  Nebular spectra of Supernovae (SNe) offer an unimpeded view of the inner
region of the ejecta, where most nucleosynthesis takes place. Optical spectra
cover most, but not all of the emitting elements, and therefore offer only a
partial view of the products of the explosion. Simultaneous optical-infrared
spectra, on the other hand, contain emission lines of all important elements,
from C and O through to the Intermediate Mass Elements (IME) Mg, Si, S, Ca, and
to Fe and Ni. In particular, Si and S are best seen in the IR. The availability
of IR data makes it possible to explore in greater detail the results of the
explosion. SN\,2007gr is the first Type Ic SN for which such data are
available. Modelling the spectra with a NLTE code reveals that the inner ejecta
contain $\sim 1 \Msun$ of material within a velocity of $\approx 4500$\,\kms.
%The spectrum is powered by \Nifs, in an amount ($0.076 \Msun$) consistent with
that %derived from the early-time data. The same mass of \Nifs\ derived from
the light curve peak ($0.076 \Msun$) was used to power the spectrum, yielding
consistent results. Oxygen is the dominant element, contributing $\sim 0.8
\Msun$. The C/O ratio is $< 0.2$. IME account for $\sim 0.1 \Msun$. This
confirms that SN\,2007gr was the explosion of a low-mass CO core, probably the
result of a star of main-sequence mass $\approx 15 \Msun$. The ratios of the
\CaII\ lines, and of those of \FeII, are sensitive to the assumed degree of
clumping. In particular, the optical lines of [\FeII] become stronger, relative
to the IR lines, for higher degrees of clumping.
