This is a block of salt. It is in South Hutchinson, Kansas, on the spot where salt was first discovered in this area on September 27, 1887. The man who discovered it, Ben Blanchard, was actually looking for oil.
Salt was a pretty important discovery, though. When the new processing plant produced its first barrel of salt a year later, 5,000 people turned out for the occasion. Even today, salt production continues to be a key part of the local economy.
Unfortunately, Ben Blanchard didn’t share in the resulting prosperity. He was too busy escaping from failed real estate deals.
The Kansas Underground Salt Museum is not far from this block of salt. You can take a tour, but they recommend reservations.