  Compelling evidence for band-type conductivity and even bulk
superconductivity below $T\_{\text{c}}\approx 8$ K has been found in
$^{69,71}$Ga-NMR experiments in crystalline ordered, giant Ga$\_{84}$
cluster-compounds. This material appears to represent the first realization of
a theoretical model proposed by Friedel in 1992 for superconductivity in
ordered arrays of weakly coupled, identical metal nanoparticles.
