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

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).

Method

The outer surfaces of all the samples were mechanically removed prior to analysis.

The samples were heated to 950°C for one hour after 24h drying at 50°C, weighted for LOI calculation and ground in a tungsten carbide mortar. Measurements were made on pelletized powders.

Measurements were carried out on powders placed in sample holders, through a Mylar film.

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 µA 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.

Using the GeoChem internal calibration, 15 elements were quantified: Al, Si, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Pb.

The files beamspectra.csv and chemistry.csv are the export files as produced by the instrument.

The file erbray.csv contains all chemical compositions (only chemical elements for which measurements are considered reliable are retained), with the following columns:

sample: sample reference.

laboratory: analysis laboratory.

date: date of the analysis.

group: technical group.

material: type of material.

stratigraphy: stratigraphic unit.

comments: extra information.

LOI: loss on ignition (percent).

Al, Si, K, Ca, Ti, Cr, Fe, Rb, Sr, Zr, Pb: amounts and corresponding uncertainties (ppm).