Yup, there was (and still is?) a Grindstone City, Michigan. Just as the word "grindstone" is used in a number of old-time sayings such as "Keep Your Nose to the Grindstone". Here are a bunch of these grindstones as they looked about 100 years ago. Perhaps the addages thru the year referring to grindstones came from this locale. Also see the next photo. You can betcha it took a lot of "keeping your nose to the grindstone" to move and haul these mammoth pieces of material around a century ago. Albeit without any hydraulic and little motorized equipment. Whew!!!