Sidonia is a mysterious and rare T type asteroid with a dark and unknown composition. Speculation has it that it could possibly be due to unique rare earth element minerals. It is a small asteroid so only 1140 claims are available.
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 800.
Image Credit: NASA / JPL-Caltech