Amorphous carbon has been produced by laser irradiation of single‐crystal and polycrystalline fullerite, via cage opening reactions and coalescence of C60 units. A photothermal oxidation reaction is responsible for fullerene cage opening, and oxygen is also bounded to the final products of the coalescence process. Under inert atmosphere C60 clusters retain their structure even under very high laser fluence. The structure of the new carbon phase has been characterized by Raman scattering and energy‐dispersive x‐ray spectroscopy. A disordered amorphous carbon phase is observed. The evolution of Raman spectra gives information on the kinetics of coalescence and rearrangement of fullerene fragments. © 1995 American Institute of Physics.