Chemical Fundamentals of Geology and Environmental Geoscience

Robin Gill lectured in geochemistry and igneous petrology at the University of London for 22 years, and before that held postdoctoral posts at the Universities of Manchester, Western Ontario and Oxford. His other books include Igneous Rocks and Processes: A Practical Guide (2010) and Modern Analytical Geochemistry (editor, 1997)

PREFACE TO THE THIRD EDITION ix

PREFACE TO THE SECOND EDITION x

PREFACE TO THE FIRST EDITION xi

ACKNOWLEDGEMENTS xiii

ABOUT THE COMPANION WEBSITE xiv

1 ENERGY IN GEOCHEMICAL PROCESSES 1

Introduction 1

Energy in mechanical systems 4

Energy in chemical and mineral systems: free energy 5

Stable, unstable and metastable minerals 10

Further reading 13

2 EQUILIBRIUM IN GEOLOGICAL SYSTEMS 14

The significance of mineral stability 14

Systems, phases and components 16

Equilibrium 18

Phase diagrams in P–T space 20

Phase diagrams in T–X space 26

Ternary phase diagrams 36

Review 41

Further reading 41

Sources of thermodynamic data for minerals 42

Exercises 42

3 KINETICS OF EARTH PROCESSES 43

Defining the rate of a reaction 44

Temperature-dependence of reaction rate 47

Diffusion 52

Melt viscosity 55

Persistence of metastable minerals: closure temperature 57

Review 58

Further reading 58

Exercises 59

4 AQUEOUS SOLUTIONS AND THE HYDROSPHERE 60

Ways of expressing the concentrations of major constituents 61

Equilibrium constant 63

Non-ideal solutions: activity coefficient 69

Natural waters 70

Oxidation and reduction: Eh-pH diagrams 75

Further reading 81

Exercises 81

5 ELECTRONS IN ATOMS 82

Why does a geologist need to understand atoms? 82

The atom 83

Stationary waves 85

Electron waves in atoms 88

The shapes of electron orbitals 90

Electron energy levels 93

Review 98

Further reading 98

Exercises 98

6 WHAT WE CAN LEARN FROM THE PERIODIC TABLE 99

Ionization energy 99

The Periodic Table 102

Electronegativity 103

Valency 104

Atomic spectra 105

Review 109

Further reading 110

Exercises 110

7 CHEMICAL BONDING AND THE PROPERTIES OF MINERALS 111

The ionic model of bonding 111

The covalent model of bonding 118

Bonding in minerals 126

Other types of atomic and molecular interaction 129

Review 132

Further reading 132

Exercises 132

8 SILICATE CRYSTALS AND MELTS 133

Silicate polymers 133

Cation sites in silicates 140

Optical properties of crystals 146

Defects in crystals 148

Further reading 151

Exercises 151

9 SOME GEOLOGICALLY IMPORTANT ELEMENTS 153

Major and trace elements 153

Alkali metals 154

Hydrogen 156

Alkaline earth metals 156

Aluminium 157

Carbon 159

Silicon 166

Nitrogen and phosphorus 166

Oxygen 167

Sulfur 168

Fluorine 170

Noble gases 171

Transition metals 171

Rare earth elements 175

Actinides 176

Further reading 177

Exercise 177

10 WHAT CAN WE LEARN FROM ISOTOPES? 178

Isotope systems 179

Radiogenic isotope systems 181

Stable isotope systems 195

Cosmogenic radioisotope systems 203

Review 204

Further reading 204

Exercises 204

11 THE ELEMENTS IN THE UNIVERSE 206

The significance of element abundance 206

Measuring cosmic and Solar System abundances 206

The composite abundance curve 210

Cosmic element production 211

Elements in the Solar System 215

Chemical evolution of the Earth 219

Review 224

Further reading 225

Exercises 225

ANSWERS TO EXERCISES 226

APPENDIX A: Mathematics revision 234

APPENDIX B: Simple solution chemistry 240

APPENDIX C: Alphabetical list of chemical abbreviations and element names, with atomic number and relative atomic mass 243

APPENDIX D: Symbols, units, constants and abbreviations used in this book 245

Glossary 248

REFERENCES 258

INDEX 261