University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2017 Fingerprinting Wolframite: An Atomic/ crystallographic, Chemical And Spectroscopic Study Along The olidS Solution Series Gina Marie Accorsi University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Earth Sciences Commons Recommended Citation Accorsi, Gina Marie, "Fingerprinting Wolframite: An Atomic/crystallographic, Chemical And Spectroscopic Study Along The oS lid Solution Series" (2017). Graduate College Dissertations and Theses. 710. https://scholarworks.uvm.edu/graddis/710 This Thesis is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. FINGERPRINTING WOLFRAMITE: AN ATOMIC/CRYSTALLOGRAPHIC, CHEMICAL AND SPECTROSCOPIC STUDY ALONG THE SOLID SOLUTION SERIES A Thesis Presented by Gina Accorsi to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Master of Science Specializing in Geology May, 2017 Defense Date: March 20, 2017 Thesis Examination Committee: John M. Hughes, Ph.D., Advisor Robert V. Bartlett, Ph.D., Chairperson Laura E. Webb, Ph.D. Cynthia J. Forehand, Ph.D., Dean of the Graduate College ABSTRACT In accordance with the 2010 Dodd-Frank Act, conflict minerals refer to gold, tantalum, tin, and tungsten bearing minerals sourced from the Democratic Republic of Congo (DRC) that have been mined illegally and used to funnel funds to rebel forces. In response to an increasing demand for these metals used in cellphones, computers, and other popular technologies, Dodd-Frank mandates that industrial consumers demonstrate due diligence and assure that the materials they use have been extracted legally. Because current chain-of-custody methods have not been effective in sourcing ores, a study was undertaken whereby the range of mineralogical characteristics of 15 samples along the wolframite solid solution series were determined in order to ascertain if differences in these characteristics would permit fingerprinting of the source deposit of wolframite, of which the DRC is the world’s fifth largest producer. For these 15 samples, single-crystal X-ray structure and powder X-ray diffraction studies have been conducted; major, minor and trace element chemistry has been determined using ICP-MS and ICP-OES; and Raman spectroscopy has been carried out. Finally, statistical methods were used to determine relationships between samples, and the results of that mathematical work show that there is no firm method at the present time of determining the provenance of a sample based on the information of the crystal structure, diffraction patterns, vibrational frequencies/scattering, or major and trace elemental chemistry. This study elucidates the range of mineralogical properties along the hübnerite- ferberite solid solution series while working towards to development of an analytical technique that is affordable, practical, accessible and effective for industrial consumers seeking product certification and compliance with the 2010 Dodd-Frank Act. TABLE OF CONTENTS Page LIST OF TABLES ............................................................................................................. iii LIST OF FIGURES ........................................................................................................... iv CHAPTER 1: INTRODUCTION ........................................................................................1 CHAPTER 2: METHODS ...................................................................................................6 2.1. Background ...............................................................................................................6 2.2. SC-XRD ....................................................................................................................8 2.3. ICP-MS and ICP-OES ..............................................................................................8 2.4. P-XRD.......................................................................................................................9 2.5. Raman Spectroscopy .................................................................................................9 2.6. Data Analysis ..........................................................................................................10 CHAPTER 3: RESULTS ...................................................................................................11 3.1. SC-XRD ..................................................................................................................11 3.2. ICP-MS/OES...........................................................................................................29 3.3. P-XRD.....................................................................................................................36 3.4. Raman .....................................................................................................................37 3.5. Statistics ..................................................................................................................38 CHAPTER 4: DISCUSSION .............................................................................................43 CHAPTER 5: CONCLUSIONS ........................................................................................46 REFERENCES CITED ......................................................................................................51 APPENDIX ........................................................................................................................55 ii LIST OF TABLES Table Page Table 1: Sample Descriptions ..............................................................................................5 Table 3-1. Previous Ferberite Data from The American Mineralogist Crystal Structure Database .............................................................................................................11 Table 3-2. Previous Hübnerite Data from The American Mineralogist Crystal Structure Database .............................................................................................................12 Tables 3-3. – 3-16. Sample and Crystal Data ...................................................................13 Table 3-17. Atomic Coordinates Equivalent Isotropic Atomic Displacement Parameters (Å2) .................................................................................................................20 Table 3-18. Bond Distance and Bond Valence Values ......................................................21 Table 3-19. Major Elemental Composition Analyzed by Agilent ICP-OES using external standards...............................................................................................................30 Tables 3-20. – 3-22. Trace Elemental Composition Analyzed by Varian 820 ICP-MS using standard addition ........................................................................................31 Tables 3-23. & 3-24. Largest P-XRD Peaks Including Reflection Intensity .....................36 iii LIST OF FIGURES Figure Page Figure 3-1. Composition versus Unit Cell Parameter a ..................................................... 24 Figure 3-2. Composition versus Unit Cell Parameter b ..................................................... 24 Figure 3-3. Composition versus Unit Cell Parameter c ..................................................... 25 Figure 3-4. Composition versus Unit Cell Parameter β .....................................................25 Figure 3-5. Composition versus Fe/Mn O1 Bond Distances .............................................27 Figure 3-6. Composition versus Fe/Mn O2 Bond Distances .............................................27 Figure 3-7. Composition versus Fe/Mn O2’ Bond Distances ............................................28 Figure 3-8. Wolframite Atomic Structure ..........................................................................29 Figure 3-9. Raman Spectra showing Raman Shift .............................................................37 Figure 3-10. All Chemical Data Cluster Analysis Dendrogram ........................................38 Figure 3-11. Major Elemental Data Cluster Analysis Dendrogram ..................................39 Figure 3-12. Trace Elemental Data Cluster Analysis Dendrogram ...................................39 Figure 3-13. SC-XRD Data Cluster Analysis Dendrogram ...............................................39 Figure 3-14. P-XRD Data Cluster Analysis Dendrogram .................................................40 Figure 3-15. Raman Cluster Analysis Dendrogram ...........................................................40 Figure 3-16. All Data Cluster Analysis Dendrogram ........................................................40 iv CHAPTER 1: INTRODUCTION In 2010, U.S. President Barack Obama signed the Dodd-Frank Wall Street Reform and Consumer Protection Act (hereafter Dodd-Frank) into Federal Law. The law is defined as “an Act to promote the financial stability of the United States by improving accountability and transparency in the financial system in order to protect consumers from abusive financial service practices…” (US Securities and Exchange Commission 2009). Title XV, Section 1502 (and to some extent,