What is petroarchaeology?
Petroarchaeology, as I define it, is the application of petrology and petrography (defined above) to archaeology. Rocks are studied compositionally and/or mineralogically but with the goal of learning about human behavior and cultures in the past. Petrology and petrography involve the study of rocks and minerals, but the approaches and techniques can also be applied to archaeological materials other than lithic artifacts, including pottery and other ceramics, glass and faience, and metal artifacts and slag. I offer examples of typical petroarchaeological studies below.
How is "petroarchaeology" different from "lithic analysis"?
Lithic analysis typically refers to the study of stone artifacts based on their morphology, measurement of physical attributes, and other features (e.g., the presence of cortex) in order to determine manufacturing techniques. Petroarchaeology, on the other hand, takes a compositional or mineralogical approach to studying stone tools (both flaked and ground-stone tools) and other artifactual rocks (such as monumental or building stone and sculptures). As noted above, petroarchaeology can also involve ceramics, glass, metal artifacts, and slag.
How does "petroarchaeology" compare to "geoarchaeology" or "archaeological geology"?
Geoarchaeology, as I and others define it, is the application of geological theories, approaches, and techniques to address archaeological research questions, particularly when incorporated into the initial research design. Archaeological geology, as I and others define it, refers to using geological data, collected previously and independently, to address archaeological research questions. (I should note that there is some disagreement about these definitions and what exactly differentiates geoarchaeology and archaeological geology.) Geology, though, is a very broad field and includes environmental geology, geomorphology, oceanography, geochemistry, seismology, hydrology, sedimentology, pedology, and many other subfields. Petroarchaeology specifically involves the subfields of petrology and petrography, but I would assert petroarchaeology is a subset of both geoarchaeology and archaeological geology, usually the former.
Is petroarchaeology part of archaeological science or archaeometry?
Archaeological science usually refers to the use of the natural and biological sciences in archaeology; this includes biology, chemistry, physics, geology, geophysics, anatomy, and other scientific fields. Naturally the use of petrology in archaeology falls under classification of archaeological science. Is it archaeometry? It depends on what one calls "archaeometry." The word itself means "measuring the ancient," and that could describe petroarchaeology. Commonly, though, archaeometry is considered to involve the use of modern analytical techniques, such as mass spectrometry and neutron activation analysis. Petroarchaeology does not, however, necessarily involve such analytical techniques (please see a discussion on "the tools of petroarchaeology" below), so one cannot simply state it is or is not archaeometry.
What are examples of typical petroarchaeological studies?
Petroarchaeological studies will often involve observing the mineral structure of stone artifacts (including flaked or chipped stone, monumental or building stone, and sculptures) in an effort to determine their geological source. Ceramics can also be examined to identify their components in order to investigate production and technology. Similarly ancient glass can be characterized to identify, for example, the ingredients used to add color. Techniques used to make glass red, for instance, can vary greatly among different cultures. Examination of slag waste and metal artifacts themselves can reveal the details of a culture's metallurgical technology and traditions. If you would like to learn more about such studies, suggested books and articles, including introductory readings, can be found further down this page.
What are the tools of petroarchaeology?
The tools are the same as those used in petrography. Petrographic observations can start in the field with a hand lens, a loupe, or the naked eye. A petrographic microscope allows for identification of minerals in thin section and observation of the micro-texture and structure of the specimen. An electron microprobe, also known as an electron probe microanalyzer, combines scanning electron microscopy with chemical analysis on a micro-scale. An x-ray diffractometer can also identify the minerals within a specimen based on their crystalline structures. Other techniques can also be used to collect specific information: Raman spectrometry, electron backscatter diffraction, mass spectrometry, etc.
How is petrography used in ceramic analysis?
Petrographic analysis can identify ceramics' mineral components, including the clay itself, naturally occurring inclusions in the clay, and rock fragments (temper) added by the makers. Such studies can reveal how the makers selected and used local versus non-local geological resources, whether a particular ware was produced locally or came from a distant locale, and how the ware was manufactured. All of this information can offer come insight into settlement patterns, mobility, craft specialization, inter-group social contacts, and trade and exchange networks.
How can this approach be used to study glass and metal artifacts?
The same rules that describe crystal formation in rocks also apply to glasses and metals, so there are minerals as well as amorphous melts in these types of materials too. Among the best resources on this subject is the book The Science and Archaeology of Materials by Julian Henderson, an expert in archaeological glass. His chapter on glass is, not surprisingly, probably the best in the book, but there are also chapters on ceramics, metal, and stone. For a book on metals, I suggest reading Peter Schmidt's Iron Technology in East Africa: Symbolism, Science, and Archaeology. Another book that covers glass, metal, and ceramics is Sheridan Bowman's Science and the Past.
Is "petroarchaeology" just a term you made up?
When I started using "petroarchaeology" a few years ago in order to describe what I do, I had never heard anyone use that term before. When I did a Google search for the word, though, I learned that a few other researchers, especially in eastern European countries, were using "petroarchaeology" to describe their research. For example, the Poznań Archaeological Museum in Poland created a joint archaeological-petrographic research program in 1971 and was using the term as early as 1974; Jindrich Stelcl and Jaroslav Malina in Czechoslovakia wrote the book Základy Petroarcheologie (Foundations of Petroarchaeology) in 1975; a conference on petroarchaeology was held in Poland in 1980 and in Bulgaria four years later; Katalin Takács-Biró at the Hungarian Geological Institute has been using the term since the 1980s; Piotr Chachlikowski at the Institute of Prehistory in Poland has taught a class on petroarchaeology; and the Mineralogical Society of Poland held their conference in 2003 with a session on petroarchaeology. More people are starting to recognize the term, but its use is not very widespread outside eastern Europe -- and I'm not really sure why.
Is the term "petroarchaeology" sometimes misunderstood?
Yes, sometimes people hear "petroarchaeology" and think of oil, as in petroleum. They suspect that I either (1) study ancient uses of oil or (2) excavate tar pits. When one considers the derivation of the word "petroleum" from its Greek origins, petra means "rock" while it actually is oleum that means "oil," so that it literally means "rock oil."
Have you come across the terms "archaeopetrology" or "archaeopetrography" instead?
I've seen "archaeopetrology" used twice: on the website of a private analytical company and in the dissertation title of an archaeologist at the University of Washington. I've heard that "archaeopetrography" was once used in a lecture title at a Hungarian archaeological conference. The issue with these terms is that archaeo-, meaning "ancient," modifies the root word, either petrology or petrography. Consequently, "archaeopetrology" should mean "ancient petrology," as in ancient research into the origin, composition, and structure of rocks. Peri Lithon (On Stones) by the Greek scholar Theophrastus (372-287 BCE), a protege of Aristotle, is an example of archaeopetrology. This interpretation is consistent with the terms archaeomineralogy and archaeometallurgy. George "Rip" Rapp coined the term archaeomineralogy in his book with that title. It is not a book about using modern mineralogy to answer archaeological questions. Instead, it is a book about the uses of and notions about minerals in the past, from prehistory until the 17th century. Likewise, archaeometallurgy is the study of past metallurgical knowledge and techniques, from ancient to historical times. Therefore, archaeopetrology and archaeopetrography, though valid areas of study, are very different from petroarchaeology.
Suggested Introductory Readings:
Clough, T. H. McK. and A.R. Woolley (1985) Petrography and Stone Implements. World Archaeology 17(1):90-100.
Garrison, E.G. (2003) Chapter 6: Petrography for Archaeological Geology. In Techniques in Archaeological Geology. Springer-Verlage, Berlin. pp. 153-206.
Kempe, D.R.C. and Harvey, A.P. (editors) (1983) The Petrology of Archaeological Artefacts, Clarendon Press.
Kempe, D.R.C. and Harvey, A.P. (1989) The Petrology of Archaeological Artefacts. In Scientific Analysis in Archaeology, Julian Henderson, editor. Oxford University Committee for Archaeology, Monograph 19.
Select Further Readings:
Andrefsky, W. (1998) Chapter 3: Lithic Raw Materials. Lithics: Macroscopic Approaches to Analysis. Cambridge Manuals in Archaeology. Cambridge University Press, pp. 40-58.
Bareis, Charles J. and James Warren Porter (1965) Megascopic and Petrographic Analyses of a Foreign Pottery Vessel from the Cahokia Site. American Antiquity 31(1):95-101.
Berry, R.W. (1969) Cylinder Seal Mineralogy and Petrology. American Journal of Archaeology 73:67-69.
Betts, I.M. (1991) Thin section and neutron activation analysis of brick and tile from York and surrounding areas. Recent Developments in Ceramic Petrology. British Museum Occasional Paper 81:39-55.
Brown, D.H. and Vince, A.G. (1984) Petrological Aspects: the Medieval Pottery of Exeter under the Microscope. Medieval and Post-Medieval Finds from Exeter 1971-1981. Exeter Archaeology Reports 3:32-34.
Catt, J.A. and A.H. Weir (1976) The Study of Archaeologically Important Sediments by Petrographic Techniques. In Geoarchaeology: Earth Science and the Past, D.A. Davidson and M.L. Shackley (editors). Duckworth, pp. 65-92.
Clark, W.W. (1994) New Light on Old Stones: Quarries, Monuments, and Sculpture in Medieval France. Gesta 33:3-9.
Garner, M. and Williams, D.F. (1981) Petrological analysis of medieval floor-tiles from Hailes Abbey, Glos. Ancient Monuments Laboratory Report 3444.
Hegmon, M., M.C. Nelson, and M.J. Ennes (2000) Corrugated Pottery, Technological Style, and Population Movement in the Mimbres Region of the American Southwest. Journal of Anthropological Research 56:217-240.
Herz, N. and E.G. Garrison (1998) Chapter 10: Archaeological Materials: Rocks and Minerals. Geological Methods for Archaeology. Oxford University Press, pp. 193-211.
Hughes, M.J., Cherry, J., Freestone, I.C., and Lease, M. (1982) Neutron activated analysis and petrology of medieval English decorated floor tiles from the Midlands. Current Research in Ceramics: Thin Section Studies, British Museum Occasional Paper 32:113-122.
Hunt, P.N. and D.R. Griffiths (1989) Optical Petrology in the Field. World Archaeology 21(1):165-172.
Kamilli, D.C. and A. Steinberg (1985) New Approaches to Mineral Analysis of Ancient Ceramics. In Archaeological Geology, George Rapp and John A. Gifford (editors). Yale University Press. pp. 313-330.
Luedtke, B.E. (1992) An Archaeologist's Guide to Chert and Flint. Archaeological Research Tools 7. Institute of Archaeology, University of California, Los Angeles.
Maggetti, M. and B. Messiga, editors (2006) Geomaterials in Cultural Heritage. Geological Society, London.
Mason, Owen K. and Jean S. Aigner (1987) Petrographic Analysis of Basalt Artifacts from Three Aleutian Sites. American Antiquity 52(3):595-607.
Mitchell, T. and A. Middleton (2002) The Stones Used in the Assyrian Sculptures. Journal of Cuneiform Studies 54:93-8.
Peacock, D.P.S. (1980) The Roman Millstone Trade: A Petrological Sketch. World Archaeology 12(1):43-53.
Rapp, G. (2002) Archaeomineralogy. Springer-Verlag, Berlin.
Rapp, G. and C.L. Hill (2006) Chapter 7: Raw Materials and Resources. Geoarchaeology: The Earth-Science Approach to Archaeological Interpretation, Second Edition. Yale University Press, pp. 195-221.
Reedy, C.L. (1994) Thin-Section Petrography in Studies of Cultural Materials. Journal of the American Institute for Conservation 33:115-129.
Rosenfeld, A. (1965) The Inorganic Raw Materials of Antiquity. Weidenfeld and Nicolson, London.
Shackley, M.S. (1988) Sources of Archaeological Obsidian in the Southwest: An Archaeological, Petrological, and Geochemical Study. American Antiquity 53(4):752-772.
Shackley, M.S. (2005) Obsidian: Geology and Archaeology in the North American Southwest. University of Arizona Press.
Shotton, F.W. (1969) Petrological Examination. In Science in Archaeology: A Survey of Progress and Research, D. Brothwell and E. Higgs (editors). Thames and Hudson, London, pp. 571-577.
Stoltman, J.B. (1989) A Quantitative Approach to the Petrographic Analysis of Ceramic Thin Sections. American Antiquity 54(1):147-160.
Stoltman, J.B. (1991) Ceramic Petrography as a Technique for Documenting Cultural Interaction: An Example from the Upper Mississippi Valley. American Antiquity 56(1):103-120.
Stoltman, J.B. (2001) Chapter 11: The Role of Petrography in the Study of Archaeological Ceramics. In Earth Sciences and Archaeology, P. Goldberg, V.T. Holliday, and C.R. Ferring (editors). Kluwer Academic, pp. 297-326.
Swanson, S.E., Steponaitis, V.P., Wheeler, G. and Johnson, J.S. (2005) Mineralogy and petrology of palette stones from Etowah Mounds, Georgia. Geological Society of America, Annual Meeting Abstracts 37:47.
Turner, A.V., Swanson, S.E., and Roden, M.F. (1998) Mineralogic control on archaeological soapstone bowl manufacture. Geological Society of America, Annual Meeting Abstracts 30:63-64.
Turner, A.V. and Swanson, S.E. (1998) A mineralogical and geochemical comparison of two Native American soapstone quarries. Geological Society of America, Annual Meeting Abstracts 30:A17.
Vince, A.G. (1994) Gloucester Blackfriars: Petrological Examination of the Medieval Floor Tiles. CLAU Reports 187.
Vince, A.G. (1995) The Petrology of the Goodrich Castle Floor Tiles. CLAU Archaeological Reports 182.
Wagner, E. and C. Schubert (1972) Pre-Hispanic Workshop of Serpentinite Artifacts, Venezuelan Andes, and Possible Raw Material Source. Science 175:888-890.
Wallis, F.S. (1963) Petrological Examination. In The Scientist and Archaeology, E. Pyddoke (editor), pp 80-100.
Whitbread, Ian K. (1995) Greek Transport Amphorae: A Petrological and Archaeological Study. Fitch Laboratory Occasional Paper 4.
Williams, D.F. (1980) Petrological analysis of post-medieval pottery and tile from Oxfordshire. Ancient Monuments Laboratory Report 3015.
Williams, D.F. (1982) Petrological analysis of pottery and tiles from Exeter. Ancient Monuments Laboratory Report 3652.
Williams, D.F. (1990) Petrological examination of medieval pottery and tiles from Haughmond. Shropshire, Ancient Monuments Laboratory Report 65/90.
Wilson, L. (1988) Petrography of the Lower Palaeolithic Tool Assemblage of the Caune de l'Arago (France). World Archaeology 19(3):376-387.
Xenophontos, C. (1991) Picrolite, Its Nature, Provenance, and Possible Distribution Patterns in the Chalcolithic Period of Cyprus. Bulletin of the American Schools of Oriental Research 282/283:127-138.
