Since prehistoric times, the process of cutting rock to make millstones has been one of the most important industries in the world. The earliest rotary millstones, known as querns, were turned by human power. Later, larger millstones were manufactured that required animal, water, or wind power to turn them. These larger millstones required less human effort and ground greater quantities of grain, but also required regular maintenance and replacement. As a result, millstone quarries increased greatly in number and size in the late 19th and early 20th centuries, with the largest quarry sites extending as far as nearly a half-mile square to about 12 square miles. The first part of this book compiles information on the millstone industry in the United States, which dates between the mid-1600s and the mid-1900s. Primarily based on archival research and brief accounts published in geological and historical volumes, it focuses on conglomerate, granite, flint, quartzite, gneiss, and sandstone quarries in different regions and states. The second part focuses on the millstone quarrying industry in Europe and other areas. Of the European millstone industry, the quarries of France, Germany, and Great Britain are most extensively documented, although the quarries of Albania, Austria, the Czech Republic, Greece, Hungary, Italy, Luxembourg, Norway, Slovenia, Spain, Sweden, and Switzerland are also covered. The extensive bibliography provides scholars with many sources for future research. The book includes 84 photographs, 16 tables, and a helpful glossary of specialized and technical terms.