Compare physical properties of diamond and graphite to those Buckminsterfullerene.?

diamonds are the hardest material due to the configuation of the C atoms in a diamond.  the bonds are huge covalent bonds between each C atom creating a single molecule of C, a network solid

in graphite, the C atoms are sp2 carbons and the covalent bonds are much weaker than in the diamond.  the bond lengths are longer bewteen the C atoms making the bonds more easy to break.  less energy is required so the C atoms just "slough" off when a pencil comes into  contact with paper

in a fullerene, the C atoms are connected to other carbon atoms with 2 single bonds and a double bond.  the double bonds give the fullerene the strength but, as it is not a network solid like a diamond, it lacks the bond strength of a diamond