C-type asteroid
The largest unequivocally C-type asteroid is 10 Hygiea, although the SMASS classification places the largest asteroid, 1 Ceres, here as well, because that scheme lacks a G-type.
10 Hygiea
Hygiea (minor planet designation: 10 Hygiea) is the fourth-largest asteroid in the Solar System by volume and mass, and it is located in the asteroid belt. With somewhat oblong diameters of and a mass estimated to be 2.9% of the total mass of the belt, it is the largest of the class of dark C-type asteroids with a carbonaceous surface.