  We report discoveries of 165 new quasar Ca II absorbers from the Sloan
Digital Sky Survey (SDSS) Data Release 7 and 12. Our Ca II rest frame
equivalent width distribution supports the weak and strong subpopulations,
split at ${W}^{\lambda3934}_{0}=0.7${\AA}. Comparison of both populations' dust
depletion shows clear consistency for weak absorber association with halo-type
gas in the Milky Way (MW) while strong absorbers have environments consistent
with halo and disc-type gas. We probed our high redshift Ca II absorbers for
2175{\AA} dust bumps, discovering 12 2175{\AA} dust absorbers (2DAs). This
clearly shows that some Ca II absorbers follow the Large Magellanic Cloud (LMC)
extinction law rather than the Small Magellanic Cloud extinction law. About 33%
of our strong Ca II absorbers exhibit the 2175{\AA} dust bump while only 6% of
weak Ca II absorbers show this bump. 2DA detection further supports the theory
that strong Ca II absorbers are associated with disk components and are dustier
than the weak population. Comparing average Ca II absorber dust depletion
patterns to that of Damped Ly{\alpha} Absorbers (DLAs), Mg II absorbers, and
2DAs shows that Ca II absorbers generally have environments with more dust than
DLAs and Mg II absorbers, but less dust than 2DAs. Comparing 2175{\AA} dust
bump strengths from different samples and also the MW and LMC, the bump
strength appears to grow stronger as the redshift decreases, indicating dust
growth and the global chemical enrichment of galaxies in the universe over
time.

Astrophysics of Galaxies;Instrumentation and Methods for Astrophysics