About Crystal Grove Diamond Mine and Campground The site has been here about 40 years. It’s a beautiful campground. It’s only 35 sites, so it’s small, but it’s got a lot of trees, wildflowers, birds and peaceful nature to enjoy. We also has the Diamond Mine. There are actually three collecting areas. There are two open pit mines, so nothing is underground. The biggest one is about the size of a football field. We are located about 45 minutes from Cooperstown or Howe Caverns. There are a lot of Revolutionary War sites nearby.