The Preservation and Identification of Piñon Resins by GC‐MS in Pottery from the Western Great Basin

Gas chromatography — mass spectrometry analysis of a sherd from the Nevada Test Site revealed a high quantity of terpenes, including sesquiterpenoids and diterpenoids, demonstrating that piñon resins were prepared in the pot in prehistoric times. The presence of these biomarkers allowed for a very specific identification of the products prepared in the pot, a level of detail not often achieved in lipid residue analysis. That the terpenes are relatively unoxidized demonstrates that they are quite stable over long periods of time. The study also shows that sherds on the surface of archaeological sites can preserve lipids and terpenes and are amenable to organic residue analysis.     

BULK STABLE LIGHT ISOTOPIC RATIOS IN RECENT AND ARCHAEOLOGICAL RESINS: TOWARDS DETECTING THE TRANSPORT OF RESINS IN ANTIQUITY?*

We have applied and refined methods for the determination of bulk hydrogen, carbon and oxygen isotope ratios in modern and archaeological resins. The modern resins have a wide range of isotopic values and vary within the same tree, between individual trees, with species and location. For all isotopes measured, there is a general trend of increasing depletion of the heavier isotope with increasing altitude. There is also a linear trend between depletion of δD and δ¹³C values with increasing latitude; this trend is less clear for oxygen, but is related to the meteoric water line. Two case studies using archaeological resins known or suspected to have been transported in antiquity have been investigated to determine whether isotopic signatures can assist in pinpointing the geographical origin of the resin: Pistacia sp. resin from Canaanite amphorae imported into Egypt from known geographical locations in the eastern Mediterranean during the Late Bronze Age, and Roman amphorae sherds lined with Pinus sp. resin from sites ranging from Britain to the eastern Mediterranean. These results show separate groupings between the two resin types (pine/pistacia) and between the modern/archaeological resins. Some archaeological samples are distinct from the others and the modern resins show differences between geographical areas. However, there are no clear patterns relating the different Canaanite fabrics or the suggested manufacturing site of the Roman amphorae.     

CHEMICAL CHARACTERIZATION OF ANCIENT MESOAMERICAN ‘COPAL’ RESINS: PRELIMINARY RESULTS*

So‐called ‘copal’ resins from nine Aztec/Mixtec turquoise mosaics have been subject to analysis by gas chromatography – mass spectrometry to examine their higher terpenoid composition with a view to botanical identification. Botanical specimens and modern commercial ‘copal’ resins were analysed for reference. A range of botanical sources for the resins was identified, including pine, Protium and possibly Bursera. The data reinforce the ambiguity in the use of the term ‘copal’ and demonstrate the need for further work on characterization of ancient Bursera resins.     

SOUTHERN ASIA'S OLDEST INCENDIARY MISSILE?*

A small burnt ball was recovered in 1995 from the basal fills of a ditch surrounding the Bala Hisar, or High Fort, of Charsadda, Pakistan. Associated by Sir Mortimer Wheeler with the siege of the ancient site by Alexander the Great in 327 bce , the ditch forms part of the city's defensive circuit. Using geochemical and microscopic techniques (X‐ray diffraction, micro‐FTIR, SEM and GC–MS) the ball is identified as an artificial composite of mineral (mostly barite) and flammable resinous organic matter originating from conifers from the Podocarpaceae, Araucariaceae and Cupressaceae. The physical and chemical nature of the find suggests that the ball was ignited in a fire, although whether this was a deliberate or accidental occurrence is impossible to establish. The analytical data, combined with the archaeological context of the find, leads us to evaluate whether the find represents southern Asia's earliest incendiary missile.     

NUCLEAR MAGNETIC RESONANCE CHARACTERIZATION OF CRETACEOUS AMBER

Carbon-13 nuclear magnetic resonance spectra have been examined under high resolution conditions for 31 samples of fossil resin that have been dated to the Cretaceous period. Samples from Alaska, Canada, parts of the United States, Greenland, France, Switzerland, Lebanon, Jordan, and Israel have very similar spectra, consistent with a common, geographically dispersed palaeobotanical source. Samples within this large group exhibit a variation in spectral linewidth that is consistent with differences in sample age or maturity. A single Triassic sample from Bavaria shows the same spectral patterns but greater linewidths, indicating that it probably had a similar palaeobotanical source.     

THE CHARACTERIZATION OF PAINTS AND WATERPROOFING MATERIALS FROM THE SHIPWRECKS FOUND AT THE ARCHAEOLOGICAL SITE OF THE ETRUSCAN AND ROMAN HARBOUR OF PISA (ITALY)*

This work presents the results of a diagnostic survey on the shipwrecks from the archaeological site of the ancient harbour of San Rossore (Pisa, Italy). The original waterproofing, caulking and painting materials were characterized by Fourier transform infrared spectroscopy (FTIR), gas chromatography – mass spectrometry (GC–MS), energy‐dispersive X‐ray microanalysis (EDX) and X‐ray diffraction (XRD). The major constituents of the waterproofing and caulking materials detected on the planks were tricyclic abietanes showing a high degree of aromatization. These compounds are indicative of a pitch obtained from the wood of trees of the Pinaceae family. The analysis of the organic components of the paint samples revealed diterpenoid acids characteristic of Pinaceae resins together with linear long‐chain alcohols and fatty acids, highlighting the presence of beeswax. Noticeably, the characteristic odd carbon number alkanes that are normally present in beeswax were not detected. The EDX and XRD analyses showed that hematite, calcite, cerussite and kaolinite were employed as pigments to paint the ships’ hulls.     

THE STUDY OF NABATAEAN ORGANIC RESIDUES FROM MADÂ’IN SÂLIH,ANCIENT HEGRA,BY GAS CHROMATOGRAPHY – MASS SPECTROMETRY*

Four Nabataean samples collected in some of the monumental tombs of Madâ’in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa‐9(11),12‐dien‐3‐ol, ursa‐9(11),12‐dien‐3‐one, olean‐9(11),12‐dien‐3β‐ol, β‐amyrone, β‐amyrin, α‐amyrone, α‐amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium.     

DISTINGUISHING AMBER AND COPAL CLASSES BY PROTON MAGNETIC RESONANCE SPECTROSCOPY

Fossilized resin, or amber, has been examined from 120 worldwide sources by 1D and 2D proton magnetic resonance spectroscopy in solution. These spectra fall into five categories, corresponding to the classes already established by mass spectrometry and carbon‐13 magnetic resonance spectroscopy. The wide availability of this technique provides a straightforward method to classify amber rapidly and inexpensively.     

1H‐NMR AND 31P‐NMR CHARACTERIZATION OF THE LIPID FRACTION IN ARCHAEOLOGICAL OINTMENTS

Lipids are a broad group of naturally occurring molecules, which includes fats, oils, waxes, sterols, terpenes, fat‐soluble vitamins, monoglycerides, diglycerides, phospholipids and others. Lipids have been widely used in human history and they are often present in archaeological finds. In particular, in the field of medicine and cosmetics, lipids have been employed as base in the preparation of unguents, salves and balms. The characterization of these products and their degradation products induced by ageing is important for an understanding of the ancient pharmaceutical techniques and to assess the state of conservation. ¹H‐NMR and, for the first time, ³¹P‐NMR spectroscopy have been applied to the characterization of such compounds. By derivatization of the samples with 2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaphospholane, it is possible to recognize, quantify and evaluate the degradation degree of lipids in archaeological unguent samples. With this new approach, lipids have been recognized in 17th‐century archaeological ointments from the Aboca Museum. Moreover, severe hydrolysis and oxidation markers have been detected.