The use of electron spin resonance (ESR) for the determination of prehistoric lithic heat treatment

The ratio between the concentration of E' centers and of oxygen vacancies in quartz was used to estimate the heating temperature of ancient lithic tool fragments made of cherts; the latter concentration was estimated from the signal intensity of E' centers after converting diamagnetic oxygen vacancies with two electrons into paramagnetic E' centers. Control experiments of temperature estimation were made by granitic quartz grains heated in a laboratory. The results for some lithic tool fragments were consistent with the one by conventional qualitative assessment using the color changes of the samples. (author)