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Understanding the Effects of Heat Treatment on Edwards Plateau Chert

Abstract Heat treatment or thermal alteration was a technology that prehistoric and historic knappers used to change the mechanical properties of various siliceous minerals. This technology allowed them to create quality materials for stone tool production out of otherwise substandard raw materials. The heat treatment of siliceous minerals to improve flaking qualities in prehistory was a near global phenomenon (Domanski and Webb 1992). In North America, the time span of this technology ranged from Paleo-Indian contexts to historic accounts. Although there is ample proof of heat treating in the archaeological record through the inspection of color and luster change of artifacts, the exact mechanism of heat treatment used eludes archaeologists today. This paper presents an experimental study of heat treating Edwards Plateau chert to evaluate changes in the hardness value and fracture toughness of this North American lithic material.