Novel carbon clusters isolated in the solid phase have been characterized by electron ionization (EI) mass spectrometry. The crystalline material contains the C60 and C70 molecules in a ratio of 37:1. Both of these molecules form singly charged ions that appear at m/z 720 and 840, respectively, and doubly charged ions that appear at m/z 360 and 420, respectively. Only the C60 molecule produces the triply charged species, at m/z 240. C60 undergoes fragmentation by losing successive multiples of C2 through C16. The C70 molecule only loses the fragments C2 and C4. Collisionally activated decomposition of these molecules in the first field-free region did not reveal any more extensive fragmentation than was observed under EI conditions.