Prehistoric obsidian quarries in the western Great Basin show peak levels of use ca. 3150-1350 B.P. immediately followed by sharp declines in overall volume and a shift away from biface production. The models developed to explain this pattern either view quarry use as part of a trans-Sierra Nevada luxury exchange network with central and southern California populations as primary consumers, or as utilitarian toolstone procurement responding to western Great Basin settlement patterns and mobility. Obsidian hydration dates obtained on artifacts systematically collected from the Truman/Queen source demonstrates a history of use similar to other sources, suggesting that regional changes in western Great Basin obsidian quarry use was not the result of trans-Sierra Nevada exchange because Truman/Queen obsidian is virtually absent west of the Sierra Nevada. The results of this study also indicate that models that emphasize mobility as the primary conditioner of lithic technology are also inadequate. First order determinants of technology are most likely subsistence related and based on the ability of a specific tool form to contribute to subsistence return rates by reducing resource handling time. Differential mobility likely contributes to technology in a lesser way, affecting decisions regarding degrees of processing, such as biface stage, primary and secondary reduction loci, but not ultimately tool form.