“…The thicker pieces do not heat or cool evenly and, as a result, crack or craze rather easily'' (Crabtree and Butler, 1964, p. 2). Many experimental programs have sought to define the optimum temperature and length of time required to heat treat siliceous rocks, and observed that these varied between different materials, but these conclusions have not quantified how heating must be varied with specimen size if thermal fracture is to be avoided (Mandeville, 1973;Rick and Chappell, 1983;Bleed and Meier, 1980;Purdy, 1974;Schindler et al, 1982). We tested the effects that altering size had on the temperature at which a raw material fractured.…”