NORWEGIAN MICA-SCHIST MILLSTONES IN WISCONSIN AND IOWA: A RARE TYPE OF IMPORTED MILLSTONE

For more than a millennium, mica schists were a favored material for millstone manufacture in Norway. These schists were fairly easy to quarry as they were relatively soft, and their garnet and staurolite inclusions provided for adequate grinding. At least three pair of schist millstones were exported from Scandinavia to Iowa and Wisconsin in the nineteenth century. Two pair are located at the Vesterheim Norwegian-American Museum in Decorah, Iowa, and one pair is exhibited at Beckman Mill in Beloit, Wisconsin. Two of these three pair are known to have been used to grind grain in North America.

All of these millstones are monolithic and discoidal in shape. They range in size from 48 to 54.5 cm in diameter. This size range is typical of quernstones, that is manually-operated millstones, and some contain inserts suggestive of hand grinding. The pair at Beckman Mill was imported in the 1840s. This pair is accompanied by a partially reconstructed milling frame. One pair at the Vesterheim Museum, imported by Knut Norsvin, probably in the 1850s, is now placed inside the Norsvin Mill, a small sod-roofed Norwegian mill brought to the United States at a later date than the millstones within. The lithology of these stones indicates that the historic records of these stones being imported from Norway are accurate.

Other types of millstones, as well as rough pieces of stone intended for use in manufacturing millstones, were more commonly imported into the United States. These include stone from England, Germany, and France. The French stone, a chert known in the United States as French buhr, was by far the most popular. French buhr is still used to grind grain at the Beckman Mill today, and a number of examples of French buhr are present on the grounds of the Vesterheim Norwegian-American Museum. The French millstone at these sites contains fossil charophytes characteristic of the Paris Basin.