Ore Petrography and Evvironmental Evaluation of ore Minerals

A.Y. 2021/2022
Overall hours
Learning objectives
The course is aimed to provide some in-depth knowledge about economically valuable metallic minerals (ore minerals) occurring in mineral deposits. The first, wide part of the course will teach students to use reflected light microscopy (metallographic technique) (a) for identifying metallic (sulfides, sulfosalts, oxides, alloys, etc.) and gangue minerals in assemblages typical for the main types of ore deposits; (b) for identifying the accessory "opaque" minerals in non-mineralized rocks; (c) for obtaining indications useful for constraining conditions of depositions of mineralization from optical and micro-textural features of the ore minerals. The second part of the course provides basic knowledge and technical and procedural skills about the following topics: (1) methods for evaluating the mineral liberation and the Separation Efficiency; (2) mineralogical and metallographic studies aimed to evaluate and improve the beneficiation processes; (3) the main environmental issues related to the exploitation of ore deposits rich in metallic minerals, with special reference to sulfide-bearing mineralization; (4) evaluation of environmental risks in active and dismissed mining sites.
Expected learning outcomes
At the end of the course the student should be able to:
- (a) use reflected-light microscopy for identifying numerous metallic minerals employed in industry and containing precious metals (Au, Ag, PGE) as well as associated gangue minerals; (b) recognize the ore mineral assemblages and the micro-textures of the main types of ore deposits; (c) contribute to the mineralogical and chemical characterization of the orebodies in their different portions towards a rational planning of mining exploitation; (d) identify the accessory opaque minerals in non-mineralized rocks and evaluate their sensitivity to chemical-physical conditions during magmatic and metamorphic processes.
- (1) evaluate, in a qualitative way, as well as perform quantitative procedures apt for determining the mineral liberation and the Separation Efficiency in enrichment plants; (2) perform a technical analysis of mining sites towards the evaluation of the environmental risks; (3) perform qualitative and quantitative procedures aimed to measure the parameters of the acid mine drainage and to evaluate the viability of the main methods for remediation and environmental restoration of polluted sites by applying the methods to specific sites and situations.
Course syllabus and organization

Single session

Lesson period
First semester
Course syllabus
The course is intended to outline some major topics related to the study of metallic minerals both when concentrated in ore deposits ("ore minerals") and as accessory phases in unmineralized rocks ("opaque" minerals). The course comprises two parts, a practical part in laboratory and a part with class lecturing (2 cfu, 16 hours - run by Prof. Giovanni Grieco)
The practical part in laboratory (4 cfu, 48 hours - run by Prof. Marilena Moroni for 3 CFU and by Prof. Giovanni Grieco for 1 CFU) is devoted to the study of opaque and ore minerals (from rocks and ore deposits) and their associations and microtextures by means of reflected light microscopy on polished sections.
The class lectures (2 cfu, 16 hours), held by Prof. Giovanni Grieco, outlines the fundamental topics about serious environmental problems derived both from specific ore mineral associations and from the modes of mining exploitation and processing of the ore minerals.
The practical part of the course is devoted to the identification and description of the most common and economically significant opaque and ore minerals, their textures and mutual relationships by means of metallographic, reflected-light microscopy. Practice is acquired by examining numerous high-quality polished sections from the main types of ore deposits inside and outside Italy. Mineral associations from the following deposit types are examined: (a) magmatic-hydrothermal and high-temperature hydrothermal deposits related to granitic magmatism (greisen, skarn, (Mo, W, Sn, Bi, Pb, Ag, Cu); mesothermal polymetallic veins, porphyry copper deposits); (b) metamorphic shear-zone hosted mesothermal polymetallic and gold vein deposits (Au, Ag, Cu, Pb, Zn, Bi, As); (c) epithermal deposits (Sb, Hg, Au, Ag); (d) volcanogenic and sedimentary-exhalative massive sulphide deposits and their metamorphosed and deformed equivalents (Cu, Fe, Pb, Zn, Ag); (e) deposits hosted in mafic-ultramafic magmatic rocks (Cr, Ni, Fe, PGE); (f) diagenetic deposits (Pb-Zn, U).
The topics of the class lectures are meant to outline the modes of alteration and transformation of the associations of ore minerals in response to exposure to weathering agents (percolating waters, air, etc.) in active and abandoned mining sites and plants (mining pits and galleries, processing plants, mining rock and tailing dumps) and the consequences on the environment. Attention will be especially devoted to the evaluation of processes like Acid Mine Drainage and to the technical and legal aspects related to this environmental problem
Prerequisites for admission
All the subject of the teaching "Giacimenti minerari e esplorazione" are prerequisites and will be considered known by students during the classes of the present teaching.
Teaching methods
4 laboratory CFU are dedicated mainly to the observation in reflected light of thin and polished sections of different kinds of mineralized rocks. A preliminary explanation of the typology of samples is followed by the direct autonomous observation at the microscope by the students, during which teacher moves around providing help and explanations. A small part of the laboratory time is used for an exercise in the chemical laboratory, concerning test of industrial or environmental evaluation of concentrates or mine wastes. 2CFU consist of dialogue frontal lessons on environmental subjects.
Teaching Resources
Lecture notes provided by teachers, scientific articles, atlases of minerals in reflected light (paper and web). The sections used during the classes are made available to the students during a microscopy review session.
Assessment methods and Criteria
The exam consists in two compulsory tests: a practical/written test and an oral test. The written test concerns the reflected light microscopy laboratory classes and concerns 3 CFU. The test lasts about 4 hours and consists in an autonomous exercise of microscopy description in reflected light of two polished sections of ores (individuation of metallic and non metallic phases, microtextures, types of useful metals in high concentration, genetic interpretation etc.).
The oral test covers the topics dealt with in the second part of the teaching and consists in a discussion about environmental issues related to ore deposits with a specific focus on abandoned mine lands.
The final result i a weighed average of the results form each of the tests.
Practicals: 48 hours
Lessons: 16 hours
Professor: Moroni Marilena