The thermoluminescence (TL) of several Pacific N.W. Obsidian sources has been studied in order to find out to what extent it can be used to characterize these sources and hence identify the sources of artifacts. Both the natural TL and TL resulting from a laboratory radiation dose are reported. It is found that the different sources do exhibit characteristically different TL glow curve shapes and that these have a within-source intensity variation typically of a factor of three; the between source variation is over four orders of magnitude The method was tested by measuring the TL of several artifacts. It is concluded that thermoluminescence can be used as a method of characterization.