A large, heavy disc of hard stone—granite or basalt—turned and fitted into a mill’s turning shaft. The upper stone rotates against a fixed lower stone; grain fed between them is ground to meal or flour. A good millstone is dressed with furrows carved by a specialist stoneworker and may last for decades; worn stones are replaced at great cost by the miller or mill owner.
Millstone
Large granite or basalt disc with dressed furrows; grinds grain for decades.