GEOL20250 Crystals to Sedimentary Rocks

Academic Year 2023/2024

This module introduces the common rock forming minerals and considers how mineralogy is used to interpret igneous and metamorphic rocks. The module also addresses the texture and mineralogy of sediment and sedimentary rocks, which together with sedimentary structures, allow reconstruction of past Earth surface environments. The module consists of lectures and practical classes, supported by online exercises and other online information as preparation for practical exercises.

The first half of the module introduces the petrological (polarizing) microscope as the principal tool for the description and identification of minerals. Practical classes cover plane polarized light and crossed polarized light techniques and their use for the description of common rock-forming minerals, and examples of how mineral textures and chemical composition can be used to understand rock-forming processes. Mineral hand specimens will also be examined and their properties compared to optical properties under the microscope. Lectures will outline the optical theory required to understand polarized light observations; introduce chemical concepts used to understand minerals including elements and ions, the Periodic Table, chemical bonding and partition coefficients; introduce concepts in crystallography and mineralogy including atomic structure, chemical substitution and solid solution, exsolution and polymorphism; outline how silicate minerals are classified; introduce the relationships between mineral atomic structure, chemical, optical and other physical properties; and show how mineral textures and mineral compositions can be used in petrology to work out how igneous and metamorphic rocks formed.

The second half of the module focusses on clastic and carbonate sediment and sedimentary rocks. Lectures and on-line assignments will address the texture and composition of sand and sand grains and consider how these are controlled by how sediment is generated, transported, deposited and buried. Sedimentary structures formed by a range of processes (flows of water, air, gravity) will be covered and their use in reconstructing original Earth surface environments illustrated. Formation of sedimentary structures will be linked to the physics of the fluids that transport and deposit sediment. The typical components of carbonate rocks (limestones), the main environments in which they form, and their post-depositional evolution, will also be considered. Practical classes will use the petrological microscope, hand specimens, tank experiments and field data to characterise sediment formed in a range of settings and to explore how past environments are reconstructed.

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Curricular information is subject to change

Learning Outcomes:

On completion of this module, students should be able to:
1) Describe and identify some common rock-forming minerals in hand specimen.
2) Use a petrological microscope to describe and identify minerals, interpret textures and perform optical tests.
3) Demonstrate in writing a knowledge of mineralogy and mineral chemistry and how they can be used to determine how rocks formed.
4) Characterise and interpret the texture and composition of clastic sediment and sedimentary rocks.
5) Use sedimentary structures to reconstruct sediment transport processes and environments of deposition, and to identify environmental change.
6) Identify the main components in limestones and relate these to the original depositional setting.

Indicative Module Content:

Lectures will be held once per week at 11 am on Tuesdays in G01, Science West.

Week 1: Minerals, crystals and polarised light.
Course outline; the nature of ordinary and plane polarized light; optical properties under the petrological microscope in plane polarized light and between crossed polars.

Week 2: Silicate minerals.
Silicate composition of crust and mantle; The SiO4 tetrahedron, silicate polymerization and silicate classification, with examples of each class; Goldschmidt's rules, chemical substitution and solid solution; examples of silicate solid solutions; relationships between silicate properties and silicate classification.

Week 3: Mineral stability and phase diagrams.
Controls on mineral stability and its depiction on phase diagrams; crystal-liquid binary diagrams (anorthite-diopside and plagioclase); eutectic points; the Lever Rule in binary diagrams; polymorphism and the Al2SiO5 polymorphs; alkali feldspar solvus diagram and perthite textures.

Week 4: Igneous rocks.
Crystallization from magmas, volcanic and plutonic, and sequence of crystal growth, with implications for mineralogy and texture of igneous rocks. Controls on element partitioning, fractional crystallization, sequence of crystal growth and Bowen’s reaction series.

Week 5: Metamorphic rocks.
Solid state recrystallization in different temperature and confining pressure environments and implication for the mineralogy and textures of metamorphic rocks.


Week 7: Sediment and sedimentary rocks
Types of Sediment and sedimentary rock. Principle depositional processes and environments. Sedimentary Basins. Sediment grain size and texture. Classification of clastic sediments and rocks.

Week 8: Sandstone composition
Sandstone components. Heavy minerals. Composition and sandstone classification. QFL-diagrams. Main controls on sandstone composition. Provenance, source areas and palaeoclimate.

Week 9: Sediment transport and structures under unidirectional flow.
Movement of particles by natural unidirectional flow with low sediment concentrations (e.g., rivers, turbidity currents, pyroclastic flows). Bedforms and associated depositional structures: current ripples, dunes, upper-stage planar lamination, antidunes. Bedform stability fields.

Week 10: Sediment transport and structures under waves and tidal flow.
Movement of particles by oscillating and reversing flows in shallow water settings. Bedforms and associated depositional structures: wave ripples, hummocky and swaley cross stratification, herring bone cross stratification. Evidence for reversing flow and tidal signatures.

Week 11:Carbonate sedimentary rocks
Precipitation of carbonate from seawater. Carbonate factories – past and present. Reefs, mounds and carbonate sands and muds. Main limestone depositional environments. Post-depositional reactions – cements and dolomitisation.

Week 12: NO LECTURE.

Various materials will be available on Brightspace at the start of each week. Some provide information as preparation for practicals, in the form of videos, presentations or text documents. Others consist of online exercises, with self-assessment quizzes, to deepen your understanding of topics recently introduced in lectures.

Week 1
Practical preparation: The Motic petrological microscope: its parts and their functions. (mp4 video)
Exercise: Information and self-assessment related to the Periodic Table – elements, chemical symbols, atoms, ions, ionic charge and radius, co-ordination numbers, chemical bonds and chemical formulae.

Week 2
Practical preparation: Introduction to description of mineral hand specimen properties (mp4 video) and Description of mineral properites from online 3D rotatable images (mp4 video).
Exercise: Description of mineral properites from online 3D rotatable images.

Week 3
Exercise: Information and self-assessment on: silicate polymerization and atomic structures; classification of silicate minerals; the behaviour of aluminium in silicate minerals; element substitution, solid solution chemistry and its graphical representation.

Week 4
Exercise: Information and self-assessment on: plotting, calculations and interpretations related to phase diagrams, including binary crystal-liquid (anorthite-diopside, plagioclase), solvus (alkali feldspar) and polymorphic pressure - temperature (SiO2, Al2SiO5) examples.

Week 5
Practical preparation: How to use the virtual microscope (mp4 video) and Construction of a mineral identification key for use in the mid-trimester class test.

Week 7
Exercise: Sedimentary rocks of Ireland
Exploration of the bedrock geology. Types and ages of ancient sediments and their depositional environments. Applied and commercial aspects of sediments and sedimentary rocks. The exercise will be self-assessed and will utilise the Geological Survey of Ireland’s online GIS application.

Week 8
Exercise: Sandstones in thin section
The common components of sandstones that can be seen under thin section. Consideration of sandstone physical and compositional texture. The exercise will be self-assessed and will utilise the Virtual Microscope website.

Week 9
Exercise: Basic fluid dynamics and sediment transport theory
Information and self-assessment on: fluid properties, flow rheology, describing fluid flow (steady vs. unsteady flow, uniform vs. nonuniform flow, subcritical vs. supercritical flow, laminar vs. turbulent flow), velocity profiles, particle transport mechanisms, hydraulic boundary layer, threshold of particle motion and suspension.

Week 10
Exercise: Aeolian deposits and bedforms
Sediment transport in aeolian environments, typical characteristic of aeolian deposits (deflation lags, desert varnishing, grain rounding and surficial cements), aeolian bedforms (impact ripples, dunes and draas), internal structure of dunes, dust deposits.

Week 11
Practical preparation: Information on limestone components and limestone classification. Self assessment on identifying and naming limestones using microscope images.

Practical classes will be 3 hours long starting at 3.00 pm on Wednesdays in room G01, Science West.
You will be provided with mineral and rock specimens, a practical notebook and various small items of equipment such as a hand lens and a stick of glue to fix practical handouts in your notebook. You will also be provided with a microscope and thin sections. Apart from the notebook, all of this is on loan to you and must not be removed from the lab.

Weeks 1 – 5 (mineralogy)
At the end of each practical class, you should hand up your practical notebook so that you can be given feedback on your work.

Week 1: Introduction to the petrological (polarizing) microscope; description of the properties of minerals in granite (quartz, plagioclase, microcline, orthoclase, biotite, muscovite) in thin section.

Week 2: Description of common rock-forming minerals in hand specimen, using both online 3D rotatable images and physical specimens.

Week 3: Description of calcite, aragonite and dolomite in hand specimen and of calcite and dolomite in carbonate sedimentary rock. Description in thin section of coarse sand and comparison with the same minerals in granite.

Week 4: Description of augite, hypersthene, hornblende, olivine, serpentine and magnetite in thin sections of igneous and altered igneous rocks; how to distinguish between them. Extinction angles of mafic minerals and mineral identification. The use of igneous minerals and textures in understanding the origin of magmas and crystallization of igneous rocks.

Week 5: Description of andalusite, kyanite, sillimanite, epidote and garnet in thin section. The use of metamorphic minerals and their textures in understanding metamorphic history.

Weeks 7 – 11 (sediments and sedimentary rocks)

Week 7: Quantification of grain size using simple statistics to describe modern and ancient sediments. Evaluation of grain size variations in rivers. Use of Excel to automate calculations and graphing.

Week 8: Description of sandstones in hand specimen and in thin section. Sorting and grain rounding and link to depositional processes. Porosity and compaction fabrics. Cement and style of distribution. QFL classification.

Week 9: Exploring sediment transport and bedform development using flume experiments. Open channel flow and turbidity current experiments. Bedload vs. suspended load. Bedforms formed by open channel flow.

Week 10: Deriving flow direction from sedimentary structures and plotting directional data. Azimuthal vs. lineation data. Rose diagrams. Circular statistics. Variation in flow direction in natural river systems.

Week 11: Limestone depositional environments and environmental change based on sedimentary structures, hand specimens and thin-sections.

Student Effort Hours: 
Student Effort Type Hours




Autonomous Student Learning


Online Learning




Approaches to Teaching and Learning:
All lectures and practical classes will be given face-to-face, assuming that Covid-19 regulations permit this; if not, then both lectures and practical classes will be presented online. The module consists of linked lectures and practical classes , with exercises and information on Brightspace. The online exercises with built-in self-test questions further develop key topics introduced in some of the lectures. Online information is provided as preparation for some of the practical classes, especially where new techniques are to be used for the first time. Practical classes cover use of mineral hand specimens, but especially the petrological microscope, to study the properties of minerals and draw conclusions about how they formed. An online virtual microscope will be introduced and will serve as a revision resource for practical work. 
Requirements, Exclusions and Recommendations

Not applicable to this module.

Module Requisites and Incompatibles
GEOL10020 - Earth Science and Materials, GEOL10060 - Introduction to Earth Sciences

GEOL20120 - Investigating Minerals, GEOL20190 - Sedimentology & Palaeobiology

Additional Information:
Students must have passed either GEOL10060 or GEOL10020 as a prerequisite.

Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade In Module Component Repeat Offered
Class Test: Mid term examination of theory and practical work in first part of course Week 6 n/a Standard conversion grade scale 40% No


Examination: Combined written and practical examination cover second half of module Unspecified No Standard conversion grade scale 40% No



Carry forward of passed components
Resit In Terminal Exam
Spring Yes - 2 Hour
Please see Student Jargon Buster for more information about remediation types and timing. 
Feedback Strategy/Strategies

• Feedback individually to students, on an activity or draft prior to summative assessment
• Feedback individually to students, post-assessment
• Group/class feedback, post-assessment

How will my Feedback be Delivered?

The first half of the module is assessed by a mid-trimester class test. It consists of two parts: 1) short-answer questions on theory and 2) microscope-based exercises to test ability to describe and identify minerals. You will be allowed to consult your laboratory notebook during the microscopy part of the mid-trimester test. The second half of the module will be assessed by an end-trimester class test and will again comprise two parts: 1) short-answer questions on clastic and carbonate sedimentary rocks, and 2) a practical exercise in which you will describe and interpret a sedimentary succession. This will be a closed book test. Written individual feedback will be given the following week on practical work submitted at the end of practical classes. Feedback to the whole class will be given orally in practical classes.


First half of module – crystals, minerals, optical mineralogy, petrology

Digital copies of two mineralogy textbooks are provided on Brightspace (My Learning, Information about Weeks 1-6). These may be enough for your needs, but a few others that may be useful are listed below. These books are for support and reference with respect to the topics covered in lectures, practicals and online materials. You are not required to know or understand their entire contents!

1) Introduction to mineralogy and petrology (2014) by S. K. Haldar and Josip Tisljar
Persistent link:
This book will support your study of the topics covered in the lectures and online exercises – use it to help with things you don’t understand.

2) Optical mineralogy: principles and practice (1992) by C.D. Gribble and A.J. Hall
Persistent link:
This book will give you the optical theory behind the petrological microscope and information about using the microscope and mineral properties – use it as a reference to support your practical work.

Printed books:
• Minerals in Thin Section, 2nd edition, (2004) by D. Perkins and K.R. Henke
• Introduction to Mineralogy (2000) by W.D. Nesse
• An Introduction to the Practical Study of Crystals, Minerals and Rocks (1988) by K.G. Cox, N.B. Price and B. Harte
• Mineralogy for Students, 3rd edition, (1997) by M.H. Battey and A. Pring.

Second half of module – sediment and sedimentary rocks

1) Sedimentary Structures (2019) by J. Collinson & N. Mountney.
This book provides a thorough summary of different types of sedimentary structure and how they form supporting lectures on clastic sedimentology.

2) Sedimentology and Stratigraphy (2009) by G. Nichols.
For those wishing to explore other aspects of sedimentology and stratigraphy this book is an excellent place to start.

3) Origin of Carbonate Sedimentary Rocks (2015) by N. P. James and B. Jones
This book contains a wealth of information including a useful glossary – dip into it to expand on topics covered in the lecture and the online material.

Name Role
Dr Lawrence Amy Lecturer / Co-Lecturer
Assoc Professor Julian Menuge Lecturer / Co-Lecturer
Giorgia Ballabio Tutor
Amy Myers Tutor