Page 6 - A Practical Introduction to Optical Mineralogy

ACKNOWLEDGEMENTS
Contents
Accounts of transmitted-light optical crystallography and reflected-light
theory are therefore placed after the main descriptions of minerals, in
Chapters 4 and 5 respectively. The appendices include systematic lists of
the optical properties of minerals for use in identification. Preface page vii
This book is intended to be an aid to the identification of minerals
under the microscope, but not to the description or interpretation of Acknowledgements viii
mineral relationships. We both hope that the text fills its intended slot, List of tables xi
and that students find it helpful and enjoyable to use.
List of symbols and abbreviations used in text xii
1 Introduction to the microscopic study of minerals
1.1 Introduction 1
1.2 The transmitted-light microscope 1
1.3 Systematic description of minerals in thin section
using transmitted light 5
1.3.1 Properties in plane polarised light 5
Acknowledgements 1.3.2 Properties under crossed polars 8
1.4 The reflected-light microscope 12
1:5 The appearance of polished sections under the
The sections dealing with transmitted light have been written by C. D. reflected-light microscope 17
1.6 Systematic description of minerals in polished section
Gribble. He acknowledges the debt owed to Kerr (1977), whose format
using reflected light 19
has generally been employed in Chapter 2, and to Deer et al. (1966),
1.6.1 Properties observed using plane polarised
whose sections on physical properties and mineral paragenesis have
light (PPL) 19
often been the basis of the RI values and occurrences given in this text.
1.6.2 Properties observed using crossed polars 20
Other authors and papers have been employed, in particular Smith
1.6.3 The external nature of grains 21
(1974) on the feldspars and Wahlstrom (1959) on optical crystallo-
1.6.4 Internal properties of grains 21
graphy.
Descriptions of the opaque minerals by A. J. Hall are based on data in 1.6.5 Vickers hardness number (VHN) 22
many texts. However, they are taken mainly from the tables of Uyten- 1.6.6 Distinguishing features 22
bogaardt and Burke (1971), the classic text Dana's system of mineralogy 1. 7 Observations using oil immersion in reflected-light
edited by Palache et al. (1962), the unsurpassed description of the studies 22
textures of the ore minerals by Ramdohr (1969), and the atlas by Picot 1.8 Polishing hardness 23
1.9 Microhardness (VHN) 25
and Johan (1977). The textbook on the microscopic study of minerals by
1.10 Points on the use of the microscope (transmitted and
Galopin and Henry (1972), and course notes and publications of
reflected light) 26
Cervelle, form the basis of the section on theoretical aspects of
1.11 Thin- and polished-section preparation 28
reflected-light microscopy.
The Michel-Levy chart on the back cover is reproduced with the kind
permission of Carl Zeiss of Oberkochen, Federal Republic of Germany. 2 Silicate minerals
We are grateful for support and suggestions by our colleagues in the 2.1 Crystal chemistry of silicate minerals 30
Universities of Glasgow and Strathclyde. A special thanks is due to the 2.2 Mineral descriptions 34
typists Janette Forbes, Irene Wells, Dorothy Rae, Irene Elder and Mary Al2Si0 5 polymorphs 35; Amphibole group 41;
Fortune. Beryl 56; Chlorite 57; Chloritoid 58; Clay
Also, we are particularly grateful to John Wadsworth and Fergus minerals 59; Cordierite 61 ; Epidote group 63;
Gibb for their comments and reviews of the original manuscript, and to Feldspar group 67; Feldspathoid family 84;
Brian Goodale for his comments on Chapter 4. Garnet group 87; Humite group 88; Mica group 90;
Any errors or inaccuracies are, however, ours. Olivine group 95; Pumpellyite 98; Pyroxene group 99;
viii ix