CaII Absorbers in the Sloan Digital Sky Survey: Element Abundances and
  Dust
  We present measurements of element abundance ratios and dust in
CaII~absorbers identified in SDSS DR7+DR9. In an earlier paper we formed a
statistical sample of 435 CaII absorbers and postulated that their statistical
properties might be representative of at least two populations of absorbers.
Here we show that if the absorbers are roughly divided into two subsamples with
CaII rest equivalent widths larger and smaller than $W_0^{\lambda 3934} = 0.7$
\AA, they are then representative of two physically different populations.
Comparisons of abundance ratios between the two CaII absorber populations
indicate that the weaker $W_0^{\lambda 3934}$ absorbers have properties
consistent with halo-type gas, while the stronger absorbers have properties
intermediate between halo- and disk-type gas. We also show that, on average,
the dust extinction properties of the overall sample is consistent with a LMC
or SMC dust law, and the stronger absorbers are nearly 6 times more reddened
than their weaker counterparts. The absorbed-to-unabsorbed composite flux ratio
at $\lambda_{rest} = 2200$ \AA\ is $\mathcal{R} \approx 0.73$ and $E(B-V)
\approx 0.046$ for the stronger CaII absorbers ($W_0^{\lambda 3934} \ge 0.7$
\AA), and $\mathcal{R} \approx 0.95$ and $E(B-V) \approx 0.011$ for the weaker
CaII absorbers ($W_0^{\lambda 3934} < 0.7$ \AA).
