Book contents
- Frontmatter
- Contents
- Preface
- 1 Periodicity and symmetry
- 2 Anisotropy and physical properties
- 3 Diffraction and imaging
- 4 Spectroscopic methods
- 5 The crystal structure of minerals – I
- 6 The crystal structure of minerals II – silicates
- 7 Defects in minerals, page 185 to 211
- Defects in minerals, page 212 to 238
- 8 Energetics and mineral stability I – basic concepts
- 9 Energetics and mineral stability II – solid solutions, exsolution and ordering
- 10 Kinetics of mineral processes
- 11 Transformation processes in minerals I: exsolution
- 12 Transformation processes in minerals II: structural phase transitions
- Index
5 - The crystal structure of minerals – I
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 Periodicity and symmetry
- 2 Anisotropy and physical properties
- 3 Diffraction and imaging
- 4 Spectroscopic methods
- 5 The crystal structure of minerals – I
- 6 The crystal structure of minerals II – silicates
- 7 Defects in minerals, page 185 to 211
- Defects in minerals, page 212 to 238
- 8 Energetics and mineral stability I – basic concepts
- 9 Energetics and mineral stability II – solid solutions, exsolution and ordering
- 10 Kinetics of mineral processes
- 11 Transformation processes in minerals I: exsolution
- 12 Transformation processes in minerals II: structural phase transitions
- Index
Summary
The ultimate reason for any particular arrangement between the atoms in a mineral structure must lie in the nature of the cohesive forces which hold the structure together, and the equilibrium between these interatomic forces determines their mutual positions. Thus it would be logical to try to develop a classification of crystal structures such that the geometrical description could be related to the symmetries of electron orbits around nuclei. While this is an instructive exercise in a few simple cases, the vast majority of minerals have such complex structures with mixed bonding types that it is not possible at present to predict the structure from the composition. Therefore after a brief general discussion of the relationship between structure and bonding, most of this chapter will deal with the geometrical concepts of space filling, and polyhedral arrangements to describe mineral structures. It is not the aim here to provide a systematic account of all of the important mineral structures, and we will be more concerned with outlining the general principles involved in such a description.
The fundamental question of the extent to which we can predict a mineral structure from theory, and the recent advances that have been made in the computer simulation of structures is discussed in Chapter 8.
Bonding in crystal structures
The cohesive forces between atoms are determined by the distribution of the outer, or valency, electrons. When atoms participate in bonding these outer electrons interact in ways which determine the symmetry of the atomic structure.
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- An Introduction to Mineral Sciences , pp. 121 - 140Publisher: Cambridge University PressPrint publication year: 1992
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