The band structures of C 3 and C 6 are different, although they are similar in shape. The lowest CB band is at M in both. For the VB, however, the highest band is found at A point in C 3 , whereas in C 6 the highest valence band is at the  point, as is more commonly found. In C 9 the band gap is small ~0.5 eV, indicating semiconducting behavior. Finally, the largest band gap is observed for the diamond-like C 12 with a magnitude close to 4 eV with indirect  VB -M CB character. [34] 4.1186 [34] 3.5164 97 443 Diamond Fd-3m 3.56661 [35] 3.5169 98 445 [26] Table Mechanical properties of hexagonal carbon allotropes: Vickers hardness (H V ), bulk modulus (B), shear modulus (G), Young's modulus (E), Poisson's ratio () and fracture toughness (K Ic ) [26] 530 [26] 1138 0.074 6.4