  Recent XMM-Newton observations of the high-redshift, lensed, broad absorption
line (BAL) quasi-stellar object APM 08279+5255, one of the most luminous
objects in the universe, allowed the detection of a high column density
absorber ($N_H \approx 10^{23}$ cm$^{-2}$) in the form of a K-shell absorption
edge of significantly ionized iron (Fe XV - XVIII) and corresponding ionized
lower-energy absorption. Our findings confirm a basic prediction of
phenomenological geometry models for the BAL outflow and can constrain the size
of the absorbing region. The Fe/O abundance of the absorbing material is
significantly higher than solar (Fe/O = 2-5), giving interesting constraints on
the gas enrichment history in the early Universe.
