Identifying expedient glass tools from a post-contact Tsimshian village using low power (10–100×) magnification

Glass shards from post-contact contexts at the Northern Tsimshian site of Ginakangeek, on the north coast of British Columbia Canada, are identifiable as expedient tool artifacts through analysis of usewear patterns. In this study, we have examined the nature of glass and argued that its mineralogical properties make it analogous to other lithic materials. Although other researchers have found evidence of a lithic-like industry of glass artifacts based on macroscopic features, we have demonstrated that expedient artifacts are identifiable even in the absence of macroscopic traits, through low-power magnification of usewear. We have also tested this thesis against the possibility that microscopic usewear-like patterns were the product of fragmentation or post-depositional effects, and argued that a suite of usewear traits correlates only with use activity. Our experimental suite of glass artifacts indicates that specific actions (such as cutting, scraping, sawing, and chiseling) and the relative hardness of specific substrates produce particular usewear patterns. A number of potential explanations are considered for the appearance of such an industry on the Northwest Coast more than a century after contact with Europeans.