The warm absorber observed in the Seyfert 1 galaxy MCG–6-30-15 is known to consist of at least two zones and very likely contains dust . Hubble Space Telescope images of MCG–6-30-15 show a dust lane crossing the galaxy just below the nucleus .
In this paper , we argue that this dust lane is responsible for the observed reddening of the nuclear emission and the Fe i edge hinted at in the Chandra spectrum of MCG–6-30-15 .
We further suggest that the gas within the dust lane can comprise much of the low ionization component ( i.e. , the one contributing the O vii edge ) of the observed warm absorber .
Moreover , placing the warm absorbing material at such distances ( hundreds of pc ) can account for the small outflow velocities of the low ionization absorption lines as well as the constancy of the O vii edge .
Photoionization models of a dusty interstellar gas cloud ( with a column appropriate for the reddening toward MCG–6-30-15 ) using a toy Seyfert 1 spectral energy distribution show that it is possible to obtain a significant O vii edge ( \tau \sim 0.2 ) if the material is \sim 150 pc from the ionizing source .
For MCG–6-30-15 , such a distance is consistent with the observed dust lane .
We emphasize the point first made by Kraemer et al .
: dusty interstellar material will likely contribute to the warm absorber , and should be included in spectral modeling .

The current data on MCG–6-30-15 is unable to constrain the dust composition within the warm absorber .
Astronomical silicate is a viable candidate , but there are indications of a very low O abundance in the dust , which is inconsistent with a silicate origin .
If true , this may indicate that there were repeated cycles of grain destruction and growth from shocks in the interstellar medium of MCG–6-30-15 .
Pure iron grains are an unlikely dust constituent due to the limit on their abundance in the Galaxy , yet they can not be ruled out .
The high column densities inferred from the highly ionized zone of the warm absorber implies that this gas is dust-free .