Interstellar polarization and grain alignment: the role of iron and
  silicon
  We compiled the polarimetric data for a sample of lines of sight with known
abundances of Mg, Si, and Fe. We correlated the degree of interstellar
polarization $P$ and polarization efficiency (the ratio of $P$ to the colour
excess $E(B-V)$ or extinction $A_V$) with dust phase abundances. We detect an
anticorrelation between $P$ and the dust phase abundance of iron in non
silicate - containing grains $< [\rm Fe(rest)/H > ]_\rm d$, a correlation
between $P$ and the abundance of Si, and no correlation between $P/E(B-V)$ or
$P/A_V$ and dust phase abundances. These findings can be explained if mainly
the silicate grains aligned by the radiative mechanism are responsible for the
observed interstellar linear polarization.
