Crystals grown by evaporating C-60 solutions in n-nonane were found to be crystals of the C-60 (.) 2/3 n-nonane solvate, after they were stored for eight years in the dark at room temperature. The lattice is an I-centered orthorhombic lattice (a = 10.10(1) Angstrom, b = 10.19(1) Angstrom, c = 48.71(5) Angstrom), that forms with a negative excess volume of about -3.1%, and loses its solvent from about 399 K with an enthalpy change of about 49 J per gram of solvate. Thermodynamic and crystallographic data for available C-60-n-alcane solvates are discussed and a van der Waals volume of 603 Angstrom(3) per C60 isolated molecule is proposed. (C) 2004 Elsevier B.V. All rights reserved.