4179 Toutatis is a very rocky S type asteroid, no doubt the product of one or more asteroid impacts. Recently China's Chang'e 2 probe has revealed even more details of this asteroid's complicated history.
A 10 square mile claim would be enough for basic mining operations and local support structure. Hypothetical estimated value in 2021 USD $1 trillion. The number of available claims is limited to 1.
Image Credit: NASA / JPL-Caltech