GEOCHEMICAL AND PETROGRAPHIC CHARACTERIZATION OF CHERT WORKABILITY

Ten chert types varying in provenance were fashioned into a basic triangular point and their ease of workability was examined. Petrographic, inductively coupled plasma mass spectrometer laser ablation (ICP-MS-LA), and X-ray diffraction (XRD) analyses were performed on chert. During point manufacturing the properties of each flake removed from chert were recorded. Some of the flaking properties observed were platform angle, flake length, and flake mass. After comparing the flaking properties of chert with the data obtained from the various petrographic and geochemical analyses it appears that chert types characterized by an ordered quartz matrix and that are geochemically pure had the most desirable flaking properties. As examples, Arkansas Novaculite was geochemically pure, had an ordered matrix, homogenous texture, and produced longer flake terminations in the early stages of point manufacturing. Contrarily the impure Tecovas chert, which had a disordered quartz matrix with many chalcedonic regions, created many surficial fractures when processed. However, having an ordered matrix seems to play the more important role in chert workability. The Alibates chert had variable geochemistry and several quartz grain sizes, yet still produced clean terminations throughout point manufacturing. It was the most workable chert type among the three listed here which appears to be the result of the different quartz grain sizes regularly distributed throughout the chert’s matrix. This suggest that homogenous texture and pure geochemistry are not as influential on chert workability as an ordered matrix. The mechanisms behind these observations are currently being investigated.