ELEMENTS OF MINERALOGY RUTLEY'S ELEMENTS OF MINERALOGY Twenty-Sixth Edition H. H. READ, F.R.S. Professor Emeritus of Geology in the Imperial College of Science and Technology and the University of London LONDON THOMAS MURBY & CO NINETEENTH EDITION, THOROUGHLY REVISED, RESET, AND NEW ILLUSTRATIONS, 1915 TWENTIETH EDITION 1918 SECOND IMPRESSION 1919 TWENTY-FIRST EDITION 1921 SECOND IMPRESSION WITH SLIGHT CORRECTIONS 1923 THIRD IMPRESSION 1926 TWENTY-SECOND EDITION 1929 SECOND IMPRESSION 1933 TWENTY-THIRD EDITION, THOROUGHLY REVISED, RESET, AND NEW ILLUSTRATIONS, 1936 SECOND IMPRESSION 1939 THIRD IMPRESSION 1942 FOURTH IMPRESSION 1944 FIFTH IMPRESSION 1946 TWENTY-FOURTH EDITION 1948 SECOND IMPRESSION 1949 THIRD IMPRESSION 1953 FOURTH IMPRESSION 1956 FIFTH IMPRESSION 1957 SIXTH IMPRESSION 1960 TWENTY-FIFTH EDITION 1962 TWENTY -SIXTH EDITION 1970 COMPLETELY REVISED, RESET AND MANY NEW ILLUSTRATIONS SECOND IMPRESSION 1971 THIRD IMPRESSION 1973 FOURTH IMPRESSION 1975 FIFTH IMPRESSION 1976 This book is copyright under the Berne Convention. All rights are reserved. Apart from any fair dealing for the purpose of private study, criticism or review, as permitted under the Copyright Act, 1956, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, electrical, chemical, mechanical, optical, photo copying, recording or otherwise, without the prior permission of the copyright owner. Enquiries should be addressed to the Publishers. This twenty-sixth edition © George AI/en & Unwin (Publishers) Ltd. 1970 ISBN 978-0-04-549006-6 ISBN 978-94-011-9769-4 (eBook) DOI 10.1007/978-94-011-9769-4 George Allen & Unwin Ltd., 40 Museum Street, London W.C.I are the proprietors of Thomas Murby & Co. in lOon 11 point Times BY JOLLY AND BARBER LTD RUGBY vii PREFACE The last thorough revision of Rutley's Elements of Mineralogy appeared as the 23rd Edition in 1936. In subsequent editions, an effort to keep abreast with the great progress in the science was made by small (and often awkward) modifications and, especially, by the addition of an independent chapter on the atomic structure of minerals. For this present edition, the complete re-setting of the book has made possible not only the integration of the added chapter on atomic structure into its proper place in the accounts of the chemical and physical properties of minerals, but also extensive rewriting and rearrangement of the material in the first part of the book. To this part, also, has been added a short chapter on the classification of minerals. In the second part, the Descrip tion of Minerals, numerous, if not so extensive, modifications and modernisations have been introduced. A couple of dozen new figures have been added, mostly in the early part of the book. More specifically, the major changes in this new edition are the following. The electronic structure of atoms supplies the guide lines for the whole account of mineral-chemistry; additional items concern the electrochemical series, of interest in the occurrence and metallurgical treatment of ores, and chemical analysis. On the physical side, the dependence of physical properties of minerals on their atomic structure is emphasized and, in addition, a brief account of radioactivity and isotopic age-determination is given. Crystal-structure, of course, enters largely into the formal presentation of the morphology of crystals; here, too, the crystallographic nomenclature is modern ized and an elementary introduction to stereographic projection and its use in the description of crystal-symmetry is inserted. The chapter on the occurrence of minerals has been partly rewritten to include extended accounts of the sedimentary and meta morphic rocks and the different types of economic mineral deposits; a summary of earth-history is given, together with some age-data. The new chapter on the classification of minerals defends that used in this book; in this, minerals are assembled into economic groups according to elements, and the elements are associated according to the Periodic Classification - this classi- viii fication has stood the test of time as suitable for the wide public for whom the book is intended. In Part II, Description of Minerals, the uses and occurrences of minerals are brought up to date, crystal structures of the rock forming minerals are introduced and modem methods of extrac tion of the metals from their ores mentioned. Some metals of importance in nuclear energy and space-research are briefly noted. My first revision of 'Rutley' was undertaken more than half a century ago - I trust that this present effort will be as useful in its limited objectives as its predecessors. During this long span I have received invaluable help from a great number of friends as recorded in previous prefaces, and to these I re-offer my grateful thanks. In this present revision I am specially indebted to Dr. F. G. H. Blyth for his critical reading of some of the manuscript and for providing certain of the figure-drawings. Dr. Janet Watson has read the whole text and contributed greatly to its clarity and, besides, has drawn many of the new figures. Finally, she has helped to see the book through the press. For such willing assistance in making it possible for me to complete this work, I offer her my sincere gratitude. My thanks are also due to Mr. J. A. Gee and Mr. R. Curtis, both of the Geology Department, Imperial College, for kindly supplying photographs for Figures 2, 13 and 14 and for Figure 17 respectively; and to James Swift & Son Ltd for the photograph for Figure 99 H.H.READ ix TABLE OF CONTENTS WITH LIST OF MAIN TOPICS PREFACE Page INTRODUCTORY: lHE NATURE OF MINERALS I Definition of a Mineral 3 PART I. THE PROPERTIES OF MINERALS CHAPTER I. THE CHEMISTRY OF MINERALS 9 Elements and Atoms 9 The Structure of the Atom 11 Atomic Bonding 17 Ionic Radii 24 Periodic Classification of the Elements 26 Chemical Compounds 28 Chemical Analysis 31 Analysis by the Blowpipe 33 Tables of Blowpipe Analysis 40 CHAPTER II. CERTAIN PHYSICAL PROPERTIES OF MINERALS 48 i. Colour, Lustre, Transparency etc. 48 iL Taste, Odour and Feel 52 iii. State of Aggregation 53 Form 53 Pseudomorphism 55 Polymorphism 56 Hardness 56 Fracture 59 Cleavage and Parting 60 iv. Specific Gravity 63 v. Characters dependent upon Heat 69 vi .. Characters dependent upon Magnetism, Electricity and Radioactivity 69 CHAPTER III. THE ELEMENTS OF CRYSTALLOGRAPHY 73 Crystal Structure 74 The Unit Cell 76 External Characteristics of Crystals 79 Symmetry 83 The Crystal Systems 94 LCubic or Isometric System 96 x CONTENTS Page I. Galena Type 97 2. Pyrite Type 104 3. Tetrahedrite Type 106 Stereographic Representation of Crystal Symmetry 110 II. Tetragonal System 113 4. Zircon Type 114 iii. Hexagonal System 120 5. Beryl Type 121 6. Calcite Type 124 7. Tourmaline Type 129 8. Quartz Type 132 iv. Orthorhombic System 138 9. Barytes Type 138 v. Monoclinic System 142 10. Gypsum Type 143 VI. Tric1inic System 147 11. Axinite Type 148 Crystal Aggregates 150 Twin Crystals 151 CHAPTER IV. THE OPTICAL PROPERTIES OF MINERALS 157 The Nature of Light 157 Refractive Index 161 Double Refraction 167 Optically Uniaxial Minerals 168 The Nicol Prism 170 The Petrological Microscope 171 Minerals between Crossed Nicols 173 Vibration-Directions and Optic Orientation 180 Pleochroism and Absorption 183 Convergent Light 184 Interference Figures in Uniaxial Minerals 185 Biaxial Minerals 187 Interference Figures in Biaxial Minerals 189 Synopsis of Examination of Minerals under the Petrological Microscope 192 The Microscopic Investigation of Ore-Minerals 197 CHAPTER V. THE OCCURRENCE OF MINERALS 199 The Classification of Rocks 199 I. Igneous Rocks 199 2. Sedimentary Rocks 205 3. Metamorphic Rocks 208 Mineral Deposits 211 Endogenetic Mineral Deposits 213 Exogenetic Mineral Deposits 215 Supergene Enrichment of Mineral Deposits 216 Geological History 217 CONTENTS xi Page CHAPTER VI. THE CLASSIFICATION OF MINERALS 220 PART I!. DESCRIPTION OF MINERALS GROUP lA. LITHIUM, SODIUM, POTASSIUM Lithium Minerals 227 Sodium Minerals 228 Potassium Minerals 235 GROUPIB. COPPER, SILVER, GOLD Copper Minerals 241 Silver Minerals 255 Gold Minerals 262 GROUP 2A. CALCIUM, STRONTIUM, BARIUM, RADIUM Calcium Minerals 270 Strontium Minerals 285 Barium Minerals 287 Radium Minerals 291 GROUP2B. BERYLLIUM, MAGNESIUM, ZINC, CADMIUM, MERCURY Beryllium Minerals 292 Magnesium Minerals 294 Zinc Minerals 298 Cadmium Minerals 306 Mercury Minerals 307 GROUP 3B. BORON, ALUMINIUM Boron Minerals 312 Aluminium Minerals 317 GROUP4A. TITANIUM, ZIRCONIUM, CERIUM, THORIUM Titanium Minerals 327 Zirconium Minerals 331 Cerium and Thorium Minerals 333 GROUP 4B. CARBON, SILICON, TIN, LEAD Carbon Minerals 338 Silicon Minerals 348 Silicate Structures 349 Classification of Silicates 355 A. Nesosilicates 358 B. Sorosilicates 372 xii CONTENTS Page C ..C yclosilicates 376 D. Inosilicates 380 E. Phyllosilicates 399 F. Tectosilicates 417 Tin Minerals 452 Lead Minerals 456 GROUP 5A. VANADIUM, TANTALUM Vanadium Minerals 467 Tantalum Minerals 468 GROUP 5B. NITROGEN, PHOSPHORUS, ARSENIC, ANTIMONY, BISMUTH Nitrogen Minerals 471 Phosphorus Minerals 472 Arsenic Minerals 473 Antimony Minerals 478 Bismuth Minerals 483 GROUP 6A. CHROMIUM, MOLYBDENUM, TUNGSTEN, URANIUM Chromium Minerals 486 Molybdenum Minerals 487 Tungsten Minerals 490 Uranium (and Radium) Minerals 493 GROUP 6B. SULPHUR, SELENIUM, TELLURIUM Sulphur Minerals 497 Selenium Minerals 500 Tellurium Minerals 500 GROUP7A. MANGANESE Manganese Minerals 503 GROUP7B. FLUORINE, CHLORINE, BROMINE, IODINE Halogen Minerals 511 GROUP8A. IRON, COBALT, NICKEL Iron Minerals 513 Cobalt Minerals 528 Nickel Minerals 531 GROUP 8B. RUTHENIUM, RHODIUM, PALLADIUM, OSMIUM, IRIDIUM, PLATINUM Platinum Group Minerals 538 INDEX 542 INTRODUCTORY: THE NATURE OF MINERALS The Mineral Kingdom. It has long been the custom to divide nature into three great departments, the animal, vegetable and mineral kingdoms. The mineral kingdom comprises the materials that make the crust of the earth and a part of this kingdom is dealt with in the science of mineralogy. Whether or not any definite boundaries exist between the three kingdoms is a subject which remains to be investigated. The different members of the animal and vegetable kingdoms are characterized by the development of special organs, or of certain peculiarities of structure, by means of which they pass through a series of changes known as life and growth. This latter phenomenon takes place by the absorption of various kinds of matter which then undergoes conversion by chemical processes into substances similar to those making the plant or aniplal. In this way the waste which accompanies life is replaced. The bones and shells of animals consists to a great extent of mineral matter. Plants are capable of deriving earthy substances from the soil in which they grow. But mineral matter which has thus been utilized by organisms passes, in the rigid interpretation of the term, beyond the pale ofm ineralogy, for it assumes a structure, governed by the nature and requirements of the animal or plant, that it would not possess as an ordinary portion of the earth's crust. For example, a pearl would be regarded as an organic substance and not a true mineral, although it consists of mineral matter. Again, coal, being a substance derived from the decomposition of vegetable matter, would not be rigidly classed with minerals. Minerals. A most important characteristic of a mineral is the possession of a definite chemical composition. Some qualification of this statement is, however, necessary. Certain minerals form a closely related series in which there is a gradual replacement of