The term tool stone has multiple meanings. In archaeology, a tool stone is a type of stone that is used to manufacture stone tools. Alternatively, the term can be used to refer to stones used as the raw material for tools.
Generally speaking, tools that require a sharp edge are made using cryptocrystalline materials that fracture in an easily controlled conchoidal manner. Cryptocrystalline tool stones include flint and chert, which are fine-grained sedimentary materials; rhyolite and felsite, which are igneous flowstones; and obsidian, a form of natural glass created by igneous processes. These materials fracture in a predictable fashion, and are easily resharpened. For more information on this subject, see lithic reduction.
Large-grained materials, such as basalt, granite, and sandstone, may also be used as tool stones, but for a very different purpose: they are ideal for ground stone artifacts. Whereas cryptocrystalline materials are most useful for killing and processing animals, large-grained materials are usually used for processing plant matter. Their rough faces often make excellent surfaces for grinding plant seeds. With much effort, some large-grained stones may be ground down into awls, adzes, and axes.
In metal-working fragments of diamond are bonded to the edge of cutting tools.
- Andrefsky Jr., William (2005). Lithics: Macroscopic Approaches to Analysis (Second Edition ed.). Cambridge University Press. ISBN 0-521-61500-3.
- Daniel S. Amick (1999). Folsom lithic technology: explorations in structure and variation. International Monographs in Prehistory. ISBN 978-1-879621-27-5. Retrieved 2010-10-03.
- David E. Koskoff (1981). The diamond world, Volume 1981, Part 2. Harper & Row. ISBN 978-0-06-038005-2. Retrieved 2010-10-03. "This second diamond, known as the tool stone, is cemented to a short pole, ... As the revolving stone repeatedly knocks against the tool stone, the out-of-circular portions of the stone being worked are knocked off"
- Mining journal, Volume 259. p. 167. Retrieved 2010-10-03. "Diamond substitutes for Green Grit. More suitable bonds substitute for less suitable bonds. Diamond bonded products substitute for non-diamond products. Specialised tool-stone selection substitutes for inexperienced diamond selection. ..."