Subsequent to work by Boustani on B-12 clusters in free space, a study is made of B-12 clusters embedded in graphitic fragments with use of Hartree-Fock methodology. To gain insight about defect embedding for an extended graphite layer, clusters of varying sizes up to 336 C atoms have been studied. Bonding density maps are presented, and bond lengths and valence angles are tabulated for the smallest and the largest clusters studied. Attention is also given in these large clusters to the way the displacements of C atoms from their "ideal" pure-graphitic positions fall off with distance from the B-12 defect.