  Companion stars exposed to high energy radiation from a primary neutron star
or accreting black hole can experience significant spallation of their heavy
elements, so that their atmospheres would be extremely rich in lithium,
beryllium, and especially boron. In this paper we note that the detection or
non-detection of these elements, and their relative abundances if detected,
would provide a diagnostic of the high energy output of the primary, and
possibly the shock acceleration of particles at the companion's bow shock in a
pulsar wind.
