Half Zantop

NATURAL AMMONIUM ILLITES FROM BLACK SHALES HOSTING A STRATIFORM BASE METAL DEPOSIT, DELONG MOUNTAINS, NORTHERN ALASKA

Naturally occurring ammonium illites have been discovered in black shales surrounding a stratiform base metal deposit in the DeLong Mountains, northern Alaska. Infrared spectra of the samples exhibit pronounced absorption at 1430 cm−1, the resonant-banding frequency for NH4+ coordinated in the illite interlayer. X-ray powder diffraction characteristics of the ammonium illites include an expanded d(001) spacing, with values as large as 10.16 Å, and ratios for I001/I003 and I002/I005 of about 2. Infrared analyses of physical mixtures of NH4Cl with a standard illite, and comparisons with synthetic ammonium micas indicate significant substitution (>50%) of NH4+ for K+ in the illite interlayer position. Nitrogen determinations on two ammonium illites after removal of carbonaceous matter gave values of 1.48 wt. % NH4+ and 1.44 wt. % NH4+. A survey of more than 150 different shale horizons indicates that the NH4+ content of the illites increases in proximity to the stratiform base metal mineralization.РезюмеНатурально выступающие аммониевые иллиты были открыты в черных сланцеватых глинах, окружающих основной металлический осадок в горах ДеЛонга в северной Аласке. Инфракрасные спектры образцов указывают на значительную абсорбцию при 1430 см−1, частоте резонансной полосы NH4+, координированного в иллитовой прослойке. Характеристики рентгеновской порошковой дифракции аммониевых иллитов включают увеличенное расстояние d(001), co значениями, достигающими 10,16 Å а также отношениями I001/I003 и I002/I005 порядка 2. Инфракрасные анализы физических смесей NH4Cl со стандартным иллитом и сравнения с синтетическими аммониевыми слюдами указывают на значительную подстановку (>50%) иона NH4+ вместо иона K+ в межслойной области иллита. Определение количества азота в двух аммониевых иллитах после удаления углистой среды привело к величинам 1,48% веса NH4+ и 1,44% веса NH4+. Исследование более, чем 150 различных ярусов сланцевых глин показывает, что количество NH4+ в иллитах увеличивается в поблизости основной металлической минерализации. [E.C.]ResümeeNatürlich auftretende Ammonium-Illite wurden in den Schwarzschiefern gefunden, die eine schichtförmige Erzlagerstätte in den Delong Mountains, Nord Alaska, umgeben. Die Infrarotspektren der Proben zeigen eine deutliche Absorption bei 1430 cm−1, d.h. die Resonanzfrequenz von NH4+, das in die Illitzwischenschicht eingebaut ist. Die Röntgenpulverdiffraktometerdiagramme der Ammonium-Illite zeigen einen aufgeweiteten d(001) Abstand, mit Werten um 10,16 Å und I001/I003 bzw. I002/I005 Verhältnissen von etwa 2. Infrarotuntersuchungen an mechanischen Gemengen aus NH4Cl und einem Standard Illit und Vergleiche mit synthetischen Ammonium-Glimmern deuten auf eine beträchtliche Substitution (>50%) von NH4+ für K+ auf den Zwischenschichtplätzen des Illit hin. Stickstoffbestimmungen an zwei Ammonium-Illiten nach der Entfernung von kohlenstoffhaltigen Substanzen ergaben Werte von 1,48 Gew.-% NH4+ bzw. 1,44 Gew.-% NH4+. Untersuchungen von mehr als 150 verschiedenen Schieferhorizonten deuten darauf hin, daß der NH4+-Gehalt der Illite mit zunehmender Nähe an die Metall-Mineralisation ansteigt. [U.W.]RésuméDes illites ammonium de provenance naturelle ont été découvertes dans des argilites noires entourant un dépôt stratiforme d’un métal de base dans les montagnes DeLong en Alaska du nord. Des spectres infrarouges des échantillons exhibent une adsorption prononcée à 1430 cm−1, la fréquence des liaisons resonantes pour NH4+ coordonné dans l’intercouche de l’illite. Les caractéristiques de diffraction poudrée aux rayons-X des illites ammonium comprennent un espacement d(001) élargi, avec des valeurs atteignant 10,16 Å, et des proportions pour I001/I003 et I002/I005 d’à peu près 2. Des analyses infrarouges de mélanges physiques de NH4Cl avec une illite standard, et des comparaisons avec des micas ammonium synthétiques indiquent une substitution significative (>50%) de NH4+ pour K+ dans la position intercouche illite. Des déterminations nitrogène sur deux illites ammonium après l’enlèvement de matière carbonacée ont donné des valeurs de 1,48 wt. % NH4+ et 1,44 wt. % NH4+. Un relevé de plus de 150 horizons argilite différents a indiqué que le contenu en NH4+ des illites accroit à proximité de la minéralisation stratiforme du métal de base.

International mineral economics

This book provides an integrated overview of the concepts important for mineral exploration, mine valuation, mineral market analysis, and international mineral policies. The treatment is interdisciplinary, drawing on the fields of economics, geology, business, and mining engineering. Part I, Economic Geology and Mineral Development, examines the technical concepts important for understanding the geology of ore deposits, the methods of exploration and deposit evaluation, and the activities of mining and mineral processing. Part II, Mineral Economics, focuses on the economic and related concepts important for understanding mineral development, the evaluation of exploration and mining projects, and mineral markets and market models. Finally, Part III, International Mineral Policies, reviews and traces the historical development of the policies of international organizations, the industrialized countries, and the developing countries.

The Economic, Institutional, and Legal Framework for Mineral Development

This chapter discusses important economic, institutional, and legal aspects of mineral development, broadly defined to include exploration as well as actual deposit development. It begins by considering mineral development as an economic activity, and then discusses the roles that various types of people and organizations play in mineral development. The chapter concludes by reviewing important aspects of mining legislation.

Mining and Mineral Processing

Successful exploration leads to the development of a mine for extraction of the ore and of a processing facility to transform the ore into a marketable product. The evolution toward this stage, and some of the costs involved in developing a mine, are discussed in Chapter 2 and illustrated in Figures 2.1, 2.2, and 2.3.

Quantitative Assessment of Mineral Potential

Previous sections have dealt with regional reconnaissance exploration and the identification of mineral targets by geologic, geophysical, and geochemical follow-up surveys. We now turn to the next step in the search of an ore deposit: the search for the source of an anomaly, and, if it is an ore body, the determination of its ore grade and tonnage by systematic sampling. This type of assessment may also take place, without prior regional exploration, in areas of known mining or exploration history which become attractive because of rising commodity prices, cost reductions in mining and processing, improvements in recovery by more effective processing technology, or the recognition of new geologic models which warrant renewed exploration. This quantitative stage of exploration represents a transition from the investigation of secondary and primary dispersion halos to ore; from indirect exploration to direct target definition; from relatively low cost to high cost in absolute terms and per unit area; and from the geologic domain of exploration and grade-tonnage assessment to the engineering and economic domains of mining, mineral processing, financial evaluation, and marketing studies. Because of the large expenses involved in these evaluations without assurance that a project will be profitable, this is the highest-risk stage of geologic exploration and the stage at which vigorous management support is most needed. Exclusive exploration and exploitation rights are secured to protect the investment, and access and land use is negotiated with surface owners.

Policies in Industrialized Countries

Most European industrialized countries and Japan depend on substantial imports of minerals. Owing to this, the supply aspect of mineral policy has in recent years been given such emphasis that the term mineral supply policy has emerged.

Policies and Cooperation Programs of International Organizations

Mineral policies significantly influence the environment in which mineral production occurs, the level of distribution of international mineral trade, and the optimum use of scarce mineral resources.

Policies and Special Problems in Developing Countries

In recent years, developing countries rich in mineral resources have clearly formulated their joint mineral policy goals at an international level (see Sect. 8.1.1). The major concern of each of these countries is to gain greater control over the exploitation of its natural resources and to derive maximum benefit from them. This is understandable: for many developing countries control is vital because these raw materials are indispensable as a basis for economic development. These countries depend at the same time on the assistance of the industrialized nations for the know-how and capital needed to prospect for and open up deposits. The maintenance of this assistance must thus constitute one of the goals of commodity policy in developing countries. These two goals are difficult to reconcile with one another; the conflict can only be resolved by means of a compromise. Attempts to arrive at such a compromise are evident in national mining legislation, which contains very disparate features.

Economic Evaluation of Mineral Deposits

Economic geology and mineral economics encompass a variety of activities. One important aspect of these disciplines is the identification and evaluation of mineral deposits. Part of this work is largely technical in nature. Explorationists, for example, use the tools of geology, geochemistry, geophysics, and other fields to identify mineral deposits. They then study the deposits to determine if they exhibit the physical and chemical characteristics typical of similar deposits that have been developed into mines; and, in the case of a new type of deposit, to draw inferences on the basis of new scientific knowledge. Other parts of this work, however, are largely economic in nature. Economists, engineers, and others work together to evaluate a mineral deposit’s economic potential by comparing the expected revenues from mine production with the associated expected costs of further exploration, development, and production. It is their task to determine if the expected revenues from developing a deposit will be sufficiently in excess of costs to provide investors with an adequate return on their investment. Still other parts of the work may be socio-economic in nature, if a government is involved; the concern here is how the development of a deposit will affect the overall economic and social development of a region or country.

Mineral Deposits and Metallogenic Concepts

A geologist defines a mineral as a naturally occurring, crystalline solid of specific chemical composition, structural arrangement of component atoms, and physical properties, e.g., quartz, pyrite, diamond. Minerals combine to form rocks, defined as naturally occurring accumulations or mixtures of minerals formed by geologic processes, e.g., granite, limestone, oil shale. In the context of mineral economics, the term “mineral resources” is commonly used to denote all solid, liquid, or gaseous geologic materials exploitable for use.