The proportion of amorphous silica is a major determinant of polish development on stone tools used to process plants. Amorphous silica occurs in significant amounts both in plants and in certain types of stone used to make lithic artefacts. Four stages of polish formation are derived from the glass polishing theory because they are useful for identifying mechanisms of how silica acts as a polishing agent. Amorphous silica is found to be an important polishing agent, even for wood with a very low silica content. Polishing agents may also contribute to polishes arising from stone tool contact with bone, skin, meat and shell. Implications are considered for flint, obsidian, quartz and other stone tool materials with use-polish. It is concluded that use-polish may be a less precise indicator of Australian contact materials than has been reported for other areas. © 1991.
