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The Carbonatite-Hosted Apatite Deposit of Jacupiranga, SE Brazil: Styles of Mineralization, Ore Characterization and Association with Mineral Processing

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The Carbonatite-Hosted Apatite Deposit of Jacupiranga, SE Brazil: Styles of Mineralization, Ore Characterization and Association with Mineral Processing Scholars' Mine Masters Theses Student Theses and Dissertations Spring 2008 The carbonatite-hosted apatite deposit of Jacupiranga, SE Brazil: styles of mineralization, ore characterization and association with mineral processing Paula Regina Alves Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Geology Commons, and the Geophysics and Seismology Commons Department: Recommended Citation Alves, Paula Regina, "The carbonatite-hosted apatite deposit of Jacupiranga, SE Brazil: styles of mineralization, ore characterization and association with mineral processing" (2008). Masters Theses. 6723. https://scholarsmine.mst.edu/masters_theses/6723 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. i THE CARBONATITE-HOSTED APATITE DEPOSIT OF JACUPIRANGA, SE BRAZIL: STYLES OF MINERALIZATION, ORE CHARACTERIZATION, AND ASSOCIATION WITH MINERAL PROCESSING by PAULA REGINA ALVES A THESIS Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE IN GEOLOGY 2008 Approved by R. D. Hagni, Advisor J. P. Hogan F. S. Miller ii iii ABSTRACT The carbonatite-hosted apatite deposit of Jacupiranga is located in southeastern Brazil. The major styles of apatite mineralization are veins or veinlets, small pods or patches, disseminated apatite, and massive aggregates (locally). The concentration of apatite involves grinding of the carbonatite, removal of magnetite with a magnet drum, size classification with cyclones, and flotation to suppress carbonates and collect apatite. Samples of carbonatite were collected from more recent exposures of the mine and drill holes. This study utilized a variety of microscopy methods, namely transmitted and reflected light, cathodoluminescence (CL), and scanning electron microscopy (with wavelength-dispersive spectrometers for mineral compositions). Results showed that LREE, Na and Sr are the main elements replacing Ca in the studied apatite, with relatively low oxide contents (< 0.5%, but up to about 1% for Sr). LREE and Sr contents consistently increase in the latest intrusions (C4, C5 and SP24). Chemical and morphological modifications in apatite identified in this work can be related to detrimental effects on flotation recovery. For instance, the reddish apatite was fractured, and some grains show no CL, probably as a result of quenching caused by iron entering the apatite structure, which has also changed its color. In the apatite from the xenolith-rich area, the elevated presence of fine, platy silicates may be interfering more with the lower flotation recovery than compositional variations. In the case of the “hard” apatite (more difficult to grind), most of the area where it occurs was affected by hydrothermal activity, as evidenced by the development of a bright, white CL rim in apatite, and the presence of late veins of carbonates and sulfides filling fractures and possibly resulting in higher cohesiveness of the grains. iv ACKNOWLEDGMENTS The completion of this thesis represents the culmination of a trajectory along which many people have contributed at different times and in different ways, but all very important. It started back in 2000, when Dr. Richard Dick Hagni, during a field trip to the Cajati mine, as part of the International Geological Congress, approached the mine geologist, who was showing the site to the visitors, about joining the group of graduate students of the University of Missouri-Rolla. The writer thanks Dick Hagni for all his great support along the road, for his dedication in recruiting students around the world, and for his lovely wife, who walked an extra mile to help the writer settle in Rolla upon her arrival. The initial adaptation in a foreign country, and many other circumstances, became much easier to overcome due to the constant support of the writer’s family, Ira, Michele, Priscila and Junior, many miles away but always present, as well as very special friends who have been always available during the difficult moments that are part of life. The development of this thesis also received the invaluable support from the Society of Economic Geologists, through the Hugh E. McKinstry research grant, from the colleagues with Bunge Brazil, allowing access to the mine and facilitating the field work, and from Dr. Maria Cristina Toledo Motta, a carbonatites enthusiast and professor at the Universidade de São Paulo, through fruitful discussions and access to the thin section preparation laboratory. The writer is also very thankful for the motivation received from the committee members, Dr. John Hogan and Dr. Scott Miller, from the Geology and Geophysics staff, and from Imerys Pigments, in the figure of Dr. Robert Pruett, for his support during the writing of this thesis. Finally, the writer would like to thank the fundamental assistance provided by the Josephine Husbands Radcliffe fund, through the granted teaching assistant scholarship. v TABLE OF CONTENTS Page ABSTRACT ..................................................................................................................iii ACKNOWLEDGMENTS............................................................................................. iv LIST OF ILLUSTRATIONS ....................................................................................... vii LIST OF TABLES ........................................................................................................ ix LIST OF PLATES.......................................................................................................... x SECTION 1. INTRODUCTION...................................................................................................... 1 1.1. OBJECTIVE AND RELEVANCE OF THE RESEARCH................................ 1 1.2. BRIEF HISTORY OF THE JACUPIRANGA IGNEOUS COMPLEX (JIC) ... 2 1.2.1. Discovery and Mapping of the Complex ................................................. 2 1.2.2. Mining Activities...................................................................................... 3 2. PETROLOGIC AND TECTONIC CONTEXT OF THE CARBONATITE............. 6 2.1. REGIONAL GEOLOGY AND TECTONIC SETTING.................................... 6 2.2. LITHOLOGIES OF THE JACUPIRANGA IGNEOUS COMPLEX (JIC)..... 10 3. METHODS............................................................................................................... 14 3.1. FIELD WORK.................................................................................................. 14 3.2. ANALYTICAL METHODS ............................................................................ 16 3.2.1. Petrography ............................................................................................ 17 3.2.2. Cathodoluminescence Microscopy......................................................... 17 3.2.3. Scanning Electron Microscopy and Electron Probe Micro-Analysis..... 20 4. RESULTS................................................................................................................. 22 4.1. THE APATITE ORE ........................................................................................ 22 4.1.1. Geochemical and Microscopic Aspects of the Apatite .......................... 25 4.1.2. Characteristics of the Apatite Mineralization......................................... 45 vi 4.2. THE GANGUE MINERALS ........................................................................... 47 4.2.1. Carbonates: Calcite and Dolomite.......................................................... 47 4.2.2. Oxides: Magnetite and Ilmenite ............................................................. 54 4.2.3. Silicates: Olivine and Phlogopite ........................................................... 62 4.2.4. Sulfides: Pyrrhotite, Pyrite, Chalcopyrite, Valleriite ............................. 72 4.2.5. Other Minerals........................................................................................ 77 5. DISCUSSIONS ........................................................................................................ 81 5.1. APATITE PROCESSING IN CAJATI ............................................................ 81 5.2. APATITE CHARACTERISTICS RELATED TO PROCESSING ISSUES ... 82 5.3. DEVELOPMENT OF THE MINERALIZATION: CONTRIBUTIONS FROM THE GANGUE MINERALS............................................................... 84 5.4. PETROGENETIC ASSOCIATION OF THE DOLOMITIC CARBONATITE SP 24 ................................................................................... 85 6. CONCLUSIONS...................................................................................................... 87 6.1. STYLES OF MINERALIZATION .................................................................. 87 6.2. ORE CHARACTERIZATION ......................................................................... 87 6.3. ASSOCIATION WITH MINERAL PROCESSING........................................ 88 APPENDICES A. PLATE SHOWING SELECTED DRILL CORES ................................................. 90 B. PLATES SHOWING SELECTED MICROGRAPHS............................................ 92 C. ESTIMATED MODAL COMPOSITIONS FOR SELECTED THIN SECTIONS ...........................................................................................................
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