Raman spectroscopic analysis of human remains from a seventh century cist burial on Anglesey, UK.

Specimens from human remains exhibiting unusual preservation excavated from a seventh century stone cist burial at Towyn y Capel in Anglesey, UK, have been analysed using Raman spectroscopy with near-infrared laser excitation at 1,064 and 785 nm. Specimens of hair and bone provided evidence for severe degradation and microbial colonisation. The deposits within the stone cist showed that some microbially mediated compounds had been formed. Analysis of crystals found at the interface between the hair and the skeletal neck vertebrae revealed a mixture of newberyite and haematite, associated with decomposition products of the hair and bone. An interesting differential degradation was noted in the specimens analysed which could be related to the air-void and the presence of plant root inclusions into the stone cist. This is the first time that Raman spectroscopy has been used in the forensic archaeological evaluation of burial remains in complex and dynamic environments.

Life in the sabkha: Raman spectroscopy of halotrophic extremophiles of relevance to planetary exploration.

The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.

Anatase--a pigment in ancient artwork or a modern usurper?

Fragments of wall-paintings from Roman villas in Easton Maudit, which date from ca 150 AD have been studied by Raman spectroscopy. An intact ancient Roman paint pot discovered in the remains of a villa in Castor, Cambridgeshire, still containing a mixture of white and red pigment was also analysed and the pigments identified as haematite and anatase. The discovery of anatase in the intact artist's paint pot, particularly, and also on fragments of broken paint pots from the Easton Maudit villa site, is a unique contribution to current knowledge of ancient European pigment history, because the presence of this mineral has not hitherto been recognised fully in an ancient artist's palette. The relative spectral response of anatase and haematite in the Raman data is compared with that of anatase and other red pigments such as minium, cinnabar, and litharge.

Ancient biodeterioration: an FT-Raman spectroscopic study of mammoth and elephant ivory.

Raman spectra of mammoth ivory specimens have been recorded using near-infrared excitation, and comparisons made with modern Asian and African elephant ivories. Whereas the most ancient mammoth ivory (60-65 ky) showed no evidence for an organic collagen component, more recent samples of mammoth ivory indicated that some preservation had occurred, although with biodeterioration of the protein structure exhibited by the amide I and III bands in the 1200-1700 cm(-1) region of the Raman spectrum. The consequent difficulties encountered when applying chemometrics methods to ancient ivory analysis (which are successful for modern specimens) are noted. In the most ancient mammoth ivory specimens, which are extensively fragmented, evidence of mineralization is seen, with the production of gypsum, calcite and limonite; Raman microscopic analysis of crystalline material inside the fissures of the mammoth ivory shows the presence of gypsum as well as cyanobacterial colonisation. The application of Raman spectroscopy to the nondestructive analysis of archaeological materials in order to gain information of relevance to their preservation or restoration is highlighted.