Crystals of ${\mathrm{C}}_{60}$ or ${\mathrm{C}}_{70}$ cocrystallized with n-pentane grow as elongated, ten-sided columns. X-ray diffraction shows ordering of ${\mathrm{C}}_{60}$ or ${\mathrm{C}}_{70}$ molecules along the column and a remarkable tenfold symmetry normal to the column. The ratio of the x-ray-diffraction vectors of the two lowest-order diffraction spots is nearly equal to the ‘‘golden ratio,’’ τ. Despite these similarities with decagonal, quasicrystalline order, the diffraction indicates crystalline order with a twinned unit cell.

• Received 18 March 1991

DOI:https://doi.org/10.1103/PhysRevB.44.888