Metallogenesis-Ore Minerals

The course has two main goals. The first one is the acquisition of basic knowledge of the geological, mineralogical and geochemical features of the numerous mineral deposits, rich in critical metals and minerals, which can form via hydrothermal processes. The second goal is to provide the ability to identify assemblages of metallic (sulfides, sulfosalts, oxides and alloys) and gangue minerals by reflected light/metallographic microscopy and by observation of hand specimens from the main types of mineral deposits. This activity will focus on economic minerals, also known as "ore minerals" and, in particular, those involved in the list of the so-called Critical Raw Materials (CRMs). It will be possible to verify how the optical characters of minerals and their microtextures (possibly paired with additional analytical facilities) may provide preliminary, yet significant indications about conditions of deposition of mineralization, or even be useful for further evaluating either the economic value of an orebody and/or the consequences of a bad management of mining waste.

At the same time the students will learn how to identify the accessory "opaque" minerals hosted in common rocks. Opaque minerals are often sensitive to chemical-physical conditions in magmatic or metamorphic processes or may suggest the sources of rock components. Moreover, opaque minerals can be true "ore minerals" (e.g., Ti oxides, nowadays listed as CRM) or else be cause of damage in commercial ornamental stones (e.g., fine-grained accessory pyrite in stone slabs for outdoor paving).

At the end of the course the student should be able to:

(a) possess some knowledge about the mechanisms of formation for the main types of hydrothermal ore deposits and about the methods for investigating them. Such knowledge may be useful either for further research on ore deposit modeling or for a possible work in a mining company involved in mineral prospecting;

(b) identify, by means of reflected light microscopy, numerous metallic minerals of economic value for industry and associated precious metals (Au, Ag, PGE) and gangue minerals;

(c) recognize the mineral assemblages and micro-textures typical for the main types of mineral deposits formed in a wide range of geological conditions, from high to low temperature and in deep, magmatic to suficial-marine-exhalative/diagenetic contexts;

(d) derive useful information about the chemical-physical conditions of ore deposition from the optical and microtextural features of ore and gangue minerals;

(e) have a basic knowledge for contributing to the mineralogical and chemical characterization of the different portions of an orebody towards a rational planning of its mining exploitation and, last but not least, of the management of related toxic mining waste;

(f) rapid identification of the accessory opaque minerals in common rocks often useful to better understand the "history" of their host rocks or else to better evaluate an adequate employment of commercial ornamental stones.