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Alkali feldspar is routinely used in retrospective dosimetry using luminescence methods. However there is a signal loss over time, termed ‘anomalous fading’, which results in age underestimation if uncorrected. Although significant improvements have been made in recent years, luminescence dating of feldspars remains challenging. This paper investigates the relationships between chemistry, structural state and the scale of exsolution with thermoluminescence (TL) emission spectra and infrared stimulated luminescence (IRSL) fading rates. We measure TL emission spectra, where possible linking the recombination site to physical features of the feldspar crystals. We show that fading rates are lowest in ordered end-member Na- and K-feldspars but significantly greater in disordered end-members, showing that Al–Si order influences fading. As well as having very low fading rates, ordered end-member samples have distinctive TL emission spectra, with the yellow-green emission dominant, while all other samples have a dominant blue emission. Perthite, i.e. exsolved members of the (Na,K)-feldspar solid solution, show greater fading than disordered end-members and fading is greatest in semi-coherent macroperthite. We propose that the state of Al–Si-order, and the occurrence of defects and dislocations at the perthite lamellar interfaces influence anomalous fading rates in feldspar.

This paper presents the results of analytical work which aimed to explore potential\ud sources for the lime mortar used in the Hadrianic fort baths and a third-century\ud repair to Hadrian's Wall at Wallsend, UK. It is generally assumed that quick lime for\ud mortar is produced close to the source, however, as yet, no archaeological evidence\ud of kilns has been found in the Wallsend area. After extensive analysis the mortars\ud were found to be very different in characteristics and suggest variable sources for\ud the quarried limestone and for the aggregates used to manufacture the mortar.\ud Precedence exists in other locations for quicklime to be sourced from kilns set at\ud some considerable distance from Roman construction sites. It is only at\ud Housesteads and Vindolanda, sited close to Carboniferous Limestone outcrops, that\ud Roman lime kilns have been discovered to date. Therefore the investigation\ud included a number of potential sources in the vicinity of Housesteads as well as\ud Permian limestones at Trow Point which is geographically the closest source of\ud limestone. Results suggest that Carboniferous limestone was the most likely source\ud for some of the mortars analysed which may suggest that areas for lime production\ud are less numerous than previously thought and may even have been concentrated\ud around one area.

Glasses with nominal molar composition 20B2O3 – (80-x)Bi2O3 – xFe2O3 (where x = 0–40) were successfully prepared by melt-quenching. These glasses were characterised by multiple techniques including density, X-ray diffraction (XRD), X-Ray fluorescence (XRF), Raman, FT-IR and Mossbauer spectroscopies, dilatometry and differential thermal analysis (DTA). Partial replacement of Bi2O3 by Fe2O3 leads to decreasing density and molar volume and a substantial increase in thermal stability, as measured by several parameters, with maximum improvements achieved when x = 10-20. These improvements are accompanied by modest increases in dilatometric softening point. FT-IR and Raman spectra confirm the presence of BO3 and BiO6 structural units in all glasses, with glass structure apparently little affected by Fe2O3. Mossbauer spectroscopy confirms that iron is present partly as 4-fold coordinated Fe3+ in all glasses, with some 5- and / or 6- coordinated Fe3+ sites also present.

The focus of this study consists of examining how simultaneous SR-XRD and electrochemical measurements can provide information on the effectiveness of stabilization and storage treatments of copper artefacts in aqueous solution. The electrochemical cell used here was designed for in situ, time resolved SR-XRD studies of corrosion and inhibition studies on cultural heritage materials. Key objectives of the new cell were to monitor corrosion layers on alloys with realistic metallographic structures and to obtain co-incident, time resolved, electrochemical data such as reduction measurements, oxidation measurements and corrosion potential (Ecorr) measurements. Here we present some early results from the cell. Firstly, a correlated SR-XRD and corrosion potential (Ecorr) study of the reduction of nantokite during storage in sodium sesquicarbonate, which shows that the surface chemistry continues to change after Ecorr has stabilized. Secondly, the use of X-ray data to identify specific changes occurring as a function of potential in the forced reduction of a more complex system. Keywords: Spectroelectrochemistry, SR-XRD, Corrosion, Copper, Cultural heritage, Conservation