Black and white photograph of the post office in Grindstone City, Michigan. There are several smaller grindstones and pieces of the rock piled on the porch. The city was founded around the grindstone quarries, with its primary industry focused on this finest of abrasive stones. After World War I, carborundum replaced grindstone, destroying the industry of the town and the town itself. The city is also spelled Grind Stone City in some sources.