Microscopic investigations of the quartz etching technique for TL dating

Experimental conditions for etching quartz inclusions in pottery, for TL dating, in order to reduce their external alpha dose, have been evaluated earlier by weight-loss experiments of bulk amounts of grains. Microscopic studies of the effect of hydrofluoric acid on individual grains revealed that etching depends upon grain morphology. This paper describes the anisotropic etching behaviour of quartz grains in a more quantitative way. The etching time required to reduce the alpha dose to an insignificant amount is evaluated on the basis of microscopic measurements of individual grains. Averaging the dimensions of a great number of these grains after etching confirms the currently used conditions of acid treatment. The residual alpha doses, recovered after etching, do not always correspond to earlier calculations, but indicate that their value is determined by provenance, type and the anisotropy of etching. (author)