MINERALOGY AND MINERAL CHEMISTRY OF SOUTHEASTERN PIEDMONT SOAPSTONES: IMPLICATIONS FOR SOURCING PREHISTORIC SOAPSTONE ARTIFACTS by NICHOLAS CYRIL RADKO (Under the direction of Samuel E. Swanson) ABSTRACT Soapstone is a soft, carvable metamorphic rock of ultramafic protolith that has been quarried for millennia by cultures around the globe to be fashioned into functional, decorative, and ritual objects. Archaeologists have long sought a methodology to reliably source soapstone artifacts to their geologic origin in order to better understand routes and mechanisms of exchange. This study uses traditional geologic methods to characterize prehistoric soapstone quarries in the Piedmont of the southeastern U.S. A combination of modal mineralogy and mineral chemistry data has been successful in uniquely characterizing three Late Archaic quarries—two from Soapstone Ridge, GA and one from the Hammett Grove Meta-igneous Suite, SC. A total of 10 Late Archaic soapstone vessel sherds from the Ocmulgee, Oconee, and Satilla drainages in the Georgia Coastal Plain were also analyzed for comparison. Modal mineralogy, low-Ca amphibole and ilmenite compositions proved most useful in distinguishing samples. INDEX WORDS: Soapstone, Steatite, Mineralogy, Microprobe, Late Archaic MINERALOGY AND MINERAL CHEMISTRY OF SOUTHEASTERN PIEDMONT SOAPSTONES: IMPLICATIONS FOR SOURCING PREHISTORIC SOAPSTONE ARTIFACTS by NICHOLAS CYRIL RADKO B.S., The University of Virginia, 2008 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2011 © 2011 Nicholas Cyril Radko All Rights Reserved MINERALOGY AND MINERAL CHEMISTRY OF SOUTHEASTERN PIEDMONT SOAPSTONES: IMPLICATIONS FOR SOURCING PREHISTORIC SOAPSTONE ARTIFACTS by NICHOLAS CYRIL RADKO Major Professor: Sam Swanson Committee: Ervan Garrison Paul A. Schroeder Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia May 2011 ACKNOWLEGEMENTS First and foremost, I would like to extend my most sincere thanks to Dr. Sam Swanson. His constant efforts to guide me through my research and provide insightful and constructive feedback have, without a doubt, been the most reliable and important source of encouragement (as well as assistance) throughout my thesis work. Dr. Swanson is the most dedicated teacher and advisor that I have encountered in my academic career, and his selfless commitment to his students, graduate and undergraduate, has never failed to amaze and inspire me. Next I would like to acknowledge and thank my committee members, Dr. Ervan Garrison and Dr. Paul Schroeder. Their instruction in and outside the classroom has been invaluable to me during my time here at UGA, I am much obliged to them for all of their help and support. I would be remiss to overlook the assistance and patience of Chris Fleisher, who’s guidance in the probe lab was irreplaceable. The independence I was afforded instilled much confidence. Staying in the basement, I must thank all of my graduate student colleagues for making the academic and extracurricular pursuits comprising my life for the past two years most enjoyable. In particular, I’d like to acknowledge those students who matriculated in the Fall of 2009. Finally, I want to thank the Department of Geology, not only for funding my project through the Miriam Watts-Wheeler Graduate Studies Student Fund, but also for providing so many wonderful opportunities and resources, not the least of which has been the chance to teach geology during my tenure as a student and beyond. ! "#! TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ...........................................................................................................iv LIST OF FIGURES.......................................................................................................................vii CHAPTER 1 INTRODUCTION..........................................................................................................1 2 GEOLOGY.....................................................................................................................3 ORIGIN OF SOAPSTONE....................................................................................3 SOAPSTONE IN THE SOUTHEAST...................................................................4 3 ARCHAEOLOGY........................................................................................................11 SOAPSTONE NOMENCLATURE.....................................................................11 SOURCING STUDIES ........................................................................................12 SOAPSTONE AND SOUTHEASTERN PREHISTORY ...................................14 HISTORY OF SOAPSTONE RESEARCH.........................................................16 STUDY QUARRIES............................................................................................19 4 METHODS...................................................................................................................30 SAMPLE SELECTION AND PREPARATION .................................................30 MODAL MINERALOGY....................................................................................32 ELECTRON MICROPROBE ANALYSIS (EMPA)...........................................32 X-RAY DIFFRACTION (XRD)..........................................................................34 5 RESULTS.....................................................................................................................36 ! 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MODAL MINERALOGY....................................................................................36 MINERAL CHEMISTRY....................................................................................40 X-RAY DIFFRACTION (XRD)..........................................................................58 6 DISCUSSION...............................................................................................................61 QUARRIES ..........................................................................................................61 ARTIFACTS ........................................................................................................63 7 CONCLUSIONS ..........................................................................................................67 REFERENCES CITED .................................................................................................................69 APPENDICES...............................................................................................................................74 A MINERALOGY AND X-RAY DIFFRACTION (XRD) ...........................................75 A.1 MODAL MINERALOGY.............................................................................76 A.2 MINERALOGY ............................................................................................77 A.3 X-RAY DIFFRACTION (XRD) ...................................................................81 A.4 BULK CHEMISTRY ....................................................................................89 B MINERAL CHEMISTRY ...........................................................................................90 B.1 - CHLORITE .................................................................................................91 B.2 - CALCIC AMPHIBOLE ............................................................................116 B.3 - NON-CALCIC AMPHIBOLE ..................................................................152 B.4 - MAGNETITE............................................................................................184 B.5 - ILMENITE ................................................................................................224 B.6 - RUTILE.....................................................................................................248 B.7 - TALC.........................................................................................................256 ! 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LIST OF FIGURES Page Figure 1: Soapstone deposits in the Southeast with study quarry locations....................................6 Figure 2: Location and general geology of SSR .............................................................................8 Figure 3: Location and general geology of HGMS .........................................................................9 Figure 4 a: Bowl blank at PA with the author for scale.........................................................20 b: Bowl scar at PA...................................................................................................20 c: Unfinished vessel at PA.......................................................................................21 Figure 5: Detail of PA (38Sp12) study area ..................................................................................21 Figure 6: Regional watersheds and sample locations....................................................................23 Figure 7: SSR showing LO (9Da139) and CW (9Da248).............................................................24 Figure 8: LO (9Da139) and CW (9Da248) quarries .....................................................................25 Figure 9: Provenience of LO samples ...........................................................................................27 Figure 10: CW quarry site (9Da248a) ...........................................................................................29 Figure 11 a: Ternary diagram of talc, chlorite, and amphibole modes