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Geology · 400 Level
This is the complete lecture note for GEY 404 Economic Geology, prepared for Geology students at 400 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS GEY 404: Economic Geology (3 Units C: LH 30; PH 45) Course Code: GEY 404 Course Title: Economic Geology Course Unit: 3 Units C Series 1: Fundamentals Of Economic Minerals And Deposits Series 2: Geological Characteristics And Classification Of Ore Deposits Series 3: Principles And Processes Of Mineral Deposit Formation Series 4: Prospecting, Exploration, And Mine Development Series 5: Ore Reserve Calculation And Mineral Economics Series 1 Fundamentals Of Economic Minerals And Deposits • Part 1.1 Definition Of Economic Minerals And Deposits • 1.1.1 Economic minerals • 1.1.2 Economic mineral deposits • Part 1.2 Ore And Gangue Minerals • 1.2.1 Characteristics of ore minerals • 1.2.2 Characteristics of gangue minerals • Part 1.3 Tenor And Cut-Off Grade • 1.3.1 Tenor of ore deposits • 1.3.2 Cut-off grade and its significance • Part 1.4 Importance Of Economic Geology • 1.4.1 Role in resource development • 1.4.2 Applications in industry and society Introduction Minerals are essential to modern life, forming the backbone of industries ranging from construction and manufacturing to energy and technology. Yet, not all minerals are considered economically valuable. This Series introduces you to the fundamentals of economic minerals and deposits, laying the foundation for the rest of the course. By understanding what makes a mineral
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS deposit economically viable, you will be better prepared to explore how these resources are classified, formed, and utilised. The aim of this Series is to help you define economic minerals and deposits, distinguish between ore and gangue minerals, explain the concepts of tenor and cut-off grade, and appreciate the importance of economic geology in resource development and society. We shall commence this Series by examining the definition of economic minerals and deposits. Next, we will explore ore and gangue minerals, highlighting their contrasting roles in mining. Following that, we will discuss tenor and cut-off grade, which are critical in determining whether a deposit can be mined profitably. Finally, we will wrap up by considering the broader importance of economic geology in industry and society. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define economic minerals and economic mineral deposits, • SLO 1.2 distinguish between ore minerals and gangue minerals, • SLO 1.3 explain the concepts of tenor and cut-off grade in evaluating deposits, and • SLO 1.4 evaluate the importance of economic geology in resource development and industry. 1.1 Definition Of Economic Minerals And Deposits 1.1.1 Economic minerals Economic minerals are naturally occurring substances that are extracted and used profitably in industry, trade, or everyday life. Their value lies not only in their physical presence but also in their utility and demand. Examples include metallic minerals such as gold, copper, and iron, as well as non-metallic minerals like limestone, gypsum, and phosphate. The distinction between economic and non-economic minerals is based on whether extraction and processing can be carried out at a profit. A mineral may be abundant, but if it cannot be mined economically, it is not considered an economic mineral.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.1 Examples of economic minerals Fill in the blank: A mineral is considered economic if it can be mined ______. 1.1.2 Economic mineral deposits An economic mineral deposit is a concentration of minerals in the Earth’s crust that can be extracted profitably. Deposits vary in size, grade, and accessibility, and these factors determine whether they are viable for mining. For example, a gold deposit with high grade and easy accessibility is more likely to be mined than a low-grade deposit in a remote location. Economic mineral deposits are classified into different types based on their geological characteristics, such as stratiform deposits (layered within sedimentary rocks) or vein deposits (formed in fractures). These classifications are important because they guide exploration strategies and mining methods. Box 1.2 Types of economic mineral deposits Deposit Type Geometry Continuity Typical Host Rock Stratiform Tabular/Layered High (Horizontal) Sedimentary / Volcanic
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Deposit Type Geometry Continuity Typical Host Rock Vein Sheet-like High (Linear/Vertical) Any (Fractured) Pipe Cylindrical High (Vertical) Volcanic / Intrusive Stockwork Network/Massive High (Volumetric) Igneous (Porphyries) Fill in the blank: A mineral deposit is considered economic if it can be extracted ______. Pilot questions 1.1 1. What are economic minerals? 2. Give two examples of metallic economic minerals. 3. What determines whether a mineral is considered economic? 4. Define an economic mineral deposit. 5. Name two types of economic mineral deposits. 1.2 Ore And Gangue Minerals 1.2.1 Characteristics of ore minerals Ore minerals are naturally occurring minerals from which metals or other valuable elements can be profitably extracted. They are the primary source of metals such as copper, lead, zinc, and gold. Ore minerals are distinguished by their high concentration of valuable components, which makes them economically viable for mining. For example, chalcopyrite is an ore mineral of copper, while galena is an ore mineral of lead. The presence of ore minerals in sufficient quantity and quality determines whether a deposit can be classified as an ore deposit.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.3 Common ore minerals Fill in the blank: Chalcopyrite is an ore mineral of ______. 1.2.2 Characteristics of gangue minerals Gangue minerals are the non-valuable minerals that occur alongside ore minerals in a deposit. They do not contribute economic value but must be separated during mineral processing. Common gangue minerals include quartz, calcite, and feldspar. Although gangue minerals are not economically valuable, they play an important role in determining the cost and complexity of ore processing. A deposit with a high proportion of gangue minerals may require more intensive beneficiation techniques, which can affect profitability. Box 1.4 Examples of gangue minerals Mineral Chemical Formula Typical Ore Association Hardness (Mohs) Processing Challenge Quartz $SiO_2$ Gold veins, Porphyry copper 7 High Abrasiveness: Increases wear on
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Mineral Chemical Formula Typical Ore Association Hardness (Mohs) Processing Challenge crushers and grinding balls. Calcite $CaCO_3$ Lead-Zinc (MVT), Skarns 3 Acid Consumption: Neutralizes acid in leaching, increasing chemical costs. Feldspar $KAlSi_3O_8$ Pegmatites, Granitic hosts 6 Slime Formation: Can weather into clays that interfere with flotation. Pyrite $FeS_2$ Copper, Gold, Volcanogenic Sulfides 6–6.5 Environmental Risk: Primary source of Acid Mine Drainage (AMD). Dolomite $CaMg(CO_3)_2$ Sedimentary-hosted Base Metals 3.5–4 Chemical Interference: Similar to calcite; complicates carbonate separation. Kaolinite $Al_2Si_2O_5(OH)_4$ Oxidized/Supergene zones 2–2.5 Viscosity Issues: Increases pulp thickness, making pumping difficult. Fill in the blank: Quartz is a common example of a ______ mineral. Pilot questions 1.2 1. What are ore minerals? 2. Give two examples of ore minerals. 3. What determines whether a mineral is classified as an ore mineral? 4. Define gangue minerals.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 5. Name two common gangue minerals. 1.3 Tenor And Cut-Off Grade 1.3.1 Tenor of ore deposits Tenor refers to the average content of valuable metal or mineral within an ore deposit. It is usually expressed as a percentage or in grams per tonne, depending on the type of mineral. Tenor is a critical factor in determining whether a deposit can be mined profitably, since higher tenor generally means more valuable material per unit of ore. For example, a gold deposit with a tenor of 10 grams per tonne is considered richer than one with 2 grams per tonne. However, tenor alone does not determine economic viability, as other factors such as accessibility and processing costs must also be considered. Figure 1.5 Tenor of ore deposits Fill in the blank: Tenor refers to the average ______ of valuable mineral in an ore deposit. 1.3.2 Cut-off grade and its significance Cut-off grade is the minimum grade of ore that must be mined and processed for the operation to remain economically viable. Ore below the cut-off grade is considered waste, while ore above it is treated as valuable. Cut-off grade is influenced by factors such as market prices, mining costs, and processing efficiency.
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