X-Ray Fluorescence Spectrometry and Its Applications to Archaeology

Mary Kate Donais, David B. George

• Publisher: Momentum Press
• Year: 2018
• Print ISBN: 9781944749293
• eBook ISBN: 9781944749309
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

This book serves as a practical guide for applications of X-ray fluorescence spectrometry, a nondestructive elemental analysis technique, to the study and understanding of archaeology. Descriptions of XRF theory and instrumentation and an introduction to field applications and practical aspects of archaeology provide new users to XRF and/or new to archaeology with a solid foundation on which to base further study. Considering recent trends within field archaeology, information specific to portable instrumentation also is provided. Discussions of qualitative and quantitative approaches and applications of statistical methods relate back to types of archaeological questions answerable through XRF analysis. Numerous examples, figures, and spectra from the authors' field work are provided including chapters specific to pigments, ceramics, glass, construction materials, and metallurgical materials.

CHAPTER 6

Pigments

6.1 Background

Pigments are used on or in many archaeological artifacts and materials including fresco, ceramics, wood, stone, glass, and architectural terracotta. The chemical characterization of pigments is quite common within cultural heritage research, and it can be applied across historic periods and into modern times. There is also a considerable overlap between the pigments discussed in this chapter and the characterization of ceramics (Chapter 7) and glass (Chapter 8). The focus of this chapter is on pigments found on fresco and architectural terracotta.

XRF, as noted in the first chapter, is not an effective tool in detection of organic compounds because it does not detect the lighter elements, including carbon, of which organic compounds predominantly consist. Organic pigments therefore produce little to no detectable XRF signal. Mineral-based pigments, on the other hand, often contain metals easily detected via XRF analysis. In addition, a number of pigments have both natural and synthetic forms or only exist in a synthetic form. Synthetic pigments were often developed later in history to provide a more reliable pigment source and/or a higher purity product. The date of development of synthetic pigments is often documented, so the presence of one of these pigments on a cultural heritage object can make confident determination of that object’s age possible.

A table summarizing information for pigments used within archaeology is provided in Table 6.1 (Burgio and Clark 2001; Rapp 2009; Douma 2008; Berke 2002; Feller 1986; Roy 1993; Fitzhugh 1997; Berrie 2007). Many of the pigments presented in the table, such as the ochres and green earth, are commonly found on archaeological artifacts, while others such as lapis lazuli are considered valuable and rare.

The four volume Artists’ Pigments: A Handbook of Their History and Characteristics is a tremendous resource for anyone wanting both the historic and chemical information specific to each pigment in a highly organized and referenced format (Feller 1986; Roy 1993; Fitzhugh 1997; Berrie 2007). The chemical formula, name(s), and origin for each pigment in Table 6.1 are listed by color. Where possible, the date or time period of origin and use is provided for synthetic pigments.

Table 6.1. Summary of pigments
Color	Pigment	Chemical Formula	Name(s)	Origin
White	Titanium white Chalk Gypsum Huntite Lead white	TiO2 CaCO3 CaSO4·2H2O Mg3Ca(CO3)4 2PbCO3·Pb(OH)2	Titanium dioxide, rutile, anatase Calcium carbonate, calcite Calcium sulfate dihydrate Magnesium calcium carbonate Basic lead(II) carbonate, ­hydrocerussite	Mineral/Synthetic (1923) Mineral Mineral Mineral Mineral/Synthetic (pre-500 BCE)
Blue	Azurite Egyptian blue Han blue Indigo Lazurite Verdigris (basic)1 Verdigris ­(neutral)1	2CuCO3·Cu(OH)2 CaCuSi4O10 BaCuSi4O1...

Table of contents

• cover
• halftitle
• title
• copyright
• Dedication
• abstract
• contents
• List of Figure
• List of tables
• Preface
• Ack
• 01_Chapter 01
• 02_Chapter 02
• 03_Chapter 03
• 04_Chapter 04
• 05_Chapter 05
• 06_Chapter 06
• 07_Chapter 07
• 08_Chapter 08
• 09_Chapter 09
• 10_Chapter 10
• 11_Summary
• 12_About the author
• 13_Index