Models for equilibrium forms of protein crystals were suggested using classical methods, such as Stranski-Kaischew's mean-separation-work method and the Gibbs-Curie-Wulff law. Although absolute bonding energies in protein crystal lattices are unknown, their relative strength was estimated from the type of lattice contacts observed in the protein x-ray structures. Equilibrium forms of ferritin crystals deduced on this basis were compared with experimental observations of Yau and Vekilov. (C) 2012 Elsevier B.V. All rights reserved.