pXRF analysis of medieval and modern ceramics from Erbray (France)

<p>This dataset contains analyses of 60 ceramic samples from Les Landelles (Erbray, Loire-Atlantique, France). The chemical composition of the samples was obtained by portable X-ray fluorescence spectrometry (pXRF).</p> <p><strong>Method</strong></p> <p>The outer surfaces of all the samples were mechanically removed prior to analysis.</p> <p>The samples were heated to 950&deg;C for one hour after 24h drying at 50&deg;C, weighted for LOI calculation and ground in a tungsten carbide mortar. Measurements were made on pelletized powders.</p> <p>Measurements were carried out on powders placed in sample holders, through a Mylar film.</p> <p>A Vanta VCR C-series portable X-ray fluorescence spectrometer (Olympus) was used on a laboratory bench with a beam diameter of 10 mm. The spectrometer is equipped with a 4W, 40kV max, 200 &micro;A max X-ray tube (Rh anode) and a silicon drift detector (SDD). For each analysis, the instrument was operated alternately at low energy (10 keV) for 90 s to quantify light elements and at high energy (40 keV) for 90 s to quantify heavy elements. No vacuum or helium flow was used. Analytical repeatability, accuracy and precision were checked using an in-house obsidian standard.</p> <p>Using the GeoChem internal calibration, 15 elements were quantified: Al, Si, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Pb.</p> <p>The files beamspectra.csv and chemistry.csv are the export files as produced by the instrument.</p> <p>The file erbray.csv contains all chemical compositions (only chemical elements for which measurements are considered reliable are retained), with the following columns:</p> <ul> <li><em>sample</em>: sample reference.</li> <li><em>laboratory</em>: analysis laboratory.</li> <li><em>date</em>: date of the analysis.</li> <li><em>group</em>: technical group.</li> <li><em>material</em>: type of material.</li> <li><em>stratigraphy</em>: stratigraphic unit.</li> <li><em>comments</em>: extra information.</li> <li><em>LOI</em>: loss on ignition (percent).</li> <li><em>Al, Si, K, Ca, Ti, Cr, Fe, Rb, Sr, Zr, Pb</em>: amounts and corresponding uncertainties (ppm).</li> </ul>