Some Facts About Ore Deposits By G. Montague Butler 1935 Soft Cover

Description: RailroadTreasures offers the following item: Some Facts About Ore Deposits By G. Montague Butler 1935 Soft Cover Some Facts About Ore Deposits By G. Montague Butler Arizona Bureau Of Mines, Geological Series No. 8 August 15 1935 Bulletin No. 139 PUBLISHED BY University of Arizona TUCSON, ARIZONA PREFACE This little book consists principally of a series of articles that appeared during 1919 and 1920 in the Arizona Mining Journal (now the Mining Journal) , published at Phoenix, Arizona.* Each chapter represents one article, and, in most instances, no material changes have been made in these articles, although the last two chapters and the appendices are new and some material has been added to each of the other chapters in order to bring them up to date. The series was originally written for prospectors or miners who are interested in the theoretical aspects of their vocation, and who are honestly seeking to learn the truth. So many mining engineers, geologists, and students of these subjects have, however, commented favorably upon the articles and expressed a desire to obtain them in book form that it is hoped they will prove to have some value to a wider audience than that for which they were originally written. The statements made are not original contributions to knowl-edge, and rarely represent merely the personal opinions and ideas of the writer. In most instances the convictions expressed are the common heritage of all students of geology and mining, and may be accepted unquestionably as representing the concensus of opinion of the great majority of such men. The assertions set forth cannot all be proven, and no attempt to prove them is made; they are the fruit of diligent and careful observations made by thousands of scientists and mining engineers scattered all over the world. While time may prove some of them to be incorrect, and will doubtless add much to our knowledge of several of the points discussed, most of the views presented may be accepted as having become so firmly established that there is small possibility that they will ever be successfully assailed. It has been necessary to indulge in broad generalizations, and it is admitted that numerous exceptions exist to specific rules given. It is believed, however, that it would prove confusing to discuss such exceptions. Most of the chapters were originally published as part of a series entitled, "Some Common Mining Fallacies." It has been the aim of the writer, however, not so much to lay emphasis upon "Mining. Fallacies" formed, then, merely a pretext for the presentation of facts, or what the majority of mining geologists believe to be facts; and no apology seems necessary when comparatively little is said about fallacies and much about facts, as is the case in several of the chapters. It is realized that some of the topics very briefly presented herewith might profitably be greatly expanded, but it was not the desire of the writer to trespass upon the field of several excellent and exhaustive treatises already in print, to which reference is made in the bibliography. It is hoped that many readers will be led to seek in these works further light on sub-jects of such interest and importance to our mineral industries. While, as previously stated, almost every fact herein presented has already appeared in print, most of the chapters were written from memory without immediate reference to the literature of the subject, and it would require a vast amount of time and trouble to locate the sources of the data set forth. The writer sincerely regrets that he is not in a position to give proper credit for his ideas, and offers his apologies to anyone who may feel that his work has been slighted. Doctor B. S. Butler and Doctor R. J. Leonard have read the manuscript critically, and the writer has adopted a number of suggestions made by them. His sincere thanks are extended to them for their invaluable assistance and encouragement. G. M. BUTLER. August 15, 1935. TABLE OF CONTENTS CHAPTER PAGE I.-The Higher Values with Increased Depth Myth 7 A Widespread, but Fallacious, Belief 7 The Deposition of Ore 7 Ore Deposits Usually Decrease in Value with Increasing Depth 9 Explanation of the Prevalence of the Fallacy 10 Conclusion 11 II.-The Change of Character of Ore with Increased Depth Myth 13 The Facts 13 The Primary Ore Zones 14 The Silver Zone 15 The Lead Zone 16 The Zinc Zone 16 The Arsenic Zone 16 The Copper Zone 16 The Iron-Gold Zone 17 The Rare Metals or Pegmatite Zone 17 Other Facts Relating to the Primary Ore Zones 17 Emmons' Table of Ore Zones 18 Arrangement of Deposits in Zones on the Surface 20 Examples 21 III.-Some Myths Relating to Leaching 23 Some False Ideas Stated 23 Veins and Similar Structures Do Not Always Contain Valuable Minerals 23 Some Minerals Are Not Normally Subject to Leaching 23 Leaching or Mechanical Removal of Valueless Minerals May Result in Enrichment 25 IV.-Some Myths Relating to Secondary Enrichment 28 Secondary Enrichment Defined 28 Enriching Processes 28 The Secondary Enrichment of Gold 29 The Secondary Enrichment of Sulphides 31 Some Fallacious Ideas 34 Important Influence of Carbonates 35 V.-The Phonolite Myth 37 The Title Explained 37 The Rocks Associated with Gold Deposits 38 The Rocks Associated with Silver Deposits 39 The Rocks Associated with Lead and Zinc Deposits 39 The Rocks Associated with Copper Deposits 40 The Rocks Associated with Mercury Deposits 40 The Rocks Associated with Chromium Deposits 40 The Rocks Associated with Tin Deposits 40 The Rocks Associated with Tungsten Deposits 41 The Rocks Associated with Platinum Deposits 41 CHAPTERPAGE VI-Some Myths Relating to Outcrops 43 Introductory 43 Valuable Deposits Not Always Marked by Prominent Outcrops 43 Veins Do Not Always Widen Below Their Outcrops 45 No Fixed Relationship Exists Between Length of Outcrop and Depth to Which Development May Profitably be Carried 46 The Presence of Certain Species of Plants Not a Very Reliable Indication of the Existence of an Outcrop 47 Additional Observations on Outcrops 48 VII.-The Blowout Myth 51 Foreword 51 A Blowout Defined 51 Few Mineral Deposits Were Originally Molten 51 "Burnt" Outcrops Not Necessarily Indicative of Volcanic Activity 52 Ore Deposits Not Invariably Precipitated from Water Solutions 53 The Facts About So-called Blowouts 54 VIII.-Some Fallacies Relating to Ore Shoots 58 An Ore Shoot Defined 58 The Nature of Ore Shoots 59 Conditions Favoring the Formation of Ore Shoots 59 Veins and Mineralized Structures Do Not Always Contain Ore Shoots 61 Ore Shoots Not Always Found Where Conditions Seem Favorable 62 Conditions Favoring the Development of Ore Shoots in One Lo- cality May Not Do So Elsewhere 63 No Fixed Relation Exists Between the Horizontal and Vertical Dimensions of Ore Shoots 64 IX.-The Aluminum Myth 65 An Erroneous Idea 65 The Facts About Aluminum 65 Other Valuable Substances Unrecoverable from Some of their Compounds 67 The Myth Illustrated 68 Remarks on Complete Analyses 69 X.-The Divining Rod Myth 71 An Ancient and Widely Held Idea 71 Nature of Instruments Used 71 Possibility that Divining Rods May Have Been Used Successfully 72 All Users Not Imposters 72 Facts Bearing on the Solution of the Problem 73 Theories Explaining the Action of Divining Rods 73 Divining Rods and Geophysical Instruments Differentiated 76 Classification of Geophysical Methods 76 Practical Value of Geophysics 77 Appendix A.-Brief Descriptions of Minerals Mentioned 79 Appendix B.-Rocks 94 Igneous Rocks 94 Clastic Rocks 94 Chemical Precipitate Rocks 95 Organic Rocks 95 Metamorphic Rocks 95 Description of Rock Species Mentioned 95 Selected Bibliography 99 All pictures are of the actual item. 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Price: 50 USD

Location: Talbott, Tennessee

End Time: 2024-11-25T19:31:41.000Z

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