Solid-Phase C-60 in the Peculiar Binary Xx Oph?

We present infrared spectra of the binary XX Oph obtained with the Infrared Spectrograph on the Spitzer Space Telescope. The data show some evidence for the presence of solid C-60 - the first detection of C-60 in the solid phase - together with the well-known 'unidentified infrared' emission features. We suggest that, in the case of XX Oph, the C-60 is located close to the hot component, and that in general it is preferentially excited by stars having effective temperatures in the range 15 000-30 000 K. C-60 may be common in circumstellar environments, but unnoticed in the absence of a suitable exciting source.