(120216) 2004 EW95 is a large C type asteroid of carbonaceous content. In addition, certain compounds related to planetary formation have been detected on its surface, making its origin an intriguing puzzle, and leaving open the possibility of a higher rare earth element content. One of the drawbacks to this asteroid is its remote location in the Kuiper belt.
A 10 square mile claim would be enough for basic mining operations and local support structure. Hypothetical estimated value in 2017 USD $1 trillion. The number of available claims is limited to 26,603.
Image Credit: NASA / JPL-Caltech