Heat treatment of silicate toolstone was performed prehistorically, which we assume was to improve characteristics desired in flintknapping, such as increased brittleness and more predictable and controlled conchoidal fracture. However, despite research into heat treatment spanning 50 years, the mechanisms by which stone was improved, and the reasons why people did it, remain unclear. In this study, experiments were designed to test two potential outcomes of heat treatment for Pennsylvania jasper. First, does heating reduce the disruptive effect of macroscopic impurities and flaws on controlled flaking? Second, does heating increase the stone’s brittleness as suggested by Crabtree and Butler in 1964? Such physical alterations would improve the quality of lithic material but may not always occur in high quality stone. The results of these experiments are used to hypothesize the expected heat treatment outcomes sought after by prehistoric flintknappers.

中文翻译：

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宾夕法尼亚碧玉的热处理

硅酸盐工具石的热处理是在史前进行的，我们假设这是为了改善打火石所需的特性，例如增加脆性和更可预测和控制的贝壳状断裂。然而，尽管对热处理进行了 50 年的研究，但改善石材的机制以及人们这样做的原因仍不清楚。在这项研究中，实验旨在测试宾夕法尼亚碧玉热处理的两种潜在结果。首先，加热是否会减少宏观杂质和缺陷对受控剥落的破坏性影响？其次，加热是否会像 Crabtree 和 Butler 在 1964 年提出的那样增加宝石的脆性？这种物理改变会提高石料的质量，但可能并不总是发生在高质量的石头中。