Phobos is one of the two tiny moons orbiting Mars, so close in fact that astrophysicists estimate that it will crash into Mars in about 20 million years. Phobos is only a few miles wide, so small it has a somewhat irregular shape. The composition of Phobos appears to be that of porous carbonaceous chondrite content, similar to the surface of Mars.
A 10 square mile claim would be enough for basic mining operations and local support structure. Hypothetical estimated value in 2022 USD $10 trillion. This is a limited release asteroid with the number of available claims limited to only 1.
Image Credit: NASA / JPL-Caltech