Minerals and rocks

The objective of this course is to introduce the concepts and tools used to observe and describe igneous and metamorphic rocks, understand their genesis, and appreciate their importance in the geosciences.

The lessons will begin with an introduction to the concepts of mineralogy (crystallography, crystal chemistry) and the tools needed to identify the minerals that make up igneous and metamorphic rocks, both on a macroscopic and microscopic scale.

The different types of igneous and metamorphic rocks will then be presented and placed in the geodynamic contexts in which they were formed.

Two field trips in the Montpellier region will be offered to illustrate and supplement the lessons: the first trip will focus on volcanism in the Hérault Valley (from Agde to Salagou), while the second will cover magmatic and metamorphic areas in the Cévennes.

Know how to identify the main minerals in igneous and metamorphic rocks, understand the conditions under which they form, identify the main igneous and metamorphic rocks, and understand the conditions under which they are formed.

Basic knowledge of chemistry: periodic classification of elements and physical and chemical properties of chemical elements. Basic concepts of mineralogy and crystallography (definition of a mineral, what it is made of, properties that enable identification, recognition of common minerals).

Continuous assessment. Students will be assessed during the semester on three tests evaluating their practical and theoretical knowledge acquired in lectures, practical work, and in the field:

- a test on mineralogy, accounting for 40% of the final grade,

- a test on magmatism, accounting for 30% of the final grade

- a test on metamorphism, accounting for 30% of the final grade.

• Brief description of the concepts covered in CM:

CM1: Mineralogy. Concepts of crystal chemistry: how is a crystal formed? From the properties of elements to the formation of a silicate (Pauling's rules).

CM2: Mineralogy: Silicate classification. Presentation of the major silicate groups and focus on a few silicates illustrating the role of atomic-scale structure on physical and chemical properties.

CM3: Magmatic petrology: Classification of magmatic rocks, structure and nature of the mantle, processes of partial melting and fractional crystallization.

CM4: Magmatic petrology: physical properties of magmas, dynamics and eruptive styles, magmas in their geodynamic context.

CM5: Metamorphic Petrology

CM6: Metamorphic Petrology

• Brief description of practical sessions and number of hours associated with each session

TP1: Mineralogy. Review of the physical properties of minerals that enable their identification. Macroscopic recognition of silicates (quartz, micas, amphibole, pyroxenes, garnets, olivine, metamorphic silicates).

TP2: Macroscopic recognition of silicates. Work on the atomic structures of several silicates to illustrate the course (quartz, olivine, micas).

TP3: Introduction to the optical microscope: use in unanalyzed polarized light.

TP4: Introduction to the optical microscope: use in polarized light analyzed.

TP5: Macroscopic and microscopic identification of volcanic rocks.

TP6: Macroscopic and microscopic identification of plutonic rocks.

TP7: Macroscopic and microscopic identification of MP/MT metamorphic rocks.

TP8: Macroscopic and microscopic identification of HP/HT metamorphic rocks.

• Description of the topics/activities covered during your field trip(s) and details of the destinations/sites

Field trip 1: Volcanism in the lower Hérault valley: Baumes volcano, Lézignan-la-Cèbe lava flows, Cap d'Agde volcano, and Conque beach. The aim of this field trip is to illustrate the basaltic volcanism that prevailed during the Quaternary period in the lower Hérault valley. The aim is to highlight different styles of eruption (phreatomagmatism, Strombolian dynamism, lava flow structuring) through field observation of volcanic edifices at outcrops. It also aims to reflect on the origin of magmas through observation of rocks at outcrops.

Outing 2: Metamorphism in the Cévennes: Arres, Col de la Barrière, Dourbies.

During this field trip, the main focus will be on identifying metamorphic rocks and structures outcropping in the Cévennes (green schists, metamorphic dolomites, cordierite and andalusite schists) and reconstructing the history of the formation of these metamorphic rocks. A section of approximately 2 km will be surveyed between the Col de Rhodes and Dourbies in order to characterize the metamorphism associated with the formation of the Saint-Guiral-Liron granite pluton.

• Know how to recognize the main minerals in igneous and metamorphic rocks on a macroscopic scale.
• Understand the basic principle of how a polarizing optical microscope works and know how to use it to identify common minerals in polarized and polarized-analyzed light.
• Know how to identify the main types of igneous and metamorphic rocks and know how to associate them with geological contexts.
• Knowing how to read a geological map
• Knowing how to read a landscape and construct an outcrop drawing