I have ~5mm thick potsherds which are of archaeological importance. I want to date them using OSL. What steps should I follow during sample preparations and after sample preparation should I target feldspar or quartz or polymineral?
Thermoluminescence (TL) dating is given preference over optically stimulated luminescence (OSL) for the
archeological application.You can use SAR protocol for both quartz (blue light) potassium feldspar (infrared light).
https://www.aber.ac.uk/en/media/departmental/dges/pdf/english_heritage_luminescence_dating.pdf
A few things to note are :-
1) The sherd thickness is near the minimum to achieve a completely internal beta microdosimetry.For this the outer 2-3 mm would normally be removed, and both dose and dose rate measurements performed on the interior portions.
2) If this is not already too late the sherds should be double bagged and sealed, unwashed, from the excavation site, together with detailed records (photographs and sketches) of the materials within 30-50 cm of the find location. Subsamples of the materials in the categories should be retained. The reason for this is to allow reconstruction of the external gamma dose rates applicable to the excavation site. Typically this might account for about 30% of the total dose rate. If it is too late, then some information will be needed of the local hydrology to enable reasonable reconstruction of water content history.
3) Also note the geographical coordinates (longitude, latitude, altitude and overburden depth to surface) so that cosmic ray dose rates can be modelled
4) I agree that TL has some advantages for heated materials such as ceramics, but under appropriate conditions OSL may also be useful. There are OSL signal components which can be readily reset by thermal zeroing, providing the mineralogy is suitable.
5) Perhaps the most important step of all is to articulate the archaeological question and discuss it with the laboratory prior to initiating work. It is important to consider the levels of precision and accuracy which are realistically attainable from individual samples, or groups of samples, and to work out how best to address the most important underlying questions.
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