GEOLOGIC PERSPECTIVE IN CLASSICAL MARBLE PROVENANCE STUDIES: THE EVOLVING RELATIONSHIP OF THE GEOLOGIST AND THE ARCHAEOLOGIST OVER 140 YEARS OF GEOCHEMICAL, PETROGRAPHIC, AND STRUCTURAL ANALYSIS

Over the past 140+ years, the Classical archaeologist has sought to find an accurate method to characterize the provenance of marble artifacts. Finding provenance of Classical marble involves sourcing material to the location where it was originally quarried. Accurate provenance can distinguish an artifact from a forgery, help to date the creation of the work, and provide information on ancient economic geology processes. Prior to the late 19^th century, this was a task left only to the art historian and archaeologist. Methodology was based solely on visual analysis of artifact marble. Problems were evident in the case of white or grey marbles, which are nearly impossible to distinguish from one another with the naked eye. Marble, loosely defined as a metamorphic rock with a protolith of limestone or dolomite, is a geologic material and can be analyzed as such via geochemistry and petrography. In almost every case since the late 19^th century this has involved the work of a geologist. With the increased use of thin section analysis after the mid-1800s, there appeared to be a way for the marble to be sourced petrographically. This was not quite enough in many instances, however. In the late 1960s isotopic analysis (¹³C/¹²C and ¹⁸O/¹⁶O) and trace element geochemistry were used to typify samples and progress further towards accurate distinctions. Issues with quarry heterogeneity and sample size soon became evident. The geologic history of each marble quarry site must be understood in order to begin to distinguish samples from one another. Even as quantitative analysis of marble continues to improve, it appears that provenance may be more complex than previously thought. There is still no single variable that characterizes all marble types uniquely, making a multivariate approach necessary. This study explores the integrated relationship of the geoscientist and the Classical archaeologist from historic to present time, investigates several case studies, and seeks to apply this knowledge to the expanding field of archaeological geology. This is the first study to put together the entire timeline of research from ~1870 to present. In the transfer of the original visual analysis to the geologist’s quantitative approach, we continue to ask what has been gained, and what may have been lost in the process.