Search Documents

By D. M. Muir

Many plants produce iron(II)/(III) waste liquors which must be treated by neutralisation and precipitation to remove the iron. Iron can be precipitated as crystalline goethite or jarosite by controlled oxidation at low pH and as magnetite by controlled oxidation at high pH, but only at elevated temperatures (>70°C). This study focuses on the characterisation and settling properties of the iron oxides produced at ambient temperatures using various neutralising agents in order to improve the performance of thickeners. It was found that two-stage addition of caustic to FeC12 solutions produced a fast settling material characterised by Mossbauer spectroscopy and XRD as maghemite and magnetite. However, lime and magnesia additions resulted in more ferrihydrite formation and much lower settling rates because of the enhanced oxidation of Fe(II) by air. Settling rates decreased significantly as the proportion of Fe(III) to Fe(II) in the liquor increased. The mechanism of iron oxide precipitation is discussed together with some reasons for the different behaviour of the neutralising agents.

Jan 1, 2006

By B. Samanta

Abstract - Ore reserve estimation, based on sparse drill hole data, was conducted for a placer gold property in Nome, Alaska. A problem with sparse data is that random subdivision of the data into modelling and evaluation subsets (as is commonly done) becomes a problem, as random selection may result in biased/skewed subsets. Therefore, a technique that combined data segmentation with genetic algorithms (GA) was applied to divide the samples into three equivalent subsets: training, validation and testing. Data segmentation was done on the basis of the distribution of gold values. Neural network and a variety of kriging techniques were used to estimate gold grades. A multi-layer feed forward neural network along with "early/quick stop" training was used for neural network modelling. A comparative evaluation of kriging and neural network methods was then performed. The results revealed that neural network was generally superior to the kriging techniques for gold grade estimation in the Nome deposit.

Jan 1, 2002

This paper aims to increase our understanding about existing capacity-building approaches and their implications for obtaining a social license to operate in the mining industry. The notion of ?capacity building? is gaining increasing currency in the mining sector in developing countries due to a rapid rise in the globalisation of mining operations. Capacity-building is conceived here as a process that lasts after the mine-cycle, intended to provide local mining communities with tangible skills and knowledge to gain meaningful employment in mining or other industries relevant for the local economy. Building community capacity to understand and effectively respond to these transformations is vital for obtaining a social license to operate, as it promotes sustainable and locally relevant development. Accountability mechanisms such as global norms and international standards increasingly highlight the need to build capacity among stakeholders, particularly among local communities adjacent to mining operations. International frameworks and mining companies have embraced the notion of capacity-building as a driver to assist corporate social and operational performance. However, this narrow understanding of capacity-building through the prism of corporate social responsibility and ?best practice? is preventing the industry from meaningfully impacting communities and maintaining a social license to operate. This latter notion is being widely embedded across multiple industry sectors, as a social and economic reward from mining companies to compensate communities for natural resource extraction and gain social acceptance. Although both concepts are widely recognised in the minerals industry, insufficient attention has been paid to the implications of applying a top-down (mining-orientated) or a bottom-up (community-orientated) capacity-building approach for obtaining a social license to operate, or indeed how these two concepts are linked and applied in practice. At times, communities lack the necessary capacities in the form of education and skills to deal with mining-led livelihood transformations. This is preventing both mining companies and communities from forging sustainable livelihoods and responding to mining-led livelihood transformations, a situation that is creating discontent among communities and reducing the possibility of obtaining and renewing a social license to operate for the industry. Based on a review of current scholarly debates, accountability mechanisms in the mining industry and fieldwork findings in Colombia, this paper will contribute to an understanding of the implications of existing capacity-building approaches that support a social license to operate.

Aug 1, 2013

By X. (Mike) Yao

Rock mechanics engineers must provide ground support designs that ensure a safe underground working environment. Unexpected falls of ground are unacceptable while ground support systems must be adequate. Ground support must be economic for the area supported and the time frame the opening is in use. While numerical modeling can be used for ground support design, empirical models are still the common useful design tools. Empirical models are best developed and improved from local experiences although some models, such as Stability Graph (Potvin et al, 1992), are in extensive use by the Canadian mining industry. To determine the adequacy of ground support practices at HBMS, a database of 50 fall of ground case histories between 1985 and 2001 was compiled. For each failure, the recorded data included: location, rock type, rock mass conditions, opening and failure geometry, installed ground support and failure mechanism. An analysis of the database was done to obtain an understanding of failure frequency association with rock types, stope geometry and installed ground support, and to assess what support design changes were necessary. The paper describes changes made to ground support and mining practices during the last five years, and the formation of new ground support standards and practices which have been successful in reducing ground falls while providing improved, efficient and economical ground support.

May 1, 2002

By Bahram Samani

The Bafq - Saghand ore belt (metallogenic zone) is the main region, where the major discovered Uranium resources are located. This belt is a unique Upper Precambrian terrane experienced Katanga ? Pan African tectono ? thermal events. The oldest sialic crust was formed during the middle Proterozoic and followed by K-granite intrusions of Lufilian Cycle (850-800 M.Y.).This event caused Tectono ? Magmatic ? Activization (T.M.A) characterized by intracontinental rifting and associated ore formations. This zone was considered as an iron ore belt in 1960s ? 1970s, and U ? Th ? REE belt in 1980s ? 1990s, but by new discovered of U ? Mo (Co, Au, As, Cu) mineralization is assigned as a U - Polymetal zone, hosting the full sequences of iron oxide (Cu, Au, U) ore forming groups. On the basis of detailed investigations this zone is characterized by the following peculiarities: This zone is the vestigial vessel of Gondwana basement, where the oldest granite and the first platform clastic cover is exposed. This zone is marginal part of Precambrian continental crust, consolidated in 1.3-1.0 B.a. The sub mature continental crust experienced Lufilian Orogenic and Katanga ? Pan African Tectono ? Thermal event by intercontinental rifting, and ore mineralizations. The ore forming stages were sequential processes, started by enriched mantle derived metallogeny, and ended by interaction of silanes/ HACONS (derived from outer core) with crust. The magnetite- apatite (REE, Ti) metallogeny developed from alkaline- ultrabasic magmatic differentiation, capable to from Au- Ni- Sulfide intrusive massifs during 850- 800 Ma. Degassing of silanes/HACONS from deeper level, not only caused mantle enrichment, and plume upwelling as a frontal load, but also played the main role to develop regional Si (-Na-K-Mg-Ca-Co3) metasomatism, and formation of U- Th- Ti- REE- (apatite, magnetite) deposits. The latest (583-510 Ma old) felsic magmatism was major IGU from U-Mo (-Co-As-Au-?Cu?) hydrothermal vein- type deposits. The albitite- type U- Ti- REE (Th) mineralization could be formed by interaction of ascending, and descending solutions along the deep- rooted structural conduits.

May 1, 2007

By Sophia Wong

Nickel is used in a wide variety of applications from consumer goods to industrial uses. In many of these uses, nickel contributes to the environmental attributes of the product. The challenge, however, is measuring that contribution, comparing it to the environmental cost of production, and communicating the role of nickel to the customer in a way that is easy to understand. This paper presents the Nickel Institute?s approach to climate change as a global commodity industry association, and discusses where we stand with regard to some of these key questions. It also identifies issues for the nickel industry moving forward ? challenges that are likely to be common to other commodities.

May 1, 2009

By The Honourable George Prudham

"I AM PLEASED indeed to be present with you here today and to be taking part in the proceedings of your convention. You have been greeted and welcomed to the Province by Premier Manning who is also provincial Minister of Mines and Minerals, and to this City by Mayor Hawrelak. As Minister of Mines and Technical Surveys in the federal government and as Member of Parliament for Edmonton West, I have been asked to share the honour of extending greetings and a cordial welcome to all.It is a happy coincidence that this representative national gathering, indicative of the growing strength and significance of a great basic Canadian industry, is taking place in the Macdonald Hotel, the new addition of which marks another important step forward in the progress of this City and district.This happens to be the third national convention of the C.I.M. that I •have had the pleasure of attending and I trust that I am not presumptuous in expressing the hope that I will have the opportunity of attending many more conventions of the Institute in my present capacity.Dr. Kidd has bestowed on me a high honour by asking me to be Co-Chairman of this Inaugural Session of the Convention and thus to share with him the responsibility of presiding over the proceedings of this afternoon."

Jan 1, 1953

By S. Y. Tshipeng, A. T. Kaniki

"RÉSUMÉ La lixiviation acide d’un minerai oxydé cupro-cobaltifère en milieu non réducteur et en milieu réducteur en utilisant le Fe2+ et le métabisulfite de sodium (SMBS) a été étudiée et les résultats ont été comparés. Les tests de lixiviation ont été effectués à température ambiante, dans une pulpe à 30 % solide, avec une vitesse d’agitation de 600 tr/min, un potentiel redox de 350 mV pour les tests en milieu réducteur, et un pH de 1,8. Les tests de lixiviation avec usage du SMBS comme réducteur ont donné la meilleure cinétique de lixiviation du cuivre. Pour le cobalt, c’est l’usage du Fe2+ qui a donné la meilleure cinétique de lixiviation. L’augmentation de la dose du fer dans la solution au-delà de 5 g/L a influencé négativement les rendements de lixiviation du cuivre et du cobalt. ABSTRACT Acid leaching of a copper-cobaltiferous oxide ore in a non-reducing environment and in a reducing environment using Fe2+ and sodium metabisulfite (SMBS) was studied and the results compa¬red. The leaching tests were performed at room temperature, in a 30% solids pulp, with a shaking speed of 600 rpm, a redox potential of 350 mV for the tests performed in the reducing environment, and a pH of 1.8. The leaching tests using the SMBS as a reducing agent produced the best copper leaching kinetics. As for cobalt, the best leaching kinetics was achieved using Fe2+. An increase in the amount of iron in the solution above 5 g/L negatively influenced copper and cobalt leaching yields. INTRODUCTION La République Démocratique du Congo (RDC) est un pays reconnu dans le monde pour son sous-sol qui regorge d’énormes quantités de cuivre et de cobalt (USGS, 2014; Palisade Research, 2016). La technique qui semble être la plus recommandée pour extraire à la fois le cuivre et le cobalt des minerais oxydés cupro-cobaltifères est la lixivia-tion acide en milieu réducteur. Cette technique est appliquée par la majorité des sociétés minières qui exploitent ces minerais dans l’ex-province du Katanga en RDC, à savoir: Tenke Fungurume Mining, Mutanda Mining, Kamoto Cop¬per Company, Sicomines, Gécamines, Boss Mining, Chemaf, Ruashi Mining et Somika. L’usage d’un agent réducteur est indispensable pour l’obtention d’un bon rendement de lixiviation du cobalt. En effet, plusieurs chercheurs s’accordent sur le fait que le cobalt trivalent de l’hétérogénite (CoO·2Co2O3·6H2O) est insoluble à l’action de l’acide seul; il ne devient soluble qu’après réduction en cobalt bivalent (Mwema, Mpoyo, & Kafumbila, 2002; Mulaba-Bafubiandi, Ndalamo, & Mamba, 2007; Ferron, 2008; Seo, Choi, Kim, & Tran, 2013; Stuurnam, Ndlovu, & Sibanda, 2014)."

Jan 1, 2018

By A. H. Mumin, A. Prikhodko

"This paper provides an understanding of interpreting and evaluating airborne time domain electromagnetic (TEM) surveys as applied to massive sulfide exploration. Variations in the conductive morphologies of massive sulfide ore systems are discussed, followed by forward modelling exercises examining the derived TEM response to these morphologies and discussion of the subtleties of data interpretation. Deposit morphology in the orientation at formation and the variations occurring due to later deformation are considered. Images of corresponding resistivity–depth models are provided. The combined modelling results provide a low-cost method for initial interpretation and screening of TEM anomalies. RÉSUMÉ Cet article nous permet de mieux comprendre l’interprétation et l’évaluation des levés élec-tromagnétiques aéroportés en domaine temporel (TDEM, de l’anglais time-domain electromagnetic) appliqués à l’exploration du sulfure massif. Y sont débattues les variations au niveau des morphologies conductrices des systèmes de minéralisation du sulfure massif, suivies d’exercices de modélisation prospective qui examinent la réponse dérivée des TDEM à ces morphologies et d’une discussion sur les subtilités de l’interprétation des données. L’étude envisage la morphologie de l’orientation originelle non déformée des gisements ainsi que les variations résultant d’une déformation ultérieure. Des images des modèles correspondants de résistivité-profondeur sont fournies. Les résultats combinés relatifs à la modélisation proposent une méthode peu onéreuse d’interprétation et de contrôle initiaux des anomalies dans les TDEM.INTRODUCTION Electromagnetic geophysical surveys are an indispensable foundation of many mineral exploration programs and can account for as much as half of the predrilling exploration costs. Quantitative mass interpretation of the survey results remains difficult due to the infinite variation of deposit morphologies, their complex physical properties, and the presence of barren conductive materials that can mimic or mask the response of targeted ore. Many modern geophysical investigations that focus on time domain electromagnetic (TEM) data interpretations are devoted to problems with inversion and modelling and their algorithms. Although a few of these investigations have resulted in commercial software products, these require highly qualified and experienced users and usually include geometric assumptions. Furthermore, without the input of known physical properties and geometric constraints, the inversion results are highly ambiguous. A number of case studies document the geophysical responses to known targets in well-defined and diverse geo-electrical environments, providing a high degree of correlation between field obser-vation and the results of the modelling used in this style of investigation (Hone, 1980; Schneider & Emerson, 1980; Tyne, Idnurm, & Malone, 1981; Bishop & Lewis, 1992; Hopgood & Hungerford, 1994; Meju, 2002; Yang & Oldenburg, 2016). The uniqueness of the target/environment parameters and their specific features limits the use logy is poorly understood. The responses are therefore that are devoid of complicating environmental factors (e.g., highly conductive overburden and hostrocks or nonuniform target conductivity) as a first approach to the interpretation process of such case studies as the main reference for interpreting TEM survey responses in areas where the underlying geomodelled from generalized and typical geological models"

Jan 1, 2018

By P. Mottahed, E. De Souza

One of the major unsolved problems of safe, economical roof support in the evaporite industry has been that of obtaining and maintaining anchorages in relatively soft rock. This is due to the viscoelastic and viscoplastic behaviour of salt rock and associated deposits. This paper introduces a low-cost, yieldable support mechanism, consisting of a system of buckling disks, which provides viable solutions to dynamic support. The yieldable support system offers a number of advantages in comparison with existing dynamic support systems. It is characterized by its simplicity in design and installation, repeatability in behaviour and cost effectiveness. It also has the added advantage of providing the operator with a means of assessing support behaviour and ground performance by direct visual observation of changes in disk shape. Thus, the system can be utilized as a warning mechanism of ground stress and support load conditions. Such system not only provides a feasible and more effective rock mass stabilization strategy but improves mine safety.

Jan 1, 1999

By Pizhi Zhao, Jingwei Zhao, Zhenshan Liu, Yiheng Cao

"A new Al-Mg-Si-Zn alloy designed for automotive outer panel was trial-produced with industrial procedure. The final product shows a strong planar anisotropy. X ray diffraction analysis shows such strong anisotropy is caused by the dominating cube texture component in the final product. The reason for such high cube texture component was investigated by tracing texture evolution starting from the hot roll slab. It is found that certain cube texture components already exists in the hot rolled slab. The density of cube texture component shows as a wavy change through the following1st cold rolling, inter-annealing, 2ndcold rolling and solution treatment. This study shows that the cold rolling in the laboratory can well represent the texture evolution during the industrial production. The results obtained by lab rolling hints that change of second cold rolling reduction has weak effect on the planar anisotropy, when the gauge of hot rolled slab and final sheet are fixed.INTRODUCTIONWith the rapid progress of light-weighting in the automotive industry, aluminum sheets get more and more application as closure panel and structure parts. Recently the dominating alloy for outer panel is 6xxx series, containing the main alloy elements Mg and Si. The popular gradesareAA6016,AA6111, AA6022, and AA6014. These alloys still cannot satisfy the various requirements from automotive manufacturers. Most suppliers of automotive aluminum sheets are developing their own specific grades according to the customer’s demand. To increase the baking response, anew Al-Mg-Si-Zn alloy was designed, concerning the high combination energy between Zn solutes and vacancies formed during the quenching stage of automotive sheet manufacture. This combination is helpful to the precipitation of ß”phase during the paint baking (Wang, 2015,2016; Yan, 2014).The plastic strain ratio (r value)is a key index of the formability of automotive body sheet. A high r value means a good formability. The r values in different directions can be used to evaluate the planar anisotropy of the metal sheets. The trial produced Al-Mg-Si-Zn sheet shows a strong planar anisotropy with respect to r values. Since the r value is tightly related with texture, the texture evolution from hot roll slab (HRS) to final T4P temper was analyzed with X ray diffraction (XRD) to find the reason for the high anisotropy. Besides, the cold rolling reduction (CRR) was varied in the laboratory to modify the texture distribution, i.e., the planar anisotropy."

Jan 1, 2018

By James G. Lyons

All machines vibrate and make noise. An increase signals impending trouble. Vibration and noise analysis allows the condition of the machine to be determined without costly interruption in service for disassembly and physical inspection.

Jan 1, 1977

By Mark Rebagliati, John Payne, Jim Oliver

Abstract-The Campo Morado precious-metal-bearing, volcanogenic massive sulfide deposits occur in a lower Cretaceous, bimodal, calc-alkaline volcanic sequence in a major northerly trending belt in the Guerrero Terrane in northeastern Guerrero, Mexico. During upper Cretaceous to Early Tertiary greenschist-facies regional metamorphism, the rocks were deformed strongly into a northeast-verging fold-and-thrust belt. Three later stages of weak deformation were dominated, respectively, by kink folds, broad warps, and extensional faults. Most deposits occur in the upper part of a sequence of felsic flows and heterolithic volcanoclastic rocks or at its contact with overlying chert and argillite-sandstone. The Reforma and El Rey massive sulfide deposits are on the overturned limb of a major, thrusted anticline, and the Naranjo and El Largo massive sulfide deposits are to the south on the upright limb of the same major fold. The La Lucha and San Rafael massive sulfide occurrences are in an upper plate to the southwest which was thrusted over the plate containing the Naranjo and El Largo deposits. In several of the deposits, Au, Ag, Zn, and Pb are concentrated near the stratigraphic top, and Cu is concentrated near the stratigraphic base. Major minerals are pyrite, quartz, ankerite, sphalerite, chalcopyrite, and galena. Minor minerals are tennantite-freibergite, arsenopyrite, and pyrrhotite. Gold and Ag occur in argentian gold, and Ag also occurs in tennantite-freibergite. The cumulative inferred resource of massive sulfide for the Reforma, Naranjo, El Rey, and El Largo deposits exceeds 30 Mt, with the latter two deposits incompletely delineated. Underlying pyrite-quartz stockwork zones contain chalcopyrite, chlorite, and sphalerite. Hydrothermal alteration minerals in the stratigraphic footwall are pyrite, quartz, chlorite, ferroan dolomite, and ankerite. In the stratigraphic hangingwall, hydrothermal alteration minerals are sericite, calcite-dolomite, and lesser clay minerals and quartz. The deposits belong to a low-sulfidation, volcanogenic massive sulfide system formed in a subaqueous environment, and are of the bimodal, siliciclastic type.

Jan 1, 1997

By Tao Long

Recently, the great amount of funds has been invested in the reconstruction of damaged infrastructure and house of subsidence area of coal mine and mine reclamation. This is a benevolent and popular work, which is highly praised. However, because of complicated collapse area problems in China, especially the less integrated control research in the collapse area of metal mine, and the technological weakness, how to effectively control the subsidence area, restore landscape and ecological environment, and utilize the abandoned mine land, are major issue related to the mining area of sustainable development. The research situation about the formation of metal mine collapse area at home and abroad is reviewed, and then the effect of the collapse area on the mine safety and ecological environment, the existing technical problems and development direction are analyzed. Lastly, the technical measures of the collapse area control and cooperative underground mining is put forward.

Oct 1, 2010

By John C. Taylor

A resource document, prepared for the Royal Commission on the Health and Safety of Workers in Mines, which outlines aspects of occupational health and safety in the Canadian metallurgical industry has been expanded to provide examples of some practical solutions. General process descriptions are provided in conjunction with some of the major potential hazards associated with each step. Emissions to the working environment, particularly around converters, are discussed. Newer metallurgical processes, the role of automation and other advances in the metallurgical industry are described with respect to their impact on the work place. The role of staff and unit employees in providing safe working conditions in the complex metallurgical plant of today is outlined and the need for close cooperation within the human sector emphasized. The technology is available and is being applied to integrate the complex process requirements with realistic regulations to control emissions and provide a safe, healthy environment in metallurgical plants.

Jan 1, 1978

By R. Pelton, Z. Dai, S. Yang

ABSTRACT Hydrophobic polystyrene nanoparticles were evaluated as potential flotation collectors for pentlandite. The flotation of hydrophilic glass beads demonstrated the nanoparticles’ ability to induce flotation. Deposition of nanoparticles on glass surfaces increased the contact angle and enhanced adhesion of the beads to air bubbles. High flotation recoveries were achieved when 5–10% of the bead surfaces were covered with nanoparticles. Surface functionalization—the addition of vinylimidazole to polystyrene nanoparticle surfaces—caused the nanoparticles to selectively deposit onto pentlandite surfaces in the presence of Mg-Si slimes. Ongoing work includes attempts to identify specific applications where nanoparticle collectors might be cost effective. _ KEYWORDS Flotation, Nanoparticle collector, Coverage

Jan 1, 2014

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

By Derek V. Ellis

Coastal and marine mines affect the seabed?s biological resources, eg fisheries, when large volume wastes such as tailings are placed on the seabed, and by the extraction processes from marine mining. Worldwide monitoring of such effects for the past 30+ years now provides information to describe Best Practice design, construction and monitoring procedures. The critical environmental factors for submarine tailings placement (STP) are the selection of an appropriate deposition site and discharge depth, the deposition rate of the tailings, and the speed of biodiversity recovery to a sustainable ecological succession. These should be predictable at new sites using current modeling and experimental procedures. Prediction procedures are still needed to minimize potential destabilization of deposited tailings, and consequent biodiversity recovery setbacks. Comparable environmental information is needed from marine mining sites.

May 1, 2002

By D. Hodouin

Jan 1, 1978

By D. Duff, R. A. Cameron, R. E. S. Whitehead

"Although CO2 content indicates the quantity of carbonate in altered basaltic rocks, it does not measure the intensity of carbonate alteration. CO/CaO molar ratios, which correlate with the relative proportions of individual carbonate species, measure the intensity of carbonatization. The Timmins gold area is characterized by pervasive carbonatization, with large parts of the area having CO2/Ca0 ratios greater than 1, representing C02 supersaturation relative to CaO. The mean CO/CaO in the Timmins area is0.67, compared to 0.13 in two unmineralized control areas. Regional arsenic abundance in the gold-bearing area averages 4 ppm, compared to about 0.35 ppm for the non-mineralized areas. The average K20 and Rb abundances are similar in both mineralized and non-mineralized areas (about 0.30% K20 and 7 ppm Rb). Although there appears to have been no wholesale addition of K20 or Rb to the mineralized area from external sources, these alkalies have been redistributed internally, resulting in patterns of local enrichments and depletions which are characteristic of the mineralized region.Local target anomalies associated with known mineralization consist of CO2/Ca0 > 1.5, As > 10 ppm and K2O > 0. 75%. Not all three values are required to be above these thresholds in order to identify local targets. Combinations such as C02/ Ca0 > 1.5 and As < 10 ppm, CO/CaO 1-1.5 and K20 > 0. 75 or K20 > 0. 75 and As > 10 ppm are equally indicative of proximity to gold occurrences. Gold-bearing veins and associated anomalies occur throughout the entire volcanic succession and are not restricted to any particular stratigraphic horizons. The levels and patterns of alteration and occurrences of gold appear to be structurally controlled."

Jan 1, 1982