The top part of the grinding stone pair also has a number of names: manos, pestles, handstones, grinding stones, grinders, mobangs. They are also variable in shape, but typically have at least one convex face on the grinding surface that makes contact with the querns.
Manos can be simply round to spherical stones, or long tubes like rolling pins, or shaped like their namesakes, the "grinder" sandwich you pick up at your local deli. The size and shape depends on how the pestle is used: whether the short or broad sides are used for the grinding, the quantity of flour that needs to be produced and/or the kind of grinding required to bring the substance to its preferred floury state.
Grindstone pairs are typically made of coarse, durable stone such as sandstone, granite, dolerite, quartzite, flint, basalt, and even volcanic tuff. Archaeologists have found evidence for grinding millets, wheat, barley, rice, water lily, cattail tubers, maize, quinoa, and animal bone: in fact, almost all edible seeds and grains have been identified archaeologically in association with grinding pairs.
Sources
A bibliography has been built for this project.
