More Georgia granite being tumbled

Yes cobblestone. Granite is very common in central to north Georgia. Many quarries have rail access. Specialized rail cars have gravel spreaders that replenish gravel along rail tracks. The rock is broken up to tumble sized chunks. There are many textures and colors of granite. Different railways may have been covered with granite from a variety of quarries.
Florida is starting to prevent quarrying rock because it damages their low water table and have started importing Georgia granite gravel.

Typical(old) Georgia quarry converted to a granite sand quarry. They let the old quarry fill with water that is used as a closed loop water source for water screening sharp sand to various grit sizes mostly for concrete production. This is a large one.

Stone mountain on horizon. Must be 30 quarries like this within 20 miles of my home in Atlanta. Drone view




adjacent to above quarry, natural granite exposure