Quartz hydration dating
Thermoluminescence emits a weak light signal that is proportional to the radiation dose absorbed by the material. The technique has wide application, and is relatively cheap at some US0–700 per object; ideally a number of samples are tested. The destruction of a relatively significant amount of sample material is necessary, which can be a limitation in the case of artworks.
Optically stimulated luminescence dating is a related measurement method which replaces heating with exposure to intense light.
The sample material is illuminated with a very bright source of green or blue light (for quartz) or infrared light (for potassium feldspars).
Ideally this is assessed by measurements made at the precise findspot over a long period.
For artworks, it may be sufficient to confirm whether a piece is broadly ancient or modern (that is, authentic or a fake), and this may be possible even if a precise date cannot be estimated.
Different materials vary considerably in their suitability for the technique, depending on several factors.
Subsequent irradiation, for example if an x-ray is taken, can affect accuracy, as will the "annual dose" of radiation a buried object has received from the surrounding soil.
Thermoluminescence dating is used for material where radiocarbon dating is not available, like sediments.
Its use is now common in the authentication of old ceramic wares, for which it gives the approximate date of the last firing.
Natural crystalline materials contain imperfections: impurity ions, stress dislocations, and other phenomena that disturb the regularity of the electric field that holds the atoms in the crystalline lattice together.