  The analysis of Perseus data collected with the Medium Energy Concentrator
Spectrometer (MECS) on board Beppo-SAX shows that the ratio of the flux of the
8 keV line complex (dominated by Fe K$_{\beta}$ emission) over the 6.8 keV line
complex (dominated by Fe K$_{\alpha}$ emission) is significantly larger than
predicted by standard thermal emission codes. Moreover the analysis of
spatially resolved spectra shows that the above ratio decreases with increasing
cluster radius. We find that, amongst the various explanations we consider, the
most likely requires the plasma to be optically thick for resonant scattering
at the energy of the Fe K$_{\alpha}$ line. We argue that if this is the case,
then measures of the iron abundance made using standard thermal emission codes,
that assume optically thin emission, can significantly underestimate the true
iron abundance. In the case of the core of Perseus we estimate the true
abundance to be $\sim$ 0.9 solar in a circular region with radius of $\sim 60$
kpc and centered on NGC 1275. Finally we speculate that similar results may
hold for the core of other rich clusters.
