composition variation was developed in order to ensure sustained nameplate production. The resulting capital efficient, fasttracked project execution was accomplished through the creation of an integrated project team of Anglo American and Hatch through FEL 3 and FEL 4 phases of the project. The integrated team addressed the project challenges through a cooperative and versatile approach, created by access to knowledge, experience and systems in both Anglo American and Hatch. The team could operate at an optimized speed of execution, as demonstrated in the FEL 3 and FEL 4 completion durations, as well as efficiently mitigating any risks of increasing cost or delaying schedule by utilizing lessons learned and team knowledge from Anglo American on the original green-field project and Platinum smelters and Hatch on similar reference ferronickel furnace rebuilds. Other critical drivers of project cost minimization and revenue loss/generation (considering production revenue of each furnace) are scheduled durations for construction, commissioning and ramp-up. The integrated team commenced construction, commission and ramp-up planning almost one year in advance of the shutdown and this paper will discuss the strategies developed to reduce risks and optimize the construction schedule to mitigate revenue loss and optimize ramp-up time to sustained operation at nameplate capacity.

Jan 1, 2015

By G. A. Kosick, G. S. Dobby

"This paper presents the principles and application of a recently developed control system for flotation columns and column circuits. The control system uses triple pressure sensors to directly sense zone densities and level, and to help in characterizing the operating behaviour of individual columns. A complete expert system development tool is incorporated within the system to provide the facility for full operator training, an on-line help facility, and a means for incorporating the column behavioural patterns into decision making rules. The system is configurable to any number of columns and can be run in either supervisory mode or direct control through Minnovex PIO software. Additional process signals can be interfaced with the system if desired. Operating experience with the control system on the Minnovex column flotation pilot plant is described.I: INTRODUCTIONColumn flotation cells have been more difficult to control and are more sensitive to circuit changes than conventional mechanical flotation cells. This susceptibility encouraged investigation into various types of control strategies ranging from inexpensive single pressure measurements for level control, to highly instrumented and expensive systems using a variety of control methods.Flotation operators, in many cases, do not understand the column control philosophy or have not been trained to deal with this new type of cell. Some operators have subsequently absolved themselves of the column operating responsibility. Some column cells, for example, have run for hours with slurry pouring over the top or no froth coming off at all.ColumnEX is a column flotation control system which was developed from the viewpoint of an operating shift foreman who wishes to:1. control the column or column circuit through a genuine understanding of what is happening inside the columns, and2. to share this knowledge with his flotation operators and be available to guide them through times of circuit upsets."

Jan 1, 1990

By J. Budac, R. Krentz, P. Cordingley, G. Freeman, M. E. Chalkley, H. Scheie

Pressure hydrometallurgical unit operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation for fifty years. This paper traces the history of Sherritt from its origins in northern Manitoba, and the development of the first hydrometallurgical nickel-cobalt refinery in 1954, utilizing pressure hydrometallurgy, to the modern day refinery. Sherritt's involvement with pressure hydrometallurgy during the past 50 years has included the operation of the refinery, the development and licensing of technology, incorporating pressure hydrometallurgical unit operations, to more than 30 companies worldwide, the joint venture at Moa, Cuba involving both leaching and precipitation at elevated temperature and pressure, and the production of specialty metal powders. Developments in each of these areas are reviewed.

Jan 1, 2004

By E. G. Charlesworth, M. J. Robertson

"Abstract - Gold mineralization in the Main Reef Complex at Sheba Gold Mine is hosted within shear zones in a sequence of shales and greywackes of the Fig Tree Group. Competency contrasts between these rocks and a steeply dipping chert unit provided a locus for the development of right lateral steeply dipping shear zones. A set of flatter dipping shear fractures crosscut these zones with their intersections defining a system of en échelon ore shoots.Mineralization is both of vein type and disseminated strata-controlled replacement type. The latter occurs mainly within the wall rocks to the shear zones. Arsenopyrite and pyrite are the major sulfides, with arsenopyrite being confined largely to greywacke beds and pyrite to the more iron-rich shale units. Gold was introduced, together with minor sphalerite, pyrrhotite, chalcopyrite and early arsenopyrite, toward the end stages of a first pyrite phase. The mineralizing fluids were introduced along dilated cleavage planes and, emanating from these, produced a series of replacement fronts. Mineralization was syntectonic to late tectonic and occurred under conditions of progressive deformation, resulting in sulfides which are concentrated in the hinges of shear-related folds and semi­ massive sulfides within tension fractures which are folded, attenuated and fractured .An analysis of the structures shows a sequence of events in which an initial ductile simple-shear event with a steep sense of movement was succeeded by a more brittle strike-slip event. Mineralization is temporally related to the latter. This evolution in structural style was probably related to reactivation of the Sheba Fault as a transcurrent fault during emplacement of large granitoid bodies."

Jan 1, 1994