HI Nice Crock it is what is called Salt Glazed Stoneware. During the firing of the crock once the kiln had reached the correct temperature the potter would shovel rock salt into the kiln. The high temperature about 2300 degrees F. was enough to vaporize the salt into a highly reactive gas, which would react with the clay creating a very shiny and hard glaze. I would say your crock was made in the Midwest around the 1870s
Thanks for the input everyone. It is a cool piece. It is the only crock type we have found amongst all the bottles,although we have found many remnants in a million pieces.
Regards, Ed