I dug up an insulator from an old privy pit in Wisconsin. It's 3" tall, no embossing, and it's a very dark olive green (almost black). It appears to have a smooth base. There is also a large crescent-shaped chip out of the base. It has a thin seam circling the top, about 1/4" down from the top. And there are vertical seams on each side, running from the upper circular seam down to the bottom. Can you give me an idea of its age, place of manufacture, or value?